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

I. J. Carrasco¹, M. C. Márquez¹, X. Yanfen², Y. Ma², D. A. Cowan³, B. E. Jones⁴, W. D. Grant⁵ and A. Ventosa¹

Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Sevilla, 41012 Sevilla, Spain

Three Gram-positive, moderately halophilic, spore-forming rods, designated XH-63^T, 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 had meso-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-63^T, selected as the representative strain, consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and a phospholipid and two amino phospholipids of unknown structure. This strain possessed anteiso-C_{15 : 0}and anteiso-C_{17 : 0} as 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 the Gracilibacillus cluster, with highest sequence similarity (95·4-95·8 %) with Gracilibacillus dipsosauri. Based on a combination of phenotypic, chemotaxonomic and phylogenetic features, it is proposed that the three isolates represent a novel species of the genus Gracilibacillus, Gracilibacillus orientalis sp. nov. The type strain is strain XH-63^T (=CCM 7326^T=AS 1.4250^T=CEC^T 7097^T).

Keywords: Gracilibacillus orientalis, halophilic bacterium, Gracilibacillus, phosphatidylglycerol, microorganisms,Taxonomy, Microbes.

E-mail: ventosa@us.es