Characterization of Flavobacterium aquimarinum sp. nov., a halotolerant bacterium isolated from seawater

A novel, aerobic, Gram-stain-negative, non-motile, non-spore forming, rod-shaped bacterium, designated strain Dol 15-39^T, was isolated from a seawater sample near Geoje Island in the South Sea, Republic of Korea. The strain was found to be oxidase-negative and catalase-positive. The isolate was observed to grow at temperatures from 4 to 37°C, at salinities of up to 7%, and at pH levels from 6 to 9; moreover, it was not able to degrade starch, DNA, esculin, or tyrosine. Phylogenetic analysis based on 16S rRNA gene sequences showed that Dol 15-39^T was most closely related to Flavobacterium jumunjinense HME7102^T with a sequence similarity of 97.3%. However, the levels of DNA-DNA relatedness between Dol 15-39^T and the most closely related species were much lower than 70%, confirming that they represented distinct genomic species. The genomic DNA G + C content of Dol 15-39^T was calculated to be 32.6 mol%. MK-6 was the predominant respiratory quinine, while iso-C_15:0 (25.0%), iso-C_15:1 G (17.0%), and iso-C_17:0 3-OH (10.4%) were the major cellular fatty acids. Phosphatidylethanolamine was identified as a major polar lipid, while various unidentified aminolipids and polar lipids were also detected. Based on polyphasic taxonomic data, Dol 15-39^T represents a novel species of the genus Flavobacterium, for which the name F. aquimarinum sp. nov. is proposed. The type strain is accessible under the culture collection numbers (KEMB 9005-617^T = JCM 31930^T).