Journal of Microbiology

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Mucilaginibacter florum sp. nov., isolated from the flower of Coreopsis grandiflora and Mucilaginibacter oryzagri sp. nov., isolated from rice paddy soil in Korea: Parthiban Subramanian, Jun Heo, Daseul Lee, Seunghwan Kim, Hyorim Choi, Yunhee Choi, Yiseul Kim; J. Microbiol. 2025;63(12):e2509014. Published online December 31, 2025; DOI: https://doi.org/10.71150/jm.2509014

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Abstract PDF Supplementary Material: Two aerobic, Gram-stain-negative, non-motile and rod-shaped bacterial strains designated GGG-R5^T and M4-18^T were isolated from flowers of golden wave (Coreopsis grandiflora) and rice paddy soil, respectively in the Republic of Korea. Both strains were pigmented and produced flexirubin-type pigments. Based on phylogenetic analysis using 16S rRNA gene sequence, both strains were placed within the genus Mucilaginibacter with M. agri R11^T and M. jinjuensis YC7004^T both being the closest relatives to GGG-R5^T (97.7%) and in case of M4-18^T, M. ginsenosidivorax KHI28^T (98.5%) was the nearest neighbor. Characteristic to genus Mucilaginibacter, the major cellular fatty acids in both strains were iso-C_15:0, iso-C_{17:0 3-OH}, summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c); menaquinone-7 was the major menaquinone and phosphatidylethanolamine was the major polar lipid observed. Comparison of genome sequences with the other members of Mucilaginibacter indicated orthologous average nucleotide identity (orthoANI) at 73.3–73.5% for GGG-R5^T and 78.9–88.5% for M4-18^T. Digital DNA-DNA hybridization (dDDH) values ranged at 19.1–19.7% between GGG-R5^T and its neighbor species. In case of M4-18^T, the observed range was at 21.9–36.6%. Considering the 16S rRNA similarity, orthoANI and dDDH values as well as comparison of phenotypic and chemotaxonomic characteristics indicated that both strains belonged to genus Mucilaginibacter but were distinctly distinguishable from previously described species. The strains GGG-R5^T and M4-18^T, therefore represent distinct novel species for which names Mucilaginibacter florum GGG-R5^T and Mucilaginibacter oryzagri M4-18^T are proposed. The type strains are GGG-R5^T (= KACC 22063^T = JCM 36590^T) and M4-18^T (= KACC 22773^T = JCM 35894^T).

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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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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Revolutionizing seafood safety with bacteriophages: emerging technologies and applications
Nigar Sultana Meghla, Soo-Jin Jung, Md Furkanur Rahaman Mizan, Syeda Roufun Nesa, IkSoon Kang, Sang-Do Ha
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Synthetic biology strategies for sustainable bioplastic production by yeasts: Huong-Giang Le, Yongjae Lee, Sun-Mi Lee; J. Microbiol. 2025;63(3):e2501022. Published online March 28, 2025; DOI: https://doi.org/10.71150/jm.2501022

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