Marinimicrobium koreense gen. nov., sp nov and Marinimicrobium agarilyticum sp nov., novel moderately halotolerant bacteria isolated from tidal flat sediment in Korea

Abstract

Two moderately halotolerant Gram-negative bacteria were isolated from tidal flat sediment of the South Sea in Korea (the Korea Strait). The strains, designated M9(T) and M18(T), were strictly aerobic, rod-shaped and non-spore-forming and motile with a flagellum and their major fatty acids were C-16:0 and C-19:0 cyclo omega 8c. Strains Mg-T and M18(T) could grow in the presence of up to 13-15% (w/v) NaCl, but their optimum salt concentrations were relatively low (0-3 %, w/v). The major predominant isoprenoid quinone was Q-8 and the G+C content of the genomic DNA was 57-58 mol%. Phylogenetic analyses and comparative 16S rRNA gene sequence studies revealed that strains M9(T) and M18(T) formed a phylogenetic lineage distinct from the genus Teredinibacter within the class Gammaproteobacteria and were most closely related to the genera Microbulbifer, Saccharophagus and Teredinibacter, with less than 92.5% 16S rRNA gene sequence similarity. The level of 16S rRNA gene sequence similarity between the two strains was 96-7 %. On the basis of physiological and phylogenetic properties, strains M9(T) and M18(T) represent separate species within a novel genus of the class Gammaproteobacteria, for which the names Marinimicrobium koreense gen. nov., sp. nov. (type species) and Marinimicrobium agarilyticum sp. nov. are proposed. The type strains of Marinimicrobium koreense and Marinimicrobium agarilyticum are M9(T) (=KCTC 12356(T)=DSM 16974(T)) and M18(T) (=KCTC 12357(T)=DSM 16975(T)), respectively.