Journal of Microbiology

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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Abstract PDF Supplementary 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 phoU^A147E 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 phoU^A147E 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.

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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Abstract 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.

Research Articles

Enoxacin adversely affects Salmonella enterica virulence and host pathogenesis through interference with type III secretion system type II (T3SS-II) and disruption of translocation of Salmonella Pathogenicity Island-2 (SPI2) effectors: El-Sayed Khafagy, Gamal A. Soliman, Maged S. Abdel-Kader, Mahmoud M. Bendary, Wael A. H. Hegazy, Momen Askoura; J. Microbiol. 2025;63(2):e2410015. Published online February 27, 2025; DOI: https://doi.org/10.71150/jm.2410015

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Abstract PDF: Salmonella enterica is a clinically significant oro-fecal pathogen that causes a wide variety of illnesses and can lead to epidemics. S. enterica expresses a lot of virulence factors that enhance its pathogenesis in host. For instance, S. enterica employs a type three secretion system (T3SS) to translocate a wide array of effector proteins that could change the surrounding niche ensuring suitable conditions for the thrive of Salmonella infection. Many antimicrobials have been recently introduced to overcome the annoying bacterial resistance to antibiotics. Enoxacin is member of the second-generation quinolones that possesses a considerable activity against S. enterica. The present study aimed to evaluate the effect of enoxacin at sub-minimum inhibitory concentration (sub-MIC) on S. enterica virulence capability and pathogenesis in host. Enoxacin at sub-MIC significantly diminished both Salmonella invasion and intracellular replication within the host cells. The observed inhibitory effect of enoxacin on S. enterica internalization could be attributed to its ability to interfere with translocation of the T3SS effector proteins. These results were further confirmed by the finding that enoxacin at sub-MIC down-regulated the expression of the genes encoding for T3SS-type II (T3SS-II). Moreover, enoxacin at sub-MIC lessened bacterial adhesion to abiotic surface and biofilm formation which indicates a potential anti-virulence activity. Importantly, in vivo results showed a significant ability of enoxacin to protect mice against S. enterica infection and decreased bacterial colonization within animal tissues. In nutshell, current findings shed light on an additional mechanism of enoxacin at sub-MIC by interfering with Salmonella intracellular replication. The outcomes presented herein could be further invested in conquering bacterial resistance and open the door for additional effective clinical applications.

PneusPage: A WEB-BASED TOOL for the analysis of Whole-Genome Sequencing Data of Streptococcus pneumonia: Eunju Hong, Youngjin Shin, Hyunseong Kim, Woo Young Cho, Woo-Hyun Song, Seung-Hyun Jung, Minho Lee; J. Microbiol. 2025;63(1):e.2409020. Published online January 24, 2025; DOI: https://doi.org/10.71150/jm.2409020

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Abstract PDF Supplementary Material

With the advent of whole-genome sequencing, opportunities to investigate the population structure, transmission patterns, antimicrobial resistance profiles, and virulence determinants of Streptococcus pneumoniae at high resolution have been increasingly expanding. Consequently, a user-friendly bioinformatics tool is needed to automate the analysis of Streptococcus pneumoniae whole-genome sequencing data, summarize clinically relevant genomic features, and further guide treatment options. Here, we developed PneusPage, a web-based tool that integrates functions for species prediction, molecular typing, drug resistance determination, and data visualization of Streptococcus pneumoniae. To evaluate the performance of PneusPage, we analyzed 80 pneumococcal genomes with different serotypes from the Global Pneumococcal Sequencing Project and compared the results with those from another platform, PathogenWatch. We observed a high concordance between the two platforms in terms of serotypes (100% concordance rate), multilocus sequence typing (100% concordance rate), penicillin-binding protein typing (88.8% concordance rate), and the Global Pneumococcal Sequencing Clusters (98.8% concordance rate). In addition, PneusPage offers integrated analysis functions for the detection of virulence and mobile genetic elements that are not provided by previous platforms. By automating the analysis pipeline, PneusPage makes whole-genome sequencing data more accessible to non-specialist users, including microbiologists, epidemiologists, and clinicians, thereby enhancing the utility of whole-genome sequencing in both research and clinical settings. PneusPage is available at https://pneuspage.minholee.net/.

Citations

Citations to this article as recorded by

Genomic analysis and pneumococcal population dynamics across PCV implementation in South Korea, 1997–2023
Jeong-Ih Shin, Sung-Yeon Cho, Jiyon Chu, Chulmin Park, Minho Lee, Joon Young Song, Seung-Hyun Jung, Dong-Gun Lee
Microbial Genomics .2025;[Epub] CrossRef
GPS Pipeline: portable, scalable genomic pipeline for Streptococcus pneumoniae surveillance from Global Pneumococcal Sequencing Project
Harry C. H. Hung, Narender Kumar, Victoria Dyster, Corin Yeats, Benjamin Metcalf, Yuan Li, Paulina A. Hawkins, Lesley McGee, Stephen D. Bentley, Stephanie W. Lo
Nature Communications.2025;[Epub] CrossRef

Journal Articles

Hydroxychloroquine an Antimalarial Drug, Exhibits Potent Antifungal Efficacy Against Candida albicans Through Multitargeting: Sargun Tushar Basrani, Tanjila Chandsaheb Gavandi, Shivani Balasaheb Patil, Nandkumar Subhash Kadam, Dhairyasheel Vasantrao Yadav, Sayali Ashok Chougule, Sankunny Mohan Karuppayil, Ashwini Khanderao Jadhav; J. Microbiol. 2024;62(5):381-391. Published online April 8, 2024; DOI: https://doi.org/10.1007/s12275-024-00111-6

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