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Review
Metabolite-mediated mechanisms linking the urinary microbiome to bladder cancer
Thu Anh Trần, Ho Young Lee, Hae Woong Choi
J. Microbiol. 2025;63(11):e2509001.   Published online November 30, 2025
DOI: https://doi.org/10.71150/jm.2509001
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AbstractAbstract PDF

Bladder cancer is the most common malignancy of the urinary tract and is a major health burden globally. Recent advances in microbiome research have revealed that the urinary tract harbors a resident microbial community, overturning the long-held belief in its sterility. Increasing evidence suggests that microbial dysbiosis and microbially derived metabolites contribute to bladder cancer carcinogenesis, progression, and therapeutic responses. Distinct microbial signatures have been observed in bladder cancer patients, with notable differences across disease stages and between primary and recurrent cases. Mechanistic studies have demonstrated that microbe-associated metabolites and toxins can drive DNA damage, chronic inflammation, extracellular matrix remodeling, and epithelial–mesenchymal transition. In addition, biofilm formation allows bacteria to evade immune responses and promotes persistent inflammation, creating a tumor-permissive niche. Beyond pathogenesis, microbial activity also influences therapeutic outcomes; for instance, some microbial pathways can inactivate frontline chemotherapy, while others generate metabolites with anti-tumor properties. Collectively, these patterns define a microbiota–metabolite–immunity axis, presenting opportunities for precision oncology. Targeting microbial pathways, profiling urinary microbiota, and harnessing beneficial metabolites offer promising advancements in biomarker discovery, prognostic refinement, and the development of novel therapeutic strategies for bladder cancer.

Full articles
Lactiplantibacillus koreensis sp. nov. and Lactiplantibacillus kimchii sp. nov., isolated from kimchi, a traditional Korean fermented food
Min Ji Lee, Jisu Lee, Sohee Nam, Mi-Ja Jung, Yeon Bee Kim, Yujin Kim, Jeong Ui Yun, Seong Woon Roh, Tae Woong Whon, Che Ok Jeon, Se Hee Lee
J. Microbiol. 2025;63(11):e2507007.   Published online November 30, 2025
DOI: https://doi.org/10.71150/jm.2507007
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AbstractAbstract PDFSupplementary Material

Two Gram-stain-positive, facultatively anaerobic, rod-shaped, and non-motile lactic acid bacterial strains, designated as strains CBA3605T and CBA3606T, were isolated from kimchi, a traditional Korean fermented food. Both strains were oxidase- and catalase-negative, non-spore-forming, non-hemolytic, and non-gas-producing. Optimal growth conditions for the two strains were observed at 30°C, pH 5.0, and 0% NaCl. The two genomes were composed of a circular chromosome and three plasmids and the DNA G + C content of 43.0%, respectively. Strains CBA3605T and CBA3606T were most closely related to Lactiplantibacillus (Lp.) pingfangensis 382-1T with 16S rRNA sequence similarity of 99.4% and 99.1%, respectively. However, the orthologous average nucleotide identities between CBA3605T and CBA3606T were 91.7%, and those with strain 382-1T were 76.9% and 76.5%, respectively. Digital DNA–DNA hybridization values between CBA3605T and CBA3606T were 45.0%, and those with strain 382-1T were 21.4% and 21.0%, respectively. The major fatty acids detected in both strains included C16:0, C18:1 ω9c, and summed features 7 (C19:1 ω7c, C19:1 ω6c, C19:0 cyclo ω10c, and/or C19:0 ω6c). The peptidoglycan of both strains CBA3605T and CBA3606T contained meso-diaminopimelic acid and was classified as A4α type (L-Lys–D-Asp). In polar lipid analyses, only strain CBA3605T contained aminophosphoglycolipid, which was absent in CBA3606T, although both strains harbored same major polar lipids (diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine). Based on phenotypic, phylogenetic, genomic, biochemical, and chemotaxonomic analyses, strains CBA3605T and CBA3606T represent two novel species of the genus Lactiplantibacillus, for which the names Lactiplantibacillus koreensis sp. nov. and Lactiplantibacillus kimchii sp. nov. are proposed, with CBA3605T (= KACC 81073BPT = JCM 37965T), and CBA3606T (= KACC 81074BPT = JCM 37966T) as the type strains.

Inhibition of cardiolipin biosynthesis partially suppresses the sensitivity of an Escherichia coli mutant lacking OmpC to envelope stress
Dae-Beom Ryu, Umji Choi, Gyubin Han, Chang-Ro Lee
J. Microbiol. 2025;63(11):e2507004.   Published online November 30, 2025
DOI: https://doi.org/10.71150/jm.2507004
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AbstractAbstract PDFSupplementary Material

Porins in the outer membrane (OM) of Gram-negative bacteria play two main functions: passage of various extracellular molecules and maintenance of membrane integrity. OmpC, a non-specific porin, is involved in both functions; however, the exact mechanism of maintenance of membrane integrity remains unknown. In this study, we found that inhibiting cardiolipin biosynthesis partially restored the growth defect of the ompC mutant under envelope stress. Among the three enzymes involved in cardiolipin biosynthesis, ClsABC, this effect is primarily associated with ClsA. Notably, the deletion of ClsA also suppressed the similar phenotypes of an Escherichia coli mutant lacking YhdP, a transmembrane protein involved in phospholipid transport from the inner membrane to the OM. Collectively, these results imply that OmpC may contribute to membrane integrity, partially through mechanisms linked to transport or biosynthesis of phospholipids such as cardiolipin.

Development of an RT-LAMP−CRISPR/Cas12a assay for rapid and specific detection of Bandavirus dabieense
Bo Seung Song, Yun Hee Baek, Eun-Ha Kim, Hyeok-Il Kwon, Ah-Hyeon Kim, Si-Hyun Lee, Yu-Bin Son, Soo-Hyeon Kim, Min-Suk Song, Young Ki Choi, Su-Jin Park
J. Microbiol. 2025;63(11):e2506013.   Published online November 30, 2025
DOI: https://doi.org/10.71150/jm.2506013
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AbstractAbstract PDF

Bandavirus dabieense, a single-stranded RNA virus, is the causative agent of severe fever with thrombocytopenia syndrome (SFTS), a disease associated with high fatality rates. Early and accurate diagnosis is essential for improving clinical outcomes, particularly given the limited therapeutic options and high mortality rates associated with SFTS. However, while highly sensitive, conventional diagnostic methods such as PCR and qRT-PCR require specialized laboratory facilities and trained personnel, making them impractical for rapid detection in resource-limited settings. To address these challenges, we developed a rapid and highly sensitive assay for Bandavirus dabieense detection by integrating reverse transcription loop-mediated isothermal amplification (RT-LAMP) with CRISPR/Cas12a technology. LAMP primers and guide RNA sequences were designed to target the L gene, ensuring broad detection across viral genotypes. The optimized assay demonstrated a detection limit of 5 RNA copies per reaction, showing more sensitivity than qRT-PCR, and exhibited 100% concordance with qRT-PCR results in clinical samples. Given its speed, accuracy, and field applicability, this LAMP-CRISPR/Cas12a-based assay represents a promising diagnostic tool for early SFTSV detection, particularly in resource-constrained environments where conventional molecular diagnostics are not readily available.

Encapsulin protein MAV2054 enhances Mycobacterium avium virulence by promoting Cdc42-dependent epithelial cell invasion
Dong Ho Kim, I Jeong Jo, Min Ju Kang, Yi Seol Kim, Duyen Do Tran Huong, Kyungho Woo, Ho-Sung Park, Hwa-Jung Kim, Chul Hee Choi
J. Microbiol. 2025;63(11):e2506008.   Published online November 30, 2025
DOI: https://doi.org/10.71150/jm.2506008
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AbstractAbstract PDF

Mycobacterium avium complex (MAC) organisms are widespread environmental pathogens associated with chronic pulmonary infections. Although M. avium is known to invade epithelial cells, the molecular mechanisms underlying this process remain incompletely understood. In this study, we identified a novel role for MAVRS09815 (formerly MAV2054), a family 2A encapsulin nanocompartment shell protein, in mediating bacterial adhesion, epithelial cell invasion, and in vivo virulence. We engineered a recombinant M. smegmatis strain expressing MAV2054 (Ms_2054) and an M. avium MAV2054 deletion mutant (Δ2054). Ms_2054 exhibited enhanced epithelial invasion, whereas Δ2054 showed reduced intracellular survival. Recombinant MAV2054 protein was bound directly to human epithelial cells in a dose-dependent manner. Pretreatment of host cells with cytochalasin D or vinblastine significantly inhibited bacterial internalization, indicating that MAV2054-mediated invasion is cytoskeleton-dependent. Confocal and scanning electron microscopy revealed MAV2054-dependent membrane rearrangements during infection. Pull-down assays demonstrated that MAV2054 activates Cdc42, a key regulator of actin polymerization, with reduced activation observed in Δ2054-infected cells. In a murine intratracheal infection model, the Δ2054 exhibited significantly reduced bacterial burdens and lung inflammation compared to the wild type. These findings demonstrate that MAV2054 enhances M. avium virulence by promoting epithelial cell invasion through Cdc42-dependent cytoskeletal remodeling. This study reveals a previously unrecognized role for an encapsulin-like protein in host-pathogen interactions and highlights its potential as a therapeutic target in MAC infections.

Safety evaluation and hypolipidemic ability of water-soluble blue pigment extracted by HPD-400 resin from Quambalaria cyanescens
Ruobing Shi, Chengzhong Wang, Nianping Xue, Zhiguo Zhang
J. Microbiol. 2025;63(11):e2412011.   Published online November 30, 2025
DOI: https://doi.org/10.71150/jm.2412011
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AbstractAbstract PDF

The oral administration of synthetic drugs can effectively reduce blood lipid levels, but adverse reactions may occur. Because of this, the hypolipidemic ability of natural products has been increasingly investigated. We evaluate the safety and hypolipidemic characteristics of a water-soluble blue pigment extracted using HPD-400 resin from the fungus Quambalaria cyanescens. Hypolipidemic ability was examined by constructing a hyperlipidemia model with different doses of blue pigment (50, 100, and 200 mg/kg. mouse body weight) for 28 d. Blue pigment purity increased from 20.32% to 70.70% following treatment with HPD-400 resin. Acute toxicity tests revealed blue pigment sourced from Q. cyanescens to have no toxic effects on mouse body weight, mortality, or behavioral characteristics. Subacute toxicity tests revealed no significant differences in food intake, body weight, or organ weights between treatment groups and controls. Histopathological examination of the liver and kidney tissues of mice administered blue pigment were normal, and serum enzyme activities and blood constituents were also within normal ranges. Blue pigment can significantly reduce the weight of mice, reduce liver and kidney damage and fat accumulation. It can also reduce total cholesterol, triglyceride and low density lipoprotein cholesterol in serum and liver tissue, and increase the level of high density lipoprotein cholesterol. Reduce the levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, creatinine, urea and uric acid in serum. Increase the activities of total superoxide dismutase, glutathione peroxidase and catalase in serum and liver tissue, reduce the content of malondialdehyde, and up-regulate liver lipase and lipoprotein lipase. Our work proves that blue pigment is nontoxic, has the function of reducing blood lipid, and can alleviate obesity-related symptoms by regulating lipid metabolism and oxidative stress.

Lactobacillus crispatus KBL693 alleviates atopic dermatitis symptoms through immune modulation
Seokcheon Song, Jun-Hyeong Kim, Sung Jae Jang, Eun Jung Jo, Sang Kyun Lim, GwangPyo Ko
J. Microbiol. 2025;63(10):e2509005.   Published online October 31, 2025
DOI: https://doi.org/10.71150/jm.2509005
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AbstractAbstract PDFSupplementary Material

Atopic dermatitis (AD) is a widespread inflammatory skin condition that affects the population worldwide. Given the implication of microbiota in AD pathogenesis, we investigated whether human-derived Lactobacillus strains could modulate AD. In this study, we identified Lactobacillus crispatus KBL693 as a probiotic candidate for AD treatment. In vitro, KBL693 suppressed mast cell degranulation and IL-4 production by T cells, suggesting its ability to attenuate key type 2 immune responses. Consistent outcomes were observed in a murine AD model, where oral administration of KBL693 alleviated disease symptoms and reduced hallmark type 2 immune markers, including plasma IgE as well as IL-4, IL-5, and IL-13 levels in skin lesions. In addition to downregulating these AD-associated immune responses, KBL693 promoted regulatory T cell (Treg) expansion in mesenteric lymph nodes, indicating its potential to restore immune balance. Collectively, these findings highlight the therapeutic potential of KBL693 for AD through enhancement of Tregs and suppression of type 2 immune responses.

Review
Structural analysis of dual specificity phosphatases, the only type of protein tyrosine phosphatases found in humans and across diverse microorganisms
Bonsu Ku
J. Microbiol. 2025;63(10):e2506006.   Published online October 31, 2025
DOI: https://doi.org/10.71150/jm.2506006
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AbstractAbstract PDFSupplementary Material

Dual specificity phosphatases (DUSPs), a subfamily of the protein tyrosine phosphatase (PTP) family, dephosphorylate not only phosphotyrosine but also phosphoserine and phosphothreonine residues. Beyond the 26 members of this family in humans, DUSPs represent the only type of PTPs found across a wide range of microorganisms, including bacteria, archaea, and viruses. This review presents a comprehensive structural analysis of human and microbial DUSPs. These proteins commonly share core features, such as a typical DUSP fold, shallow active site pocket, signature active site motif known as the P-loop, and conserved aspartate residue that acts as a general acid/base. However, DUSPs from diverse microorganisms also display unique structural and functional characteristics. Pseudomonas aeruginosa TpbA is the only bacterial DUSP identified to date, while a second candidate was proposed in this review. Archaeal DUSPs are hyperthermostable, contain a unique motif in their P-loops, and employ dual general acid/base residues. Poxviral DUSPs are characterized by the formation of domain-swapped homodimers. The presence of DUSPs across all domains of life and viruses, along with their low specificity for phosphorylated amino acids and structural similarity to classical PTPs, suggests that DUSPs represent the ancestral form of PTPs.

Full articles
Mannose phosphotransferase system subunit IID of Streptococcus mutans elicits maturation and activation of dendritic cells
Sungho Jeong, Chaeyeon Park, Dongwook Lee, Hyun Jung Ji, Ho Seong Seo, Cheol-Heui Yun, Jintaek Im, Seung Hyun Han
J. Microbiol. 2025;63(10):e2505014.   Published online October 31, 2025
DOI: https://doi.org/10.71150/jm.2505014
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AbstractAbstract PDF

Streptococcus mutans is a Gram-positive pathogen that causes dental caries and subsequent pulpal infection leading to pulpitis. Although dendritic cells (DCs) are known to be involved in disease progression and immune responses during S. mutans infection, little is known about which component of S. mutans is responsible for the DC responses. Although the mannose phosphotransferase system (Man-PTS) is the primary sugar transporter of S. mutans, it is also a potential virulence factor. Since Man-PTS subunit IID (ManIID) embedded on the bacterial membrane is indispensable for Man-PTS function, we investigated its role in the maturation and activation of DCs stimulated with a ManIID-deficient strain (Δpts) of S. mutans and recombinant ManIID (rManIID) protein. When mouse bone marrow-derived DCs were treated with heat-killed S. mutans wild-type (WT) or Δpts, bacterial adherence and internalization of Δpts were lower than those of WT. Moreover, the heat-killed S. mutans Δpts strain was inferior to the wild-type in inducing expression of phenotypic maturation markers, such as CD80, CD86, MHC-I, and MHC-II, and proinflammatory cytokine, IL-6. In line with the trends in marker expression, the endocytic capacity of DCs treated with the Δpts strain was comparable to that of untreated DCs whereas DCs treated with the WT strain dose-dependently lost their endocytic capacity. Furthermore, rManIID dose-dependently promoted both phenotypic maturation marker expression and IL-6 production by DCs. Collectively, these results demonstrate that ManIID plays a crucial role in the adhesion and internalization of S. mutans into DCs and is one of the major immune-stimulating agents responsible for maturation and activation of DCs during S. mutans infection.

Genome-based classification of Paraniabella aurantiaca gen. nov., sp. nov., isolated from soil and taxonomic reclassification of five species within the genus Niabella
Yong-Seok Kim, Yerang Yang, Miryung Kim, Do-Hoon Lee, Chang-Jun Cha
J. Microbiol. 2025;63(10):e2505005.   Published online October 31, 2025
DOI: https://doi.org/10.71150/jm.2505005
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AbstractAbstract PDFSupplementary Material

A Gram-stain-negative, aerobic, non-motile, rod-shaped, and orange-pigmented bacterium, designated CJ426T, was isolated from ginseng soil in Anseong, Korea. Strain CJ426T grew optimally on Reasoner’s 2A agar at 30°C and pH 7.0 in the absence of NaCl. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain CJ426T belonged to the family Chitinophagaceae and had the highest sequence similarity with Niabella hibiscisoli KACC 18857T (98.7%). The 16S rRNA gene sequence similarities with other members of the genus Niabella ranged from 92.3% to 98.1%. Phylogenomic analyses and overall genomic relatedness indices, including average nucleotide identity, average amino acid identity, and the percentage of conserved proteins values, supported the classification of strain CJ426T as a representative of a novel genus within the family Chitinophagaceae. Furthermore, genome-based analyses suggested that five members of the genus Niabella, including N. aquatica, N. defluvii, N. ginsengisoli, N. hibiscisoli, and, N. yanshanensis, should be separated from other Niabella species and be assigned as a novel genus. The major isoprenoid quinone of strain CJ426T was menaquinone-7 (MK-7). The predominant polar lipids were phosphatidylethanolamine and six unidentified aminolipids. The major fatty acids were iso-C15:0, iso-C15:1 G, and iso-C17:0 3-OH. The genome of strain CJ426T was 6.3 Mbp in size, consisting of three contigs, with a G + C content of 41.9%. Based on a polyphasic taxonomic approach, strain CJ426T represents a novel genus and species within the family Chitinophagaceae, for which the name Paraniabella aurantiaca gen. nov., sp. nov. is proposed. The type strain is CJ426T (= KACC 23908T = JCM 37728T).

Cryo-EM structure of the glycosylated protein CgeA in the crust of Bacillus subtilis endospores
Migak Park, Doyeon Kim, Yeongjin Baek, Eunbyul Jo, Jaekyung Hyun, Nam-Chul Ha
J. Microbiol. 2025;63(10):e2504013.   Published online October 31, 2025
DOI: https://doi.org/10.71150/jm.2504013
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AbstractAbstract PDFSupplementary Material

The Bacillus subtilis spore crust is an exceptionally robust proteinaceous layer that protects spores under extreme environmental conditions. Among its key components, CgeA, a glycosylation-associated protein, plays a critical role in modifying crust properties through its glycosylated moiety, enhancing spore dispersal in aqueous environments. In this study, we present the high-resolution cryo-electron microscopy structure of the core region of CgeA at 3.05 Å resolution, revealing a doughnut-like hexameric assembly. The N-terminal regions are disordered, whereas the C-terminal region forms the core of the hexamer. Although the loop containing Thr112 was not resolved in the density map, its location can be inferred from surrounding residues, suggesting that Thr112 is situated on the exposed surface of the hexamer. On the opposite face, a distinct electrostatic pattern is observed, featuring a negatively charged central pore and a positively charged outer surface. Modeling and biochemical studies with the putative glycosyltransferase CgeB provide insights into how the glycosyl group is transferred to Thr112. This study offers a molecular-level understanding of the assembly, glycosylation, and environmental adaptability of the B. subtilis spore crust, with valuable implications for controlling spore formation in industrial applications.

Bak and Bax are crucial for Gbp2-mediated pyroptosis during Vibrio and Salmonella infections
Yongyang Luo, Jeehyeon Bae
J. Microbiol. 2025;63(9):e2508004.   Published online September 30, 2025
DOI: https://doi.org/10.71150/jm.2508004
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AbstractAbstract PDFSupplementary Material

Pyroptosis a lytic form of programmed cell death, is a crucial host defense mechanism against bacterial pathogens. While caspase-mediated pathways are central to pyroptosis, the involvement of apoptotic regulators such as Bak, Bax, and MCL-1 in bacterial infection-induced pyroptosis remains unclear. Here, we investigated how these BCL-2 family proteins modulate pyroptosis induced by Vibrio vulnificus and Salmonella enterica serovar Typhimurium in murine cells. In mouse embryonic fibroblasts (MEFs), both pathogens strongly induced Gbp2 expression and activated caspase‑11, whereas activation of caspase‑1 occurred only in macrophages, indicating engagement of both non-canonical and canonical pyroptosis pathways. Importantly, Bak-/- and Bax-/- MEFs exhibited significantly reduced Gbp2 upregulation and caspase-11 activation-an effect most pronounced in Bak-deficient cells leading to attenuated pyroptotic cell death. These data suggest that pro-apoptotic proteins, Bak and Bax, act as positive regulators that amplify the Gbp2-caspase-11 axis. Conversely, overexpression of the anti-apoptotic protein MCL‑1 had no significant impact on Gbp2 expression, caspase activation, membrane integrity, or LDH release, indicating that pyroptosis proceeds independently of MCL‑1 regulation. Collectively, our findings uncover a novel role for Bak and Bax in promoting Gbp2-driven pyroptosis during Gram-negative bacterial infections, while MCL‑1 does not impede this process. This work expands our understanding of the crosstalk between apoptotic and pyroptotic pathways in innate immune responses.

Protocol
Protocol for efficient recovery of high-quality DNA from microbiome of marine invertebrates
Yeong-Jun Park, Jae Kyu Lim, Yeon-Ju Lee, Kae Kyoung Kwon
J. Microbiol. 2025;63(9):e2507003.   Published online September 30, 2025
DOI: https://doi.org/10.71150/jm.2507003
  • 1,593 View
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AbstractAbstract PDF

Marine organisms often form symbiotic relationships with various microorganisms to adapt and thrive in harsh environments. These symbiotic microbes contribute to host survival by providing nutrition, modulating the hosts’ immune system, and supporting overall physiological stability. Advances in high-throughput sequencing technologies have enabled a deeper understanding of the structure and function of symbiotic microbial communities, as well as host-microbe interactions. Notably, symbiotic bacteria associated with marine invertebrates such as corals and sponges are recognized as a potential source of useful bioactive compounds, including antibiotics and enzymes. However, obtaining high-quality microbial DNA from host tissues still remains a technical challenge due to the presence of unknown substances. This study focuses on optimizing sample preparation and DNA extraction procedures and additional purification to improve the recovery of microbial DNA while minimizing host DNA contamination. Comparison between several methods was conducted using sponge samples to evaluate DNA quality and microbial recovery. A sample designated as 2110BU-001 was collected from the east coast of the Republic of Korea and used for culture-independent microbial cell isolation. Total bacterial DNA was extracted by using a manual Phenol-Chloroform protocol and three commercial kits. DNA extracted using the standard manual method showed both the highest yield and the largest fragment size. However, PCR (Polymerase chain reaction) test showed that quality of manually extracted DNA was not enough for sequencing. Therefore, the quality of DNA was improved through additional purification steps. Briefly, host eukaryotic cells were removed by mechanical process and almost only bacterial DNA was successfully obtained by combination of manual extraction method and further purification processes. The established protocol was successfully introduced to extraction of metagenomic DNA from mussel and jellyfish microbiomes, indicating that it can be widely applied to various marine organisms.

Full articles
PhoU interaction with the PhoR PAS domain is required for repression of the pho regulon and Salmonella virulence, but not for polyphosphate accumulation
Seungwoo Baek, Soomin Choi, Yoontak Han, Eunna Choi, Shinae Park, Jung-Shin Lee, Eun-Jin Lee
J. Microbiol. 2025;63(9):e2505013.   Published online September 30, 2025
DOI: https://doi.org/10.71150/jm.2505013
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AbstractAbstract PDFSupplementary Material

The pho regulon plays a critical role in maintaining phosphate homeostasis in bacteria, with the PhoU protein functioning as a regulator that bridges the PhoB/PhoR two-component system and the PstSCAB2 phosphate transporter. While PhoU is known to suppress PhoR autophosphorylation under high phosphate conditions via interaction with its PAS domain, its broader regulatory functions remain elusive. Here, we investigated the role of the PhoU Ala147 residue in Salmonella enterica serovar Typhimurium using a phoUA147E substitution mutant. Bacterial two-hybrid and immunoprecipitation assays confirmed that Ala147 is essential for PhoU-PhoR PAS domain interaction, and its substitution leads to derepression of pho regulon genes, even in high phosphate conditions. This disruption impaired Salmonella survival inside macrophages and mouse virulence, demonstrating the importance of PhoU-PhoR interaction in Salmonella pathogenesis. However, unlike the phoU deletion mutant, the phoUA147E mutant does not exhibit growth defects or polyphosphate accumulation, indicating that the PhoU-PhoR interaction is not involved in these phenotypes. Our findings reveal PhoU as a multifaceted regulator, coordinating phosphate uptake and pho regulon expression through distinct molecular interactions, and provide new insights into its role in bacterial physiology and virulence.

Exploring the biosynthetic potential of Korean Actinobacteria for antibacterial metabolite discovery
Sehong Park, Hyun-Woo Je, Yujin Cha, Boncheol Gu, Yeojeong Cho, Jin-Il Kim, Ji Won Seo, Seung Bum Kim, Jino Son, Moonsuk Hur, Changmin Sung, Min-Kyu Oh, Hahk-Soo Kang
J. Microbiol. 2025;63(9):e2504002.   Published online September 30, 2025
DOI: https://doi.org/10.71150/jm.2504002
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Actinobacteria, a phylum of Gram-positive bacteria, are renowned for their remarkable ability to produce antibacterial natural products. The National Institute of Biological Resources (NIBR) of Korea maintains a collection of Korean native actinobacteria. In this study, we explored the phylogenetic and biosynthetic diversity of the NIBR actinobacteria collection to assess its potential as a source of new antibacterial natural products. A 16S rDNA-based phylogenetic analysis revealed a high level of genetic diversity within the collection, with a predominance of Streptomyces, along with rare actinobacterial genera such as Kitasatospora and Micromonospora. Additionally, genetic network analysis of biosynthetic gene clusters (BGCs) from 15 sequenced NIBR actinobacterial strains demonstrated extensive BGC diversity, with many clusters identified as cryptic. Screening of culture extracts for antibacterial activity, followed by dereplication of active extracts, suggested the presence of potentially novel antibacterial natural products. Activity-guided isolation and whole-genome sequencing of the active strain KU57 led to the isolation of one new and three known svetamycin congeners along with their BGC. Overall, our findings highlight the NIBR actinobacteria collection as a valuable source for the discovery of new antibacterial natural products.

Pycnogenol reduces the expression of P. aeruginosa T3SS and inflammatory response in NCI-H292 cells
Seung-Ho Kim, Da Yun Seo, Sang-Bae Han, Un-Hwan Ha, Ji-Won Park, Kyung-Seop Ahn
J. Microbiol. 2025;63(10):2503004.   Published online September 19, 2025
DOI: https://doi.org/10.71150/jm.2503004
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AbstractAbstract PDFSupplementary Material

Nosocomial infections caused by Pseudomonas aeruginosa (P. aeruginosa) have become increasingly common, particularly among immunocompromised individuals, who experience high mortality rates and prolonged treatment durations due to the limited availability of effective therapies. In this study, we screened for anti-ExoS compounds targeting P. aeruginosa and identified pycnogenol (PYC) as a potent inhibitor of the type III secretion system (T3SS), a major virulence mechanism responsible for the translocation of effectors such as ExoS. Using ELISA, western blotting, and real-time PCR analyses in both P. aeruginosa and infected H292 cells, we found that PYC significantly reduced T3SS activity. Mechanistically, PYC suppressed the transcription of T3SS-related genes by downregulating exsA expression in P. aeruginosa. Furthermore, pretreatment with PYC attenuated the cytotoxic effects and reduced the expression of proinflammatory cytokines, including interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-18 (IL-18), in P. aeruginosa-infected H292 cells. These effects were associated with the inhibition of NF-κB signaling and inflammasome activation. Taken together, our findings suggest that PYC may serve as a promising therapeutic candidate against P. aeruginosa infections by targeting T3SS-mediated virulence and modulating host inflammatory responses.

Detection system− and strain−dependent diversity of de novo [PSI+] prion generation and phenotypes in Saccharomyces cerevisiae
Moonil Son
J. Microbiol. 2025;63(10):e2506009.   Published online September 18, 2025
DOI: https://doi.org/10.71150/jm.2506009
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AbstractAbstract PDF

Yeast prion [PSI+], an amyloid form of the translation termination factor Sup35p/eRF3, causes translational stop codon readthrough by sequestering functional Sup35p. This unique phenotype may be analyzed via [PSI+]−suppressible nonsense alleles, and has greatly contributed to the advancement in yeast prion research. For comparing canonical reporters, like chromosomal ade1−14 or ade2−1, and plasmid-borne ura3−14, the de novo generation and characteristics of [PSI+] was investigated across common yeast laboratory strains (BY4741, 74D−694, and 779−6A). The results showed significant variability in [PSI+] induction frequency among strains. [PSI+] was successfully induced in BY4741 and frequently in 74D−694 (via Ade+ selection), but not in 779−6A. Notably, [PSI+] clones, even from identical genetic backgrounds, displayed vastly different nonsense suppression phenotypes depending on the reporter allele used; resulting in diverse growth patterns and suppression levels. Quantitative analyses revealed that prion seed counts fluctuated significantly based on the detection allele and observed phenotype. Furthermore, Sup35p aggregate visualization revealed distinct structural patterns between BY4741 and 74D−694, indicating strain-specific differences. Transferring [PIN+] prion variants from different strains into a common [psi−][pin−] background yielded similar [PSI+] inducibility and seed numbers, suggesting that the observed phenotypic and quantitative diversities of [PSI+] prions stem primarily from the interplay between the specific reporter detection system and the host strain's genetic background rather than solely from inherent differences in the initial [PIN+] prion or fundamental changes in the [PSI+] protein itself. This study underscores the crucial need to consider both the detection methodology and host genetic context for accurate prion variant characterization.

Crystal structures of the μ2 subunit of clathrin-adaptor protein 2 in complex with peptides derived from human papillomavirus 16 E7
Sujin Jung, Dahwan Lim, Joon Sig Choi, Ho-Chul Shin, Seung Jun Kim, Bonsu Ku
J. Microbiol. 2025;63(8):e2505003.   Published online August 31, 2025
DOI: https://doi.org/10.71150/jm.2505003
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AbstractAbstract PDF

Human papillomaviruses (HPVs) cause abnormal cellular proliferation, leading to malignant or benign lesions, such as cervical cancer and warts. The genome of HPV16, the most prevalent high-risk oncogenic genotype within the Alphapapillomavirus genus, encodes two oncoproteins. One of these proteins, E7, interacts with multiple host proteins and modulates their functions through distinct pathways. The CR2 domain of HPV16 E7 was recently reported to interact with the μ2 subunit of clathrin-adaptor protein 2 (AP2-μ2), an adaptor complex involved in cargo internalization during clathrin-mediated endocytosis. In this study, to provide molecular insights into their intermolecular interactions, we determined the crystal structures of AP2-μ2 in complex with the HPV16 E7-derived peptides. Subsequent biochemical analyses revealed that this interaction is primarily maintained by the Y-x-x-Φ motif and further supported by acidic cluster residues of HPV16 E7. Finally, sequence alignment of the E7 CR2 domains from various HPV genotypes showed that the AP2-μ2-binding motif is largely conserved in Alpha-, Beta-, and Mupapillomaviruses, but not in Nu- and Gammapapillomaviruses.

Review
CRISPR-Cas technologies: Emerging tools from research to clinical application
Hana Hyeon, Soonhye Hwang, Yongyang Luo, Eunkyoung Shin, Ji-Hyun Yeom, Hong-Man Kim, Minkyung Ryu, Kangseok Lee
J. Microbiol. 2025;63(8):e2504012.   Published online August 31, 2025
DOI: https://doi.org/10.71150/jm.2504012
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AbstractAbstract PDF

CRISPR-Cas technologies have emerged as powerful and versatile tools in gene therapy. In addition to the widely used SpCas9 system, alternative platforms including modified amino acid sequences, size-optimized variants, and other Cas enzymes from diverse bacterial species have been developed to apply this technology in various genetic contexts. In addition, base editors and prime editors for precise gene editing, the Cas13 system targeting RNA, and CRISPRa/i systems have enabled diverse and adaptable approaches for genome and RNA editing, as well as for regulating gene expression. Typically, CRISPR-Cas components are transported to the target in the form of DNA, RNA, or ribonucleoprotein complexes using various delivery methods, such as electroporation, adeno-associated viruses, and lipid nanoparticles. To amplify therapeutic efficiency, continued developments in targeted delivery technologies are required, with increased safety and stability of therapeutic biomolecules. CRISPR-based therapeutics hold an inexhaustible potential for the treatment of many diseases, including rare congenital diseases, by making permanent corrections at the genomic DNA level. In this review, we present various CRISPR-based tools, their delivery systems, and clinical progress in the CRISPR-Cas technology, highlighting its innovative prospects for gene therapy.

Full articles
Mouse strain-dependent neutralizing antibody responses to Zika virus vaccines
Sang Hwan Seo, Jung-ah Choi, Eunji Yang, Hayan Park, Dae-Im Jung, Jae-Ouk Kim, Jae Seung Yang, Manki Song
J. Microbiol. 2025;63(8):e2504005.   Published online August 31, 2025
DOI: https://doi.org/10.71150/jm.2504005
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AbstractAbstract PDF

The 2015 Zika virus (ZIKV) outbreak in Brazil and its global spread underscored the urgent need for effective and broadly protective vaccines. While C57BL/6 and BALB/c mice are widely used in preclinical vaccine research, direct comparisons of their ability to elicit ZIKV-specific neutralizing antibodies (nAbs) remain limited. This study aimed to systematically evaluate and compare the immunogenic potential of these two common mouse strains across diverse vaccine platforms, focusing on their capacity to generate functional neutralizing antibody responses. We assessed nAb and IgG responses following four vaccination strategies: (1) DNA vaccine encoding prMEΔTM followed by E protein domain III boost, (2) recombinant EΔTM protein expressed using baculovirus system, (3) formalin-inactivated ZIKV, and (4) live ZIKV. Although both strains generated detectable ZIKV- and E protein-specific IgG, the magnitude and quality of responses varied by vaccine platform and strain. Notably, C57BL/6 mice consistently mounted significantly higher nAb titers than BALB/c mice across all immunization groups, including subunit- and whole-virus-based vaccines. In contrast, BALB/c mice showed lower or undetectable nAb responses, despite comparable or higher total IgG levels in some cases. These findings show that host genetic background is a critical determinant of vaccine-induced neutralization and underscore the importance of selecting appropriate animal models in ZIKV vaccine development. C57BL/6 mice, due to their robust nAb responses, represent a reliable model for evaluating vaccine immunogenicity. Conversely, the limited nAb responses in BALB/c mice position them as a potential low-responder model, offering a stringent system to test the potency and breadth of protective immunity under suboptimal conditions.

Staphylococcus parequorum sp. nov. and Staphylococcus halotolerans sp. nov., isolated from traditional Korean soybean foods
Ju Hye Baek, Dong Min Han, Dae Gyu Choi, Chae Yeong Moon, Jae Kyeong Lee, Chul-Hong Kim, Jung-Woong Kim, Che Ok Jeon
J. Microbiol. 2025;63(8):e2503003.   Published online August 31, 2025
DOI: https://doi.org/10.71150/jm.2503003
Correction in: J. Microbiol 2025;63(9):e2509100 Correction in: J. Microbiol 2025;63(10):e2510101
  • 1,755 View
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AbstractAbstract PDFSupplementary Material

Strains Mo2-6T, S9, KG4-3T, and 50Mo3-2, identified as coagulase-negative, Gram-stain-positive, halotolerant, non-motile coccoid bacteria, were isolated from traditional Korean soybean foods. Strains Mo2-6T and S9 were both catalase- and oxidase-negative, whereas KG4-3T and 50Mo3-2 were catalase-positive but oxidase-negative. The optimal growth conditions for Mo2-6T and S9 were 30°C, 2% NaCl, and pH 7.0, while KG4-3T and 50Mo3-2 grew best at 35°C, 2% NaCl, and pH 7.0. All strains contained menaquinone-7 as the predominant isoprenoid quinone, with anteiso-C15:0 and iso-C15:0 as the major cellular fatty acids (> 10%). Additionally, anteiso-C13:0 was a major fatty acid in strain KG4-3T. The DNA G + C contents of strains Mo2-6T, S9, KG4-3T, and 50Mo3-2 were 33.4%, 33.3%, 32.5%, and 32.7%, respectively. Phylogenetic analyses based on the 16S rRNA gene and whole-genome sequences revealed that strains Mo2-6T and S9, as well as KG4-3T and 50Mo3-2, formed distinct lineages within the genus Staphylococcus. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) analyses confirmed that strains Mo2-6T and S9, as well as KG4-3T and 50Mo3-2, belonged to the same species. Meanwhile, dDDH and ANI values between strains Mo2-6T and KG4-3T, as well as comparisons with other Staphylococcus type strains, were below the species delineation thresholds, indicating they represent novel species. Based on phenotypic, chemotaxonomic, and molecular data, we propose strain Mo2-6T as the type strain of Staphylococcus parequorum sp. nov. (=KACC 23685T =JCM 37038T) and strain KG4-3T as the type strain of Staphylococcus halotolerans sp. nov. (=KACC 23684T =JCM 37037T).

Multi-omics to evaluate the protective mechanisms during Akkermansia muciniphila treatment of Candida albicans colonization and subsequent infection
Qiulin Luo, Huan Zhang, Youming Pu, Yingpu Wei, Jiangkun Yu, Xiaoshen Wang, Qin Cai, Ying Hu, Wenli Yuan
J. Microbiol. 2025;63(8):e2502007.   Published online August 31, 2025
DOI: https://doi.org/10.71150/jm.2502007
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AbstractAbstract PDFSupplementary Material

Akkermansia muciniphila (AKK, A. muciniphila) fortifies the intestinal barrier, inhibits the colonization of pathogenic bacteria, and protects the host’s health. Nevertheless, the existing literature offers inadequate evidence to ascertain whether A. muciniphila can effectively treat Candida albicans (C. albicans) infections in vitro, and the underlying mechanisms remain ambiguous. This study, animal models were established through gavage with clinical isolates of C. albicans to induce gastrointestinal tract colonization and subsequent translocation infection. The models were subsequently administered A. muciniphila. We examined the analysis of 16S rRNA gene sequencing, metabolomics of colonic contents, and transcriptomics of colonic tissue. The intestinal barrier, inflammatory responses, and immune cell infiltration are analyzed. This study revealed that A. muciniphila markedly mitigated C. albicans translocation infection and modified the intestinal microbial community structure and metabolic attributes in model mice. After administering A. muciniphila to the translocation infection group, there was a notable increase in the prevalence of bacteria that produce short-chain fatty acids, including Eubacterium_F. Moreover, there was a significant increase in the levels of specific pathogens, including Faecalibaculum, Turicibacter, and Turicimonas. The study demonstrated that A. muciniphila treatment can improve the composition of intestinal microbiota and metabolites, augment the tight junctions of colonic tissue and diminish systemic inflammatory response. This presents an innovative therapeutic approach for the potential treatment of intestinal C. albicans infection using A. muciniphila.

Metal ion homeostasis regulates condensin-dependent chromatin architecture and chromosome segregation in Schizosaccharomyces pombe
Seong Ho An, Kyoung-Dong Kim
J. Microbiol. 2025;63(9):e2505008.   Published online August 29, 2025
DOI: https://doi.org/10.71150/jm.2505008
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AbstractAbstract PDFSupplementary Material

Condensin plays a central role in mitotic chromosome organization and segregation by mediating long-range chromatin interactions. However, the extent to which cellular metabolic status influences condensin function remains unclear. To gain insights into the relationship of metal ion homeostasis and the function of condensin, we conducted genome-wide chromatin immunoprecipitation sequencing (ChIP-seq) using Schizosaccharomyces pombe under iron- or zinc-deficient conditions. Under iron- or zinc-deficient conditions, ChIP-seq results revealed a selective reduction in condensin binding at high-affinity target loci, particularly genes regulated by Ace2 and Ams2, while cohesin binding remained largely unaffected. Hi-C analysis showed that iron depletion weakened chromatin interactions at these condensin targets and centromeres, without disrupting global genome architecture. DNA fluorescence in situ hybridization (FISH) confirmed that iron deficiency impaired long-range associations between centromeres and Ace2 target loci at the single-cell level. Notably, iron deficiency led to chromosome segregation defects during mitosis, suggesting that diminished condensin occupancy compromised genome stability. These changes occurred without significant alterations in condensin protein levels or global transcription, indicating a direct effect of metal ion availability on condensin activity. Collectively, our findings revealed a previously unrecognized regulatory axis in which cellular metal ion homeostasis modulated condensin-dependent chromatin organization and mitotic chromosome segregation, offering new insights into the integration of metabolic state with genome maintenance.

Efficient CRISPR-based genome editing for inducible degron systems to enable temporal control of protein function in large double-stranded DNA virus genomes
Kihye Shin, Eui Tae Kim
J. Microbiol. 2025;63(9):e2504008.   Published online August 29, 2025
DOI: https://doi.org/10.71150/jm.2504008
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AbstractAbstract PDF

CRISPR-Cas9-based gene editing enables precise genetic modifications. However, its application to human cytomegalovirus (HCMV) remains challenging due to the large size of the viral genome and the essential roles of key regulatory genes. Here, we establish an optimized CRISPR-Cas9 system for precise labeling and functional analysis of HCMV immediate early (IE) genes. By integrating a multifunctional cassette encoding an auxin-inducible degron (AID), a self-cleaving peptide (P2A), and GFP into the viral genome via homology-directed repair (HDR), we achieved efficient knock-ins without reliance on bacterial artificial chromosome (BAC) cloning, a labor-intensive and time-consuming approach. We optimized delivery strategies, donor template designs, and component ratios to enhance HDR efficiency, significantly improving knock-in success rates. This system enables real-time fluorescent tracking and inducible protein degradation, allowing temporal control of essential viral proteins through auxin-mediated depletion. Our approach provides a powerful tool for dissecting the dynamic roles of viral proteins throughout the HCMV life cycle, facilitating a deeper understanding of viral pathogenesis and potential therapeutic targets.

Rubrivirga aquatilis sp. nov. and Rubrivirga halophila sp. nov., isolated from Korean coastal surface seawater
Jisoo Han, Yeonjung Lim, Mirae Kim, Jang-Cheon Cho
J. Microbiol. 2025;63(8):e2504017.   Published online August 13, 2025
DOI: https://doi.org/10.71150/jm.2504017
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AbstractAbstract PDFSupplementary Material

Two Gram-stain-negative, obligately aerobic, non-motile, short rod-shaped bacteria, designated IMCC43871T and IMCC45206T, were isolated from coastal surface seawater collected from the Yellow Sea and the South Sea of Korea, respectively. The two strains shared 99.2% 16S rRNA gene sequence similarity with each other and exhibited ≤ 98.4% similarity to three described Rubrivirga species. Average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between IMCC43871T and IMCC45206T were 88.5% and 36.3%, respectively, confirming that they represent two distinct species. Their ANI (≤ 77.7%) and dDDH (≤ 21.4%) values relative to the type strains of the genus Rubrivirga further supported the recognition of strains IMCC43871T and IMCC45206T as two novel species within the genus. The complete genomes of IMCC43871T (4.17 Mb, 71.8% G + C content) and IMCC45206T (4.17 Mb, 72.8% G + C content) fall within the known genomic range of the genus. Cellular fatty acid, quinone, and polar lipid profiles were consistent with the chemotaxonomic features of the genus Rubrivirga, supporting their affiliation with the genus. Based on phylogenetic, genomic, and phenotypic evidence, strains IMCC43871T and IMCC45206T are proposed as two novel species, Rubrivirga aquatilis sp. nov. and Rubrivirga halophila sp. nov., respectively. The type strains are IMCC43871T (= KCTC 102072T = NBRC 116463T) and IMCC45206T (= KCTC 92925T = NBRC 116172T = CCTCC AB 2023136T).

Review
Extracellular vesicles of Gram-negative and Gram-positive probiotics
Yangyunqi Wang, Chongxu Duan, Xiaomin Yu
J. Microbiol. 2025;63(7):e2506005.   Published online July 31, 2025
DOI: https://doi.org/10.71150/jm.2506005
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  • 1 Crossref
AbstractAbstract PDF

Extracellular vesicles derived from probiotics have received considerable attention for their pivotal role in bacterial‒host communication. These nanosized, bilayer-encapsulated vesicles carry diverse bioactive molecules, such as proteins, lipids, nucleic acids, and metabolites. Currently, ample evidence has emerged that probiotic extracellular vesicles may modulate several processes of host physiological hemostasis and offer therapeutic benefits. This review examines the biogenesis, composition, and immunomodulatory functions of probiotic-derived extracellular vesicles in probiotic–host interactions, highlighting the therapeutic potential of probiotic extracellular vesicles in the diagnosis and treatment of conditions such as cancer and inflammatory bowel disease. We further summarize the techniques for the separation and purification of extracellular vesicles, providing a methodological foundation for future research and applications. Although the field of probiotic extracellular vesicle research is still in its infancy, the prospects for their application in the biomedical field are broad, potentially emerging as a novel therapeutic approach.

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  • Standardizing Bacterial Extracellular Vesicle Purification: A Call for Consensus
    Dongsic Choi, Eun-Young Lee
    Journal of Microbiology and Biotechnology.2025;[Epub]     CrossRef
Full articles
Haloimpatiens sporogenes sp. nov. and Haloimpatiens myeolchijeotgali sp. nov., anaerobic bacteria isolated from Myeolchi-jeot, a traditional Korean fermented anchovy
Yu Jeong Lee, Byung Hee Chun
J. Microbiol. 2025;63(7):e2504009.   Published online July 31, 2025
DOI: https://doi.org/10.71150/jm.2504009
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AbstractAbstract PDFSupplementary Material

Two rod-shaped, Gram-positive, spore-forming, motile, and strictly anaerobic bacteria, FM7315T and FM7330T were isolated from Myeolchi-jeot, a traditional Korean fermented anchovy. Phylogenetic and phylogenomic analyses based on the 16S rRNA gene and genome sequences revealed that strains FM7315T and FM7330T represent novel species within the genus Haloimpatiens. The genome sizes of strains FM7315T and FM7330T were 3,052,517 bp and 4,194,114 bp, respectively, with G + C contents of 29.7 mol% and 28.0 mol%, respectively. Strain FM7315T exhibited growth at 20–37°C, 0–2% NaCl, and pH range of 5.0–8.0, whereas strain FM7330T grew at 25–45°C, 0–4% NaCl, and pH range of 5.0–9.0. Strain FM7315T contains C14:0, C16:0, C18:1 ω9c, Summed Feature 3 (C16:1 ω7c/C16:1 ω6c), and Summed Feature 8 (C18:1 ω7c/C18:1 ω6c) as major fatty acids, along with diphosphatidylglycerol, phosphatidylglycerol, glycolipid, two aminophospholipids, and five unidentified lipids. Strain FM7330T contains C16:0, C17:1 ω8c, and C18:1 ω9c as major fatty acids, along with diphosphatidylglycerol, two phosphatidylglycerols, four aminophospholipids, and six unidentified lipids. Based on their phenotypic, chemotaxonomic, and molecular characteristics, strains FM7315T and FM7330T represent two novel species of the genus Haloimpatiens, for which the names Haloimpatiens sporogenes sp. nov. (FM7315T = KCTC 25939T = JCM 37574T) and Haloimpatiens myeolchijeotgali sp. nov. (FM7330T = KCTC 25938T = JCM 37575T) have been proposed.

Prebiotic potential of proso millet and quinoa: Effects on gut microbiota composition and functional metabolic pathways
Jinwoo Kim, Jiwoon Kim, Yewon Jung, Gyungcheon Kim, Seongok Kim, Hakdong Shin
J. Microbiol. 2025;63(7):e2503002.   Published online July 31, 2025
DOI: https://doi.org/10.71150/jm.2503002
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AbstractAbstract PDFSupplementary Material

Prebiotics are indigestible dietary components that improve host health by stimulating the growth and metabolic activity of beneficial intestinal microbes. The whole grains are rich in non-digestible carbohydrates, which may confer prebiotic potential. Among them, millet and quinoa have gained attention as dietary alternatives due to the growing popularity of gluten-free diets. In this study, we examined the effects of proso millet and quinoa on the human gut microbiota using an in vitro fecal incubation model. Both grains altered alpha diversity metrics, including microbial richness, evenness, and phylogenetic diversity. Beta diversity analysis showed that the proso millet and quinoa treatment groups exhibited distinct clustering patterns compared to the control, highlighting their impact on microbial community structure. Taxonomic analysis showed an increase in beneficial genera, including Bifidobacterium, and a decrease in taxa such as Enterobacteriaceae and Flavonifractor. To assess metabolic changes associated with microbial fermentation, short-chain fatty acid (SCFA) intensities were measured. The intensities of acetic acid, propionic acid, and butyric acid were significantly higher in the proso millet- and quinoa-treated groups compared to the control group. Spearman correlation analysis showed that the abundances of Bifidobacterium and Blautia were significantly positively associated with SCFA intensities. Furthermore, predicted functional pathway analysis identified enrichment of carbohydrate-related pathways in proso millet and quinoa treatments. Quinoa supplementation led to a broader enhancement of metabolic pathways, including glycolysis/gluconeogenesis, starch and sucrose metabolism, and pentose phosphate pathways, whereas proso millet enriched galactose metabolism, and starch and sucrose metabolism. These findings suggest that proso millet and quinoa influence gut microbial diversity, composition, and function.

Review
Metabolic engineering of Saccharomyces cerevisiae for efficient utilization of pectin-rich biomass
Dahye Lee, Fransheska Semidey, Luping Xu, Eun Joong Oh
J. Microbiol. 2025;63(7):e2503001.   Published online July 31, 2025
DOI: https://doi.org/10.71150/jm.2503001
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AbstractAbstract PDF

Pectin-rich biomass, derived from fruit and citrus processing waste, presents a promising yet underutilized resource for sustainable biofuel and biochemical production. Its low lignin content and high concentrations of fermentable sugars, including D-galacturonic acid, L-arabinose, and D-xylose, make it an attractive feedstock. Unlike lignocellulosic biomass, pectin-rich hydrolysates require milder pretreatment, improving sugar recovery efficiency. However, industrial strains such as Saccharomyces cerevisiae exhibit strong glucose preference, limiting the efficient co-fermentation of mixed sugars. While prior reviews have broadly addressed lignocellulosic biomass utilization, this mini-review uniquely centers on the specific metabolic challenges and opportunities associated with pectin-rich feedstocks. In addition to incorporating established strategies for the co-utilization of cellobiose and xylose, we highlight recent advances that allow S. cerevisiae to metabolize carbon sources specifically from pectin-rich biomass, such as L-arabinose and D-galacturonic acid—monomers not prevalent in traditional lignocellulosic biomass. By integrating discussions on sugar transport engineering, redox balancing, and pathway optimization, this review offers a comprehensive framework to overcome glucose repression and support efficient co-fermentation of carbon sources from conventional and pectin-rich biomass. Drawing on these advances, we outline practical strategies to enhance fermentation performance and expand the valorization of food processing residues in biomanufacturing.

Full articles
Efficient and modular reverse genetics system for rapid generation of recombinant severe acute respiratory syndrome coronavirus 2
Sojung Bae, Jinjong Myoung
J. Microbiol. 2025;63(7):e2504015.   Published online July 21, 2025
DOI: https://doi.org/10.71150/jm.2504015
  • 2,955 View
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AbstractAbstract PDF

The global spread of COVID-19 has underscored the urgent need for advanced tools to study emerging coronaviruses. Reverse genetics systems have become indispensable for dissecting viral gene functions, developing live-attenuated vaccine candidates, and identifying antiviral targets. In this study, we describe a robust and efficient reverse genetics platform for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The system is based on the assembly of a full-length infectious cDNA clone from seven overlapping fragments, each flanked by homologous sequences to facilitate seamless assembly using the Gibson assembly method. Individual cloning of each fragment into plasmids enables modular manipulation of the viral genome, allowing rapid site-directed mutagenesis by fragment exchange. Infectious recombinant virus was successfully recovered from the assembled cDNA, exhibiting uniform plaque morphology and genetic homogeneity compared to clinical isolates. Additionally, fluorescent reporter viruses were generated to enable real-time visualization of infection, and the effects of different mammalian promoters on viral rescue were evaluated. This reverse genetics platform enables efficient generation and manipulation of recombinant SARS-CoV-2, providing a valuable resource for virological research and the development of preventive and therapeutic antiviral measures.

Inhibition of candidalysin production by methoxy-apo-enterobactin from Streptomyces ambofaciens CJD34 as a novel antifungal strategy against Candida albicans
Eui-Seong Kim, Hyeongju Jeong, Mustansir Abbas, Soohyun Um, Juntack Oh, Kyuho Moon, Kyung-Tae Lee
J. Microbiol. 2025;63(6):e2504019.   Published online June 30, 2025
DOI: https://doi.org/10.71150/jm.2504019
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AbstractAbstract PDF

Opportunistic fungal pathogens, responsible for over 300 million severe cases and 1.5 million deaths annually, pose a serious global health threat, especially in immunocompromised individuals. Among these, Candida albicans is a major cause of both superficial and invasive infections, which can progress to systemic candidiasis. One of the critical factors in C. albicans pathogenicity is the yeast-to-hyphal transition, which enables biofilm formation and promotes tissue invasion through the secretion of candidalysin, a cytolytic peptide toxin encoded by the ECE1 gene. In this study, metabolites produced by Streptomyces ambofaciens CJD34, isolated from soil samples, were screened for antifungal activity. Methoxy-apo-enterobactin (compound 1) was identified as a potential inhibitor of C. albicans virulence. Treatment with compound 1 significantly suppressed ECE1 expression and candidalysin production. In a murine subcutaneous infection model, topical application of compound 1 reduced subcutaneous colonization by C. albicans. Molecular docking analysis suggested that the inhibition of ECE1 expression was not mediated by direct binding to known upstream transcription factors, indicating an indirect mechanism of action. Collectively, these findings highlight compound 1 as a promising antivirulence agent targeting candidalysin-mediated pathogenicity in C. albicans.

Phycobium rhodophyticola gen. nov., sp. nov. and Aliiphycobium algicola gen. nov., sp. nov., isolated from the phycosphere of marine red algae
Jeong Min Kim, Woonhee Baek, Byeong Jun Choi, Hülya Bayburt, Jae Kyeong Lee, Sung Chul Lee, Che Ok Jeon
J. Microbiol. 2025;63(6):e2503014.   Published online June 30, 2025
DOI: https://doi.org/10.71150/jm.2503014
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AbstractAbstract PDFSupplementary Material

Two Gram-stain-negative, strictly aerobic, non-motile, rod-shaped bacteria, designated D3-12ᵀ and G2-2ᵀ, were isolated from the phycosphere of marine red algae. Both strains exhibited catalase- and oxidase-positive activities. Strain D3-12ᵀ grew optimally at 30°C, pH 7.0, and 2.0–3.0% (w/v) NaCl, while strain G2-2ᵀ showed optimal growth at 30°C, pH 7.0, and 2.0% NaCl. Ubiquinone-10 was the sole respiratory quinone in both strains. The major fatty acids (> 5%) in strain D3-12ᵀ were feature 8 (C18:1 ω7c and/or C18:1 ω6c), 11-methyl-C18:1 ω7c, and C16:0, while strain G2-2ᵀ contained summed feature 8 and C16:0. The predominant polar lipids in strain D3-12ᵀ were phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine, whereas strain G2-2ᵀ contained phosphatidylglycerol and diphosphatidylglycerol. The genomic DNA G + C content was 59.9% for strain D3-12ᵀ and 60.2% for strain G2-2ᵀ. Phylogenetic analyses based on 16S rRNA and whole-genome sequences placed both strains into distinct lineages within the family Roseobacteraceae, separate from previously described genera. Genome-based relatedness metrics, including average nucleotide identity, digital DNA-DNA hybridization, average amino acid identity, and percentage of conserved proteins, further confirmed that these strains represent novel genera. Based on phenotypic, chemotaxonomic, and molecular characteristics, strains D3-12ᵀ and G2-2ᵀ are proposed as novel genera: Phycobium rhodophyticola gen. nov., sp. nov. (D3-12ᵀ = KACC 22712ᵀ = JCM 35528ᵀ) and Aliiphycobium algicola gen. nov., sp. nov. (G2-2ᵀ = KACC 22602ᵀ = JCM 35752ᵀ). Additionally, metabolic features relevant to interactions with marine algae, including genes associated with carbohydrate-active enzymes, vitamin biosynthesis, phenylacetic acid production, and bacterioferritin synthesis, were bioinformatically investigated.

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  • Aquimarina rhodophyticola sp. nov. and Aquimarina besae sp. nov., Isolated from Marine Red Algae
    Jeong Min Kim, Byeong Jun Choi, Hülya Bayburt, Dong Min Han, Che Ok Jeon
    Current Microbiology.2025;[Epub]     CrossRef
  • Carotenoid-Producing Qipengyuania algicola sp. nov. and Qipengyuania rhodophyticola sp. nov., Isolated from Marine Algae, and Emended Description of the Genus Qipengyuania Xu et al. 2020
    Jae Kyeong Lee, Min Woo Lee, Chae Yeong Moon, Jeong Min Kim, Hülya Bayburt, Byeong Jun Choi, Che Ok Jeon
    Journal of Microbiology and Biotechnology.2025;[Epub]     CrossRef
Review
Targeting innate immune sensors for therapeutic strategies in infectious diseases
Seyun Shin, Young Ki Choi, SangJoon Lee
J. Microbiol. 2025;63(6):e2503009.   Published online June 30, 2025
DOI: https://doi.org/10.71150/jm.2503009
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  • 2 Web of Science
AbstractAbstract PDF

The innate immune system relies on innate immune sensors, such as pattern recognition receptors (PRRs), to detect pathogens and initiate immune responses, crucial for controlling infections but also implicated in inflammatory diseases. These innate immune sensors, including Toll-like receptors (TLRs), nod-like receptors (NLRs), RIG-I-like receptors (RLRs), absent in melanoma 2 (AIM2), and Z-DNA binding protein 1 (ZBP1) trigger signaling pathways that produce cytokines, modulating inflammation and cell death. Traditional therapies focus on directly targeting pathogens; however, host-targeting therapeutic strategies have emerged as innovative approaches to modulate innate immune sensor activity. These strategies aim to fine-tune the immune response, either enhancing antiviral defenses or mitigating hyperinflammation to prevent tissue damage. This review explores innate immune sensor-based therapeutic approaches, including inhibitors, agonists, and antagonists, that enhance antiviral defense or suppress harmful inflammation, highlighting innate immune sensors as promising targets in infectious and inflammatory disease treatment.

Full articles
Inhibiting kinesin family member 20A disrupts Zika virus entry by blocking internalization
Jeonghyeon Lee, Younghyun Lim, Hyeong-Rae Kim, Yong-Bin Cho, In-Gu Lee, Young-Jin Seo
J. Microbiol. 2025;63(6):e2503008.   Published online June 30, 2025
DOI: https://doi.org/10.71150/jm.2503008
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AbstractAbstract PDFSupplementary Material

Zika virus, a mosquito-borne virus, is associated with congenital birth defects and neurological complications. However, despite its significant public health threat, no approved vaccines or antiviral treatments are currently available. Therefore, this study aims to identify kinesin family member 20A as a key host factor promoting Zika virus life cycle. The elevated expression of kinesin family member 20A following Zika virus infection suggests its role in the viral life cycle. Suppressing its expression through gene silencing or inhibiting its function with a small-molecule inhibitor significantly reduced viral infectivity in host cells. Furthermore, kinesin family member 20A is essential for facilitating viral internalization, a key step in the entry step. These findings suggest its significance in the Zika virus life cycle and highlight its potential as a novel therapeutic target for the Zika virus.

Development of a CRISPR/Cas9 RNP-mediated genetic engineering system in Paecilomyces variotii
Hui-Gang Han, Rutuja Nandre, Hyerang Eom, Yeon-Jae Choi, Hyeon-Su Ro
J. Microbiol. 2025;63(6):e2502011.   Published online June 30, 2025
DOI: https://doi.org/10.71150/jm.2502011
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AbstractAbstract PDFSupplementary Material

A thermophilic strain of Paecilomyces variotii (MR1), capable of surviving temperatures above 40°C, was isolated from a paper mill and investigated as a host for heterologous protein production. To prevent environmental dissemination of spores, UV mutagenesis was employed to create a conidia-deficient strain, UM7. This strain underwent gene editing using Cas9-gRNA ribonucleoprotein (RNP) with HR donor DNA fragments, incorporating promoter sequences amplified from the genomic DNA of P. variotii (PH4, PP2, PS8, Ptub, Ptef1, and PgpdA), along with a signal sequence-tagged eGFP, flanked by 5’-upstream (336 bp) and 3’-downstream (363 bp) regions of pyrG. Co-transformation of HR donor DNA with RNP into protoplasts yielded 48 mutant pyrG transformants capable of surviving in the presence of 5-fluoroorotic acid (5-FOA). Sequence analysis identified 16 of the 48 pyrG-disrupted mutants carrying complete HR donor DNAs with the six different promoter sequences, indicating successful homology-directed repair (HDR). Evaluation of promoter strength revealed that PgpdA was the most effective for intracellular GFP production; however, it resulted in negligible extracellular GFP signal under all promoter conditions. A newly edited strain with an HDR integration module connecting PgpdA directly to eGFP, without the signal sequence, exhibited enhanced GFP expression in both mycelial cells and culture broth, suggesting that the signal peptide negatively affect protein expression and secretion. This work represents the first successful RNP-mediated gene editing in P. variotii, contributing to the application of this thermophilic fungus in protein production.

Bacteroides celer sp. nov. and Bacteroides mucinivorans sp. nov., isolated from human feces, and the reclassification of Bacteroides koreensis Shin et al. 2017 and Bacteroides kribbi Shin et al. 2017 as later heterotypic synonyms of Bacteroides ovatus Eggerth and Gagnon 1933 (Approved Lists 1980)
Ah-In Yang, Bora Kim, Woorim Kang, Hae-In Joe, Na-Ri Shin
J. Microbiol. 2025;63(6):e2502006.   Published online June 30, 2025
DOI: https://doi.org/10.71150/jm.2502006
Correction in: J. Microbiol 2025;63(7):e2507100
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Two novel, Gram-stain-negative, anaerobic, and non-motile bacterial strains, designated KFT8T and CG01T, were isolated from the feces of healthy individuals without diagnosed diseases and characterized using a polyphasic approach. Phylogenetic analysis revealed that both strains belong to the genus Bacteroides, with < 99.0% similarity in their 16S rRNA gene sequences to B. facilis NSJ-77T and B. nordii JCM 12987T. Within the genus Bacteroides, strain KFT8T exhibited the highest Orthologous Average Nucleotide Identity value of 94.7% and a digital DNA-DNA hybridization value of 63.7% with B. ovatus ATCC 8483T, whereas strain CG01T showed the highest values of 95.3% and 63.3%, respectively, with B. nordii JCM 12987T. The values between the two novel strains were 74.8% and 21.4%, respectively, which are below the species delineation thresholds, supporting their classification as novel species. The major fatty acid of strain KFT8T was C18:1 ω9c, whereas strain CG01T predominantly contained summed feature 11 (comprising iso-C17:0 3OH and/or C18:2 DMA). The only respiratory quinone was MK-11, the major polar lipid was phosphatidylethanolamine. Both strains produced succinic acid and acetic acid as common metabolic end-products of fermentation, while lactic acid and formic acid were detected individually in each strain. Based on polyphasic characterization, strains KFT8T (= KCTC 15614T = JCM 36011T) and CG01T (= KCTC 15613T = JCM 36010T) represent two novel species within the genus Bacteroides, for which the names Bacteroides celer sp. nov. and Bacteroides mucinivorans sp. nov. are proposed, respectively. Additionally, genome-based analyses and phenotypic comparisons revealed that B. koreensis and B. kribbi represent the same strain, showing genomic relatedness to B. ovatus that exceeds the threshold for species delineation. Consequently, we propose the reclassification of B. koreensis Shin et al. 2017 and B. kribbi Shin et al. 2017 as later heterotypic synonyms of B. ovatus Eggerth and Gagnon 1933 (Approved Lists 1980).

Microbial signatures in oral sites of patients with primary Sjögren’s syndrome: Association with salivary gland hypofunction
Sarah Kamounah, Arjun Sarathi, Christiane Elisabeth Sørensen, Manimozhiyan Arumugam, Anne Marie Lynge Pedersen
J. Microbiol. 2025;63(6):e2501030.   Published online June 30, 2025
DOI: https://doi.org/10.71150/jm.2501030
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This study aimed to determine if the microbiota in four different oral sites and the oral health status differ between patients with primary Sjögren’s syndrome (pSS), non-pSS sicca symptoms, and healthy controls. All participants underwent an interview and clinical oral examination. Stimulated whole saliva (SWS), supragingival plaque (SGP), buccal mucosa tissue (BLM), and tongue scrape (TGS) samples from 23 pSS patients, 36 patients with sicca symptoms, not fulfilling the classification criteria for pSS (non-pSS sicca), and 21 age-matched healthy controls (HC) were analyzed using V3–V4 16S rRNA gene amplicon sequencing, and determination of amplicon sequence variants (ASVs). PSS and non-pSS sicca patients did not differ with respect to oral health status, saliva flow rates, abundance of predominant genera, relative abundance on genus level or bacterial diversity in any of the oral sites. Both patient groups differed significantly from the healthy control group in the abundance of 61 ASVs across all sites. The alpha-diversity was lower in SGP from non-pSS sicca patients (p = 0.019), and in TGS from pSS patients (p = 0.04). The proportion of variation in the beta-diversity across all four sites could be explained by the diagnosis (pSS, non-pSS sicca, and HC). However, subgrouping of patients according to their stimulated salivary flow rates (SWS > 0.7 ml/min versus SWS ≤ 0.7 ml/min), revealed significantly different abundance of three ASVs in SWS, 11 in SGP, and six in TGS. Our findings suggest that hyposalivation rather than pSS itself modifies the microbial composition in oral site-specific patterns leading to oral diseases.

The photosensitizer DH-I-180-3 regulates intracellular bacterial growth by increasing the secretion of proinflammatory cytokines via the NF-κB- and MAPK-mediated signaling pathways and promoting phagosome maturation in Salmonella-infected mouse macrophages
Hyo-Jung Kim, Eui-Kwon Jeong, Hyo-Ji Lee, Yu-Jin Jung
J. Microbiol. 2025;63(6):e2502003.   Published online June 4, 2025
DOI: https://doi.org/10.71150/jm.2502003
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AbstractAbstract PDF

Photodynamic therapy (PDT) is a known strategy for treating cancer; in PDT, photosensitizers are activated by light stimulation and then induce reactive oxygen species (ROS) production to damage cancer tissues. Recently evidence has shown that PDT can also be used as a novel treatment strategy to control pathogenic bacteria. In previous studies, the photosensitizer DH-I-180-3 was reported to effectively regulate multidrug-resistant Mycobacterium tuberculosis growth. Here, we confirmed the effects of DH-I-180-3 on the antibacterial activity and inflammatory response of macrophages to Salmonella. Photoactivated DH-I-180-3 regulated intracellular bacterial growth in Salmonella-infected macrophages. Moreover, DH-I-180-3 increased intracellular ROS levels in Salmonella-infected macrophages. The phosphorylation of the intracellular signaling proteins IκBα and JNK1/2 was increased in DH-I-180-3-treated Salmonella-infected macrophages. Additionally, we observed that DH-I-180-3 significantly increased the mRNA expression and protein secretion of the proinflammatory cytokine TNF-α and promoted phagosome maturation by upregulating EEA1, LAMP1, and Cathepsin D in Salmonella-infected macrophages. Overall, these results demonstrate that photoactivated DH-I-180-3 enhances the bactericidal response to intracellular bacterial infection by promoting inflammatory signaling pathways and phagosome maturation. Therefore, DH-I-180-3 has the potential to be developed into PDT for treating bacterial-infection.

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  • Transcriptome Analysis Reveals Circadian Rhythmic Regulation of Lipid Metabolism and Immune Function in Chicken Livers
    Jiahua Li, Jie Dong, Minjie Huang, Yuting Jin, Xiaodong Tan, Deqian Wang
    Animals.2025; 15(22): 3241.     CrossRef
Role of the LAMMER kinase LkhA in fungal development and aflatoxin production in Aspergillus flavus
Seong-Hwan Jeong, He-Jin Cho, Jae-Hyuk Yu, Hee-Moon Park, Hee-Soo Park
J. Microbiol. 2025;63(5):e2503007.   Published online May 27, 2025
DOI: https://doi.org/10.71150/jm.2503007
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A well-conserved LAMMER kinase in yeast and filamentous fungi, is a dual-specificity kinase with multiple roles in fungal biology. In this study, we assessed the roles of LkhA in Aspergillus flavus, a toxigenic fungus that produces aflatoxin B1. lkhA deletion mutants exhibited defects in fungal growth, conidiophore development, and sclerotia formation. These mutants exhibited impaired tolerance to oxidative and cell wall stresses. Moreover, the absence of lkhA resulted in a decrease in aflatoxin B1 production. The kernel assay revealed that the lkhA deletion mutants exhibited reduced production of conidia and aflatoxin B1, implying that LkhA can affect fungal toxigenesis and pathogenicity. Taken together, these results demonstrate that LkhA is important for differentiation, mycotoxin production, and pathogenicity in A. flavus.

Characterization of novel bacteriophages for effective phage therapy against Vibrio infections in aquaculture
Kira Moon, Sangdon Ryu, Seung Hui Song, Se Won Chun, Nakyeong Lee, Aslan Hwanhwi Lee
J. Microbiol. 2025;63(5):e2502009.   Published online May 27, 2025
DOI: https://doi.org/10.71150/jm.2502009
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AbstractAbstract PDFSupplementary Material

The widespread use of antibiotics in aquaculture has led to the emergence of multidrug-resistant pathogens and environmental concerns, highlighting the need for sustainable, eco-friendly alternatives. In this study, we isolated and characterized three novel bacteriophages from aquaculture effluents in Korean shrimp farms that target the key Vibrio pathogens, Vibrio harveyi, and Vibrio parahaemolyticus. Bacteriophages were isolated through environmental enrichment and serial purification using double-layer agar assays. Transmission electron microscopy revealed that the phages infecting V. harveyi, designated as vB_VhaS-MS01 and vB_VhaS-MS03, exhibited typical Siphoviridae morphology with long contractile tails and icosahedral heads, whereas the phage isolated from V. parahaemolyticus (vB_VpaP-MS02) displayed Podoviridae characteristics with an icosahedral head and short tail.

Whole-genome sequencing produced complete, circularized genomes of 81,710 bp for vB_VhaS-MS01, 81,874 bp for vB_VhaS-MS03, and 76,865 bp for vB_VpaP-MS02, each showing a modular genome organization typical of Caudoviricetes. Genomic and phylogenetic analyses based on the terminase large subunit gene revealed that although vB_VhaS-MS01 and vB_VhaS-MS03 were closely related, vB_VpaP-MS02 exhibited a distinct genomic architecture that reflects its unique morphology and host specificity. Collectively, these comparative analyses demonstrated that all three phages possess genetic sequences markedly different from those of previously reported bacteriophages, thereby establishing their novelty. One-step growth and multiplicity of infection (MOI) experiments demonstrated significant differences in replication kinetics, such as burst size and lytic efficiency, among the phages, with vB_VhaS-MS03 maintaining the most effective bacterial control, even at an MOI of 0.01. Additionally, host range assays showed that vB_VhaS-MS03 possessed a broader spectrum of activity, supporting its potential use as a stand-alone agent or key component of phage cocktails. These findings highlight the potential of region-specific phage therapy as a targeted and sustainable alternative to antibiotics for controlling Vibrio infections in aquaculture.

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  • Feed Additives in Aquaculture: Benefits, Risks, and the Need for Robust Regulatory Frameworks
    Ekemini Okon, Matthew Iyobhebhe, Paul Olatunji, Mary Adeleke, Nelson Matekwe, Reuben Okocha
    Fishes.2025; 10(9): 471.     CrossRef
Antiviral effects of heme oxygenase-1 against canine coronavirus and canine influenza virus in vitro
Jae-Hyeong Kim, Dong-Hwi Kim, Kyu-Beom Lim, Joong-Bok Lee, Seung-Yong Park, Chang-Seon Song, Sang-Won Lee, Dong-Hun Lee, Do-Geun Kim, Hun-Young Yoon, In-Soo Choi
J. Microbiol. 2025;63(5):e2501029.   Published online May 27, 2025
DOI: https://doi.org/10.71150/jm.2501029
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Heme oxygenase-1 (HO-1) has antioxidant, anti-apoptotic, and anti-inflammatory properties. Emerging evidence shows that HO-1 also exhibits antiviral activity against severe acute respiratory syndrome coronavirus 2, human immunodeficiency virus, hepatitis B virus, and Ebola virus. Its antiviral effects are mediated not only by its enzymatic function but also through the modulation of interferon-related pathways, thereby inhibiting viral replication. In this study, we investigated the antiviral effects of HO-1 on canine coronavirus (CCoV) and canine influenza virus (CIV) H3N2 using cell-based assays. To determine whether HO-1 suppresses CCoV and CIV, cells were treated with hemin to induce HO-1 expression. Hemin treatment successfully induced HO-1 expression in A72 and Madin-Darby canine kidney cells, resulting in the suppression of CCoV and CIV replication. The canine HO-1 gene was cloned into an expression vector and transfected into cells to achieve transient overexpression. Recombinant canine HO-1 protein was expressed in Escherichia coli and purified using an expression vector. HO-1 overexpression suppressed CCoV and CIV replication in cells. Following viral infection, treatment with purified HO-1 protein led to a reduction in viral protein levels. Therefore, both HO-1 expression and exogenous protein treatment effectively inhibited CCoV and CIV replication. Elevated HO-1 protein levels consistently reduced viral RNA and protein expression in vitro. These findings suggest that HO-1 could serve as a potential therapeutic agent for managing viral infections in dogs.

Microbiome therapeutic PMC72 through reverse translational research in gout
Mohammed Solayman Hossain, Hoonhee Seo, Kyung-Ann Lee, Asad ul-Haq, Sukyung Kim, Sujin Jo, Md Abdur Rahim, Hanieh Tajdozian, Fatemeh Ghorbanian, Youjin Yoon, Indrajeet Barman, Md Sarower Hossen Shuvo, Hyun-Sook Kim, Ho-Yeon Song
J. Microbiol. 2025;63(5):e2501002.   Published online May 27, 2025
DOI: https://doi.org/10.71150/jm.2501002
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AbstractAbstract PDFSupplementary Material

Gout is an inflammatory arthritis resulting from the deposition of monosodium urate crystals. Urate-lowering therapies for gout have limitations, including side effects and limited efficacy, highlighting the need for novel therapeutic approaches to improve patient outcomes. In this context, our research team conducted a microbiome analysis of fecal samples from healthy individuals and gout patients, identifying Bifidobacterium as a key biomarker. Subsequently, we isolated and identified this strain, B. longum PMC72, and demonstrated its efficacy in a gout mouse model. In potassium oxonate (PO)-induced hyperuricemia mice, PMC72 significantly alleviated nausea, gait disturbances, ankle inflammation, and improved renal health. These effects were associated with marked reductions in oxidative stress markers, including serum uric acid, blood urea nitrogen, hepatic xanthine oxidase, and malondialdehyde (MDA) levels in serum, liver, and joint samples, as well as the downregulation of inflammation and uric acid transport-related gene expression in kidney samples. These benefits were comparable to those treated with Febuxostat, a standard urate-lowering therapy for gout. Furthermore, gut microbiome analysis revealed that PMC72 restored dysbiosis induced by hyperuricemia, contrasting with the reduced microbial diversity observed with febuxostat alone, and showed a complete recovery to eubiosis when combined with Febuxostat. These findings position PMC72 as a promising microbial therapeutic candidate for gout management, demonstrating significant development potential and serving as a benchmark for reverse translational microbiome-based therapeutic research.

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  • Characterization of Gut Microbiota of Honey Bees in Korea
    Md Sarower Hossen Shuvo, Sukyung Kim, Sujin Jo, Md Abdur Rahim, Indrajeet Barman, Mohammed Solayman Hossain, Yoonkyoung Jeong, Hwasik Jeong, Sangrim Kim, Hoonhee Seo, Ho-Yeon Song
    Polish Journal of Microbiology.2025;[Epub]     CrossRef
  • Quantitative assessment of microbial dynamics in livestock manure and municipal wastewater treatment plants
    Geon Choi, Hokyung Song, Tatsuya Unno
    Applied Biological Chemistry.2025;[Epub]     CrossRef
Time-resolved analysis of Bacillus subtilis DB104 Spo0A-mutant transcriptome profile and enhancement of recombinant protein release
Ji-Su Jun, Soo Ji Kang, Kwang-Won Hong
J. Microbiol. 2025;63(5):e2411032.   Published online May 27, 2025
DOI: https://doi.org/10.71150/jm.2411032
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Spo0A, the master regulator of sporulation initiation in Bacillus subtilis, controls over 500 genes directly or indirectly in early sporulation stages. Although the effects of Spo0A disruption on sporulation have been extensively studied, a comprehensive understanding of the genomic response throughout growth phases remain elusive. Here, we examined the transcriptomic changes in Spo0A mutant strain, R211E, and wild-type across a time-course RNA-seq to identify impacted biological processes and pathways. The R211E strain, which exhibits sporulation deficiency, was constructed using the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR associated protein (Cas)9 system, highlighting the critical role of proper Cas9 dosing in gene editing. Functional analysis of 3,010 differentially expressed genes (DEGs) showed significant alterations in sporulation, quorum sensing, metabolism, and biofilm formation. The R211E disrupted the Spo0A-AbrB regulatory pathway, reducing biofilm formation and enhancing flagellar gene expression. Up-regulated metabolic pathways, including glycolysis, histidine, and purine biosynthesis, increased cell numbers during vegetative growth. Further, the mutant displayed elevated vegetative autolysin expression, resulting in reduced cell viability in the stationary phase. We also introduce the novel potential of R211E in a recombinant protein expression system that facilitated protein release into the supernatant, providing valuable insight for future research in metabolic engineering and efficient production systems in B. subtilis.

Glucose affects capsular polysaccharides synthesis via CcpA and HPr in Streptococcus pneumoniae
Rui Yang, Yapeng Zhang, Hong Wang, Hanyi Wang, Jiangming Xiao, Lian Li, Yuan Yuan, Yibing Yin, Xuemei Zhang
J. Microbiol. 2025;63(5):e2411024.   Published online May 27, 2025
DOI: https://doi.org/10.71150/jm.2411024
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AbstractAbstract PDFSupplementary Material

Streptococcus pneumoniae is a conditionally pathogenic bacteria that colonizes the nasopharynx of 27% to 65% of children and 10% of adults. Capsular polysaccharides are the most critical virulence factor of S. pneumoniae, and nonencapsulated strains are usually non-pathogenic. Previous studies have shown that glucose regulates capsule synthesis. To investigate the mechanism of carbon metabolism regulatory factors CcpA and HPr regulating capsule synthesis in the presence of glucose as the sole carbon source, we constructed deletion mutants (D39ΔccpA and ΔptsH) and complemented strains (D39ΔccpA::ccpA and ΔptsH::ptsH). In this study, we found that the promoting effect of capsule synthesis by glucose disappeared after the deletion of ccpA and ptsH, and demonstrated that the protein CcpA regulates capsule synthesis by binding to the cps promoter and altering the transcription level of the cps gene cluster. Increased glucose concentration up-regulated the level of HPr-Ser46~P, which enhanced the binding ability of CcpA to the DNA sequence of the cps promoter, thus promoting capsule synthesis. HPr also has a regulatory effect on capsule synthesis. These insights reveal a new synthesis mechanism of capsular polysaccharide and provide a new strategy of antibacterial drugs for S. pneumoniae.

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  • The metabolic, microbial and immunological demands of pneumococcal colonisation
    Daniel R. Neill, Thomas B. Clarke, N.Luisa Hiller
    PLOS Pathogens.2025; 21(11): e1013675.     CrossRef
Alizarin, which reduces ExoS, attenuates inflammation by P. aeruginosa in H292 cells
Seung-Ho Kim, Hye In Ahn, Jae-Hoon Oh, Da Yun Seo, Jung-Hee Kim, Ok-kyoung Kwon, Ji-Won Park, Kyung-Seop Ahn
J. Microbiol. 2025;63(5):e2411012.   Published online May 27, 2025
DOI: https://doi.org/10.71150/jm.2411012
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AbstractAbstract PDF

Pseudomonas aeruginosa (P. aeruginosa) is resistant to several drugs as well as antibiotics and is thus classified as multidrug resistant and extensively drug resistant. These bacteria have a secretion system called the "type 3 secretion system (T3SS)", which facilitates infection by delivering an effector protein. ExoenzymeS (ExoS) is known to induce cell death and activate caspase-1. In particular, patients infected with P. aeruginosa develop diseases associated with high mortality, such as pneumonia, because no drug targets an ExoS or T3SS. We selected natural compounds to treat T3SS-mediated pneumonia and chose alizarin, a red dye. We confirmed the effects of alizarin on T3SS by bacterial PCR and ELISA. It was confirmed that alizarin regulates ExoS by inhibiting exsA but also popD and pscF. Furthermore, in infected H292 cells, it not only attenuates inflammation by inhibiting lipopolysaccharide (LPS)-induced phosphorylation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65 but also interferes with the level of ExoS delivered into the host and modulates caspase-1. We confirmed this result and determined that it led to decreases in proinflammatory cytokines such as Interleukin-1beta (IL-1β), Interleukin-6 (IL-6), and Interleukin-18 (IL-18). Therefore, we suggest that alizarin is a suitable drug for treating pneumonia caused by P. aeruginosa because it helps to attenuate inflammation by regulating T3SS and NF-κB signaling.

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  • Beyond pathogenicity: applications of the type III secretion system (T3SS) of Pseudomonas aeruginosa
    Tianqi Su, Lin Zhang, Jie Shen, Danyu Qian, Yulei Guo, Zhenpeng Li
    Frontiers in Microbiology.2025;[Epub]     CrossRef
Protocol
Protocol for the generation and purification of minicells from Lactiplantibacillus plantarum
Hyemin Kang, Donghyun Kim, Juhyun Kim
J. Microbiol. 2025;63(5):e2412002.   Published online April 30, 2025
DOI: https://doi.org/10.71150/jm.2412002
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AbstractAbstract PDF

Minicells, which are anucleate cells generated by irregular cell division, are emerging as promising drug delivery systems owing to advances in synthetic biology. However, their development is largely limited to a few model bacteria, highlighting the need to explore minicell platforms in alternative hosts. Lactiplantibacillus plantarum (L. plantarum), a probiotic bacterium classified as Generally Recognized as Safe, is an ideal candidate for such exploration. Minicell-producing L. plantarum was engineered by deleting the putative minD gene via plasmid-mediated homologous recombination, which inactivates cell division to form spherical minicells. Anucleate cells were isolated through differential centrifugation and filtration, followed by additional drug treatment to completely eliminate progenitor cells. Microscopy and flow cytometry analyses of the purified sample confirmed the absence of progenitor cells by DAPI staining. This protocol effectively produces bacterial minicells from L. plantarum for use in various biotechnological applications, including therapeutic agent delivery.

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  • A Safe and Versatile Minicell Platform Derived from Lactiplantibacillus plantarum for Biotechnological Applications
    Junhyeon Park, Seungjune Chang, Heymin Kang, SangKu Yi, In-Hwan Jang, Kyung-Ah Lee, Donghyun Kim, Juhyun Kim
    Journal of Microbiology and Biotechnology.2025;[Epub]     CrossRef
Full articles
Genomic profiling of soil nitrifying microorganisms enriched on floating membrane filter
Christiana Abiola, Joo-Han Gwak, Ui-Ju Lee, Aderonke Odunayo Adigun, Sung-Keun Rhee
J. Microbiol. 2025;63(4):e2502002.   Published online April 29, 2025
DOI: https://doi.org/10.71150/jm.2502002
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Recently, floating membrane filter cultivation was adopted to simulate solid surface and enrich surface-adapted soil ammonia-oxidizing archaea (AOA) communities from agricultural soil, as opposed to the conventional liquid medium. Here, we conducted metagenomic sequencing to recover nitrifier bins from the floating membrane filter cultures and reveal their genomic properties. Phylogenomic analysis showed that AOA bins recovered from this study, designated FF_bin01 and FF_bin02, are affiliated with the Nitrososphaeraceae family, while the third bin, FF_bin03, is a nitrite-oxidizing bacterium affiliated with the Nitrospiraceae family. Based on the ANI/AAI analysis, FF_bin01 and FF_bin02 are identified as novel species within the genera “Candidatus Nitrosocosmicus” and Nitrososphaera, respectively, while FF_bin03 represents a novel species within the genus Nitrospira. The pan and core genome analysis for the 29 AOA genomes considered in this study revealed 5,784 orthologous clusters, out of which 653 were core orthologous clusters. Additionally, 90 unique orthologous clusters were conserved among the Nitrososphaeraceae family, suggesting their potential role in enhancing culturability and adaptation to diverse environmental conditions. Intriguingly, FF_bin01 and FF_bin02 harbor a gene encoding manganese catalase and FF_bin03 also possesses a heme catalase gene, which might enhance their growth on the floating membrane filter. Overall, the floating membrane filter cultivation has proven to be a promising approach for isolating distinct soil AOA, and further modifications to this technique could stimulate the growth of a broader range of uncultivated nitrifiers from diverse soil environments.

Genetic insights into novel lysis suppression by phage CSP1 in Escherichia coli
Moosung Kim, Sangryeol Ryu
J. Microbiol. 2025;63(4):e2501013.   Published online April 29, 2025
DOI: https://doi.org/10.71150/jm.2501013
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AbstractAbstract PDFSupplementary Material

Lysis inhibition (LIN) in bacteriophage is a strategy to maximize progeny production. A clear plaque-forming mutant, CSP1C, was isolated from the turbid plaque-forming CSP1 phage. CSP1C exhibited an adsorption rate and replication dynamics similar to CSP1. Approximately 90% of the phages were adsorbed to the host cell within 12 min, and both phages had a latent period of 25 min. Burst sizes were 171.42 ± 31.75 plaque-forming units (PFU) per infected cell for CSP1 and 168.94 ± 51.67 PFU per infected cell for CSP1C. Both phages caused comparable reductions in viable E. coli cell counts at a low multiplicity of infection (MOI). However, CSP1 infection did not reduce turbidity, suggesting a form of LIN distinct from the well-characterized LIN of T4 phage. Genomic analysis revealed that a 4,672-base pairs (bp) DNA region, encompassing part of the tail fiber gene, CSP1_020, along with three hypothetical genes, CSP1_021, CSP1_022, and part of CSP1_023, was deleted from CSP1 to make CSP1C. Complementation analysis in CSP1C identified CSP1_020, CSP1_021, and CSP1_022 as a minimal gene set required for the lysis suppression in CSP1. Co-expression of these genes in E. coli with holin (CSP1_092) and endolysin (CSP1_091) resulted in lysis suppression. Lysis suppression was abolished by disrupting the proton motive force (PMF), supporting their potential role as antiholin. Additionally, CSP1_021 directly interacts with holin, suggesting that it may function as an antiholin. These findings identify new genetic factors involved in lysis suppression in CSP1, providing broader insights into phage strategies for modulating host cell lysis.

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  • Characterization and genome analyses of the novel phages targeting extraintestinal Escherichia coli clones ST131 and ST410
    Md Shamsuzzaman, Yoon-Jung Choi, Shukho Kim, Jungmin Kim
    International Microbiology.2025; 28(7): 2233.     CrossRef
Arctic lichen Cladonia borealis-induced cell death is mediated by p53-independent activation of Caspase-9 and PARP-1 signaling in human colorectal cancer cell lines
Ju-Mi Hong, Seul Ki Min, Kyung Hee Kim, Se Jong Han, Joung Han Yim, Sojin Kim, Youn-Jung Kim, Il-Chan Kim
J. Microbiol. 2025;63(4):e2412012.   Published online April 29, 2025
DOI: https://doi.org/10.71150/jm.2412012
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The anti-cancer effects of Cladonia borealis (an Arctic lichen) methanol extract (CBME) on human colon carcinoma HCT116 cells were investigated for the first time. The proliferation of the HCT116 cells treated with CBME significantly decreased in a dose- and time-dependent manner. Flow cytometry results indicated that treatment with CBME resulted in significant apoptosis in the HCT116 cells. Furthermore, immunoblotting and qRT-PCR results revealed the expression of apoptosis-related marker genes and indicated a significant downregulation of the apoptosis regulator B-cell lymphoma expression and upregulation of the cleaved form of poly (ADP-ribose) polymerase as DNA repair and apoptosis regulators and central tumor suppressor p53. Therefore, CBME significantly inhibited cell proliferation by inducing apoptosis via the mitochondrial apoptotic pathway in colon carcinoma cells. Collectively, these data suggested that CBME contained one or more compounds with anti-cancer effects and could be a potential therapeutic agent. Further studies are required to identify candidate compounds and understand the mechanism of action of CBME.

Whole-genome characterization and global phylogenetic comparison of cefotaxime-resistant Escherichia coli isolated from broiler chickens
Shahana Ahmed, Tridip Das, Chandan Nath, Tahia Ahmed, Keya Ghosh, Pangkaj Kumar Dhar, Ana Herrero-Fresno, Himel Barua, Paritosh Kumar Biswas, Md Zohorul Islam, John Elmerdahl Olsen
J. Microbiol. 2025;63(4):e2412009.   Published online April 29, 2025
DOI: https://doi.org/10.71150/jm.2412009
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AbstractAbstract PDFSupplementary Material

Antimicrobial resistance (AMR) poses a serious threat to public health, with the emergence of extended-spectrum beta-lactamases (ESBLs) in Enterobacteriaceae, particularly Escherichia coli, raising significant concerns. This study aims to elucidate the drivers of antimicrobial resistance, and the global spread of cefotaxime-resistant E. coli (CREC) strains. Whole-genome sequencing (WGS) was performed to explore genome-level characteristics, and phylogenetic analysis was conducted to compare twenty CREC strains from this study, which were isolated from broiler chicken farms in Bangladesh, with a global collection (n = 456) of CREC strains from multiple countries and hosts. The MIC analysis showed over 70% of strains isolated from broiler chickens exhibiting MIC values ≥ 256 mg/L for cefotaxime. Notably, 85% of the studied farms (17/20) tested positive for CREC by the end of the production cycle, with CREC counts increasing from 0.83 ± 1.75 log10 CFU/g feces on day 1 to 5.24 ± 0.72 log10 CFU/g feces by day 28. WGS revealed the presence of multiple resistance genes, including blaCTX-M, which was found in 30% of the strains. Phylogenetic comparison showed that the Bangladeshi strains were closely related to strains from diverse geographical regions and host species. This study provides a comprehensive understanding of the molecular epidemiology of CREC. The close phylogenetic relationships between Bangladeshi and global strains demonstrate the widespread presence of cefotaxime-resistant bacteria and emphasize the importance of monitoring AMR in food-producing animals to mitigate the spread of resistant strains.

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  • ESBL-Producing E. coli in Captive Black Bears: Molecular Characteristics and Risk of Dissemination
    Xin Lei, Mengjie Che, Yuxin Zhou, Shulei Pan, Xue Yang, Siyu Liu, Iram Laghari, Mingyue Wu, Ruilin Han, Xiaoqi Li, Lei Zhou, Guangneng Peng, Haifeng Liu, Ziyao Zhou, Kun Zhang, Zhijun Zhong
    Veterinary Sciences.2025; 12(11): 1085.     CrossRef

Journal of Microbiology : Journal of Microbiology
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