Journal of Microbiology

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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

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Abstract PDF Supplementary Material: Strains Mo2-6^T, S9, KG4-3^T, and 50Mo3-2, identified as coagulase-negative, Gram-stain-positive, halotolerant, non-motile coccoid bacteria, were isolated from traditional Korean soybean foods. Strains Mo2-6^T and S9 were both catalase- and oxidase-negative, whereas KG4-3^T and 50Mo3-2 were catalase-positive but oxidase-negative. The optimal growth conditions for Mo2-6^T and S9 were 30°C, 2% NaCl, and pH 7.0, while KG4-3^T 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-C_15:0 and iso-C_15:0 as the major cellular fatty acids (> 10%). Additionally, anteiso-C_13:0 was a major fatty acid in strain KG4-3^T. The DNA G + C contents of strains Mo2-6^T, S9, KG4-3^T, 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 Mo2-6^T and S9, as well as KG4-3^T and 50Mo3-2, formed distinct lineages within the genus Staphylococcus. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) analyses confirmed that strains Mo2-6^T and S9, as well as KG4-3^T and 50Mo3-2, belonged to the same species. Meanwhile, dDDH and ANI values between strains Mo2-6^T and KG4-3^T, 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 Mo2-6^T as the type strain of Staphylococcus parequorum sp. nov. (=KACC 23685^T =JCM 37038^T) and strain KG4-3^T as the type strain of Staphylococcus halotolerans sp. nov. (=KACC 23684^T =JCM 37037^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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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

Review

Small regulatory RNAs as key modulators of antibiotic resistance in pathogenic bacteria: Yubin Yang, Hana Hyeon, Minju Joo, Kangseok Lee, Eunkyoung Shin; J. Microbiol. 2025;63(4):e2501027. Published online April 2, 2025; DOI: https://doi.org/10.71150/jm.2501027

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