Brachybacterium aquaticum sp. nov., a novel actinobacterium isolated from seawater.

Abstract

A pale-yellowish bacterium, strain KWS-1T, was isolated from seawater during a study of the bacterial diversity of the marine environment of the Kanyakumari coastal region of the Bay of Bengal, India, and was studied by using a polyphasic taxonomic approach. Strain KWS-1T had morphological and chemotaxonomic properties (cell-wall diamino acid, menaquinone and fatty acid profile) consistent with its classification in the genus Brachybacterium. Phylogenetic analysis of the 16S rRNA gene sequence showed that strain KWS-1T was related most closely to Brachybacterium paraconglomeratum JCM 17781T, followed by Brachybacterium saurashtrense DSM 23186T, Brachybacterium gingengisoli JCM 19356T, Brachybacterium faecium JCM 11609T and Brachybacterium conglomeratum JCM 11608T (98.45, 98.24, 98.12, 98.10 and 98.10 % similarity, respectively), whereas the sequence similarity values with respect to the other Brachybacterium species with validly published names were between 97.4 and 94.2 %. However, the DNA-DNA hybridization values between strain KWS-1T and the five most closely related species were less than the threshold value for species discrimination. The major lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylserine and the major quinone was menaquinone MK-7. The DNA G+C content of strain KWS-1T was 71.8 mol%. The above data in combination with the phenotypic distinctiveness of strain KWS-1T from other reference strains clearly indicate that the strain represents a novel species, for which the name Brachybacterium aquaticum sp. nov. is proposed. The type strain is KWS-1T (=MTCC 11836T=DSM 28796T=JCM 30059T).