Shewanella phaeophyticola sp. nov. and Vibrio algarum sp. nov., isolated from marine brown algae

Two Gram-stain-negative, rod-shaped bacteria, designated as strains KJ10-1 T and KJ40-1 T , were isolated from marine brown algae. Both strains were catalase-positive, oxidase-positive, and facultative aerobic. Strain KJ10-1 T exhibited optimal growth at 25 °C, pH 7.0, and 3 % NaCl, whereas strain KJ40-1 T showed optimal growth at 25 °C, pH 7.0, and 2 % NaCl. The respiratory quinones of strain KJ10-1 T were ubiquinone-8, ubiquinone-7, menaquinone-7, and methylated menaquinone-7, while the respiratory quinone of strain KJ40-1 T was only ubiquinone-8. As major fatty acids, strain KJ10-1 T contained C 16 : 0 , C 17 : 1 ω8 c , iso-C 15 : 0 , and summed feature 3 (C 16 : 1 ω 7 c and/or C 16 : 1 ω 6 c ) and strain KJ40-1 T contained C 16 : 0 and summed features 3 and 8 (C 18 : 1 ω 7 c and/or C 18 : 1 ω 6 c ). The major polar lipids in strain KJ10-1 T were phosphatidylethanolamine, phosphatidylglycerol, and an unidentified aminolipid, whereas those in strain KJ40-1 T were phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol. The DNA G+C contents of strains KJ10-1 T and KJ40-1 T were 42.1 and 40.8 mol%, respectively. Based on 16S rRNA gene sequences, strains KJ10-1 T and KJ40-1 T exhibited the closest relatedness to Shewanella saliphila MMS16-UL250 T (98.6 %) and Vibrio rumoiensis S-1 T (95.4 %), respectively. Phylogenetic analyses, based on both 16S rRNA and 92 housekeeping genes, showed that the strains formed distinct phylogenic lineages within the genera Shewanella and Vibrio . Digital DNA–DNA hybridization and orthologous average nucleotide identity values between strain KJ10-1 T and other Shewanella species, as well as between strain KJ40-1 T and other Vibrio species, were below the thresholds commonly accepted for prokaryotic species delineation. Based on the phenotypic, chemotaxonomic, and phylogenetic data, strains KJ10-1 T and KJ40-1 T represent novel species of the genera Shewanella and Vibrio , respectively, for which the names Shewanella phaeophyticola sp. nov. and Vibrio algarum sp. nov. are proposed, respectively. The type strains of S. phaeophyticola and V. algarum are KJ10-1 T (=KACC 22589 T =JCM 35409 T ) and KJ40-1 T (=KACC 22588 T =JCM 35410 T ), respectively.