AUTHOR=Kim Bora , Yang Ah-In , Joe Hae-In , Kim Ki Hyun , Choe Hanna , Joe Sung-Hong , Jun Min Ok , Shin Na-Ri 

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

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1303039

DOI=10.3389/fmicb.2023.1303039

ISSN=1664-302X

ABSTRACT=<p>Halophilic bacterial strains, designated SG2L-4<sup>T</sup>, 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<sup>T</sup> is closely related to <italic>Halomonas garicola</italic> KACC 18117<sup>T</sup> with a similarity of 96.2%. The complete genome sequence of strain SG2L-4<sup>T</sup> 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<sup>T</sup> and <italic>H. garicola</italic> KACC 18117<sup>T</sup> were 90.5 and 40.7%, respectively. The optimal growth conditions for strain SG2L-4<sup>T</sup> 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<sub>16:0</sub>, summed features 8 (C<sub>18:1</sub><italic>ω</italic>6<italic>c</italic> and/or C<sub>18:1</sub><italic>ω</italic>7<italic>c</italic>), C<sub>19:0</sub> cyclo <italic>ω</italic>8<italic>c</italic>, and summed features 3 (C<sub>16:1</sub><italic>ω</italic>6<italic>c</italic> and/or C<sub>16:1</sub><italic>ω</italic>7<italic>c</italic>). The predominant respiratory quinone was ubiquinone with nine isoprene units (Q-9). Based on the phenotypic, genotypic, and chemotaxonomic results, strain SG2L-4<sup>T</sup> represents a novel species within the genus <italic>Halomonas</italic>, for which the name <italic>Halomonas piscis</italic> sp. nov. is proposed. The type strain is SG2L-4<sup>T</sup> (=KCTC 92842<sup>T</sup> = JCM 35929<sup>T</sup>). Functional annotation of the genome of strain SG2L-4<sup>T</sup> confirmed the presence of exopolysaccharide synthesis protein (ExoD) and capsular polysaccharide-related genes. Strain SG2L-4<sup>T</sup> 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 <italic>H. piscis</italic> sp. nov. isolated from jeotgal, contributing to understanding its potential roles in food and biotechnological applications.</p>