Microbulbifer discodermiae sp. nov. and Microbulbifer jejuensis sp. nov., isolated from marine sponges

Two Gram-stain-negative, facultatively anaerobic, non-motile and rod-shaped bacterial strains, designated 2201CG32-9 T and 2304DJ12-6 T , were isolated from marine sponges collected in the Republic of Korea. Both strains exhibited catalase and oxidase activities but tested negative for nitrate reduction and indole production. Strain 2201CG32-9 T showed optimal growth at 30 °C and pH 7.0–8.0 in the presence of 3% (w/v) NaCl, whereas strain 2304DJ12-6 T grew optimally at 25 °C, pH 8.0 and 3% (w/v) NaCl. Phylogenetic analysis of the 16S rRNA gene and phylogenomic analysis of genome sequences indicated that strains 2201CG32-9 T and 2304DJ12-6 T represented novel species within the genus Microbulbifer . Based on whole-genome phylogenomic analysis, the two strains were most closely related to Microbulbifer okhotskensis OS29 T and Microbulbifer variabilis ATCC 700307 T , respectively. The average nucleotide identity values of these strains were found to be <75.9%, and their digital DNA–DNA hybridization values were <22.5%. The DNA G+C contents of strains 2201CG32-9 T and 2304DJ12-6 T were 56.5 and 53.5 mol%, respectively. In both strains, ubiquinone-8 was identified as the predominant respiratory quinone, and the major cellular fatty acids (>5.0%) were C 16:0 , iso-C 11:0 3-OH, iso-C 15:0 , iso-C 17:0 , summed feature 8 and summed feature 9. As for polar lipids, both strains comprised phosphatidylglycerol, phosphatidylethanolamine and phosphoglycolipid as common major polar lipids. Strains 2201CG32-9 T and 2304DJ12-6 T are classified as two novel species of the genus Microbulbifer based on a polyphasic taxonomic approach, for which the names Microbulbifer discodermiae sp. nov. (2201CG32-9 T =KACC 23829 T =JCM 37223 T ) and Microbulbifer jejuensis sp. nov. (2304DJ12-6 T =KACC 23832 T =MCCC 1K09533 T ) are proposed, respectively.