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

Two moderately halotolerant Gram-negative bacteria were isolated from tidal flat sediment of the South Sea in Korea (the Korea Strait). The strains, designated M9T and M18T, 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 omega8c. Strains M9T and M18T 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 M9T and M18T 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 M9T and M18T 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 M9T (= KCTC 12356T = DSM 16974T) and M18T (= KCTC 12357T = DSM 16975T), respectively.