Gracilibacillus orientalis sp. nov., a novel moderately halophilic bacterium isolated from a salt lake in Inner Mongolia, China

Abstract

Three Gram-positive, moderately halophilic, spore-forming rods, designated XH-63T, XH-62 and EJ-15, were isolated from two salt lakes located near Xilin Hot and Ejinor, in Inner Mongolia, China. The strains were strictly aerobic and motile, with spherical, terminal and deforming endospores. They grew at pH 5·0–9·0 (optimal growth at pH 7·5), between 4 and 45 °C (optimal growth at 37 °C) and at salinities of 1–20 % (w/v) total salts, growing optimally at 10 % (w/v) salts. They hadmeso-diaminopimelic acid in the cell wall peptidoglycan and DNA G+C contents of 36·1–37·1 mol%. The polar lipid pattern of strain XH-63T, selected as the representative strain, consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and a phospholipid and two amino phospholipids of unknown structure. This strain possessed anteiso-C15 : 0and anteiso-C17 : 0as the major fatty acids (altogether representing 72·5 % of total) and MK-7 as the major menaquinone. 16S rRNA gene analysis of the three strains showed that they were within theGracilibacilluscluster, with highest sequence similarity (95·4–95·8 %) withGracilibacillus dipsosauri. Based on a combination of phenotypic, chemotaxonomic and phylogenetic features, it is proposed that the three isolates represent a novel species of the genusGracilibacillus,Gracilibacillus orientalissp. nov. The type strain is strain XH-63T(=CCM 7326T=AS 1.4250T=CECT 7097T).