Genomic attributes and characterization of novel exopolysaccharide-producing bacterium Halomonas piscis sp. nov. isolated from jeotgal.

Halophilic bacterial strains, designated SG2L-4^T, SB1M4, and SB2L-5, were isolated from jeotgal, a traditional Korean fermented food. Cells are Gram-stain-negative, aerobic, non-motile, rod-shaped, catalase-positive, and oxidase-negative. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain SG2L-4^T is closely related to Halomonas garicola KACC 18117^T with a similarity of 96.2%. The complete genome sequence of strain SG2L-4^T was 3,227,066  bp in size, with a genomic G  +  C content of 63.3  mol%. The average nucleotide identity and digital DNA–DNA hybridization values between strain SG2L-4^T and H. garicola KACC 18117^T were 90.5 and 40.7%, respectively. The optimal growth conditions for strain SG2L-4^T were temperatures between 30 and 37°C, a pH value of 7, and the presence of 10% (w/v) NaCl. The polar lipids identified included diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unknown phospholipid, an unknown glycolipid, and an unknown polar lipid. The major cellular fatty acids were C_16:0, summed features 8 (C_18:1 ω6c and/or C_18:1 ω7c), C_19:0 cyclo ω8c, and summed features 3 (C_16:1 ω6c and/or C_16:1 ω7c). The predominant respiratory quinone was ubiquinone with nine isoprene units (Q-9). Based on the phenotypic, genotypic, and chemotaxonomic results, strain SG2L-4^T represents a novel species within the genus Halomonas, for which the name Halomonas piscis sp. nov. is proposed. The type strain is SG2L-4^T (=KCTC 92842^T   =  JCM 35929^T ). Functional annotation of the genome of strain SG2L4^T confirmed the presence of exopolysaccharide synthesis protein (ExoD) and capsular polysaccharide-related genes. Strain SG2L-4^T also exhibited positive results in Molisch’s test, indicating the presence of extracellular carbohydrates and exopolysaccharides (EPS) production. These findings provide valuable insights into the EPS-producing capabilities of H. piscis sp. nov. isolated from jeotgal, contributing to understanding its potential roles in food and biotechnological applications. [ABSTRACT FROM AUTHOR]