Gracilibacillus quinghaiensis sp. nov., isolated from salt-lake sediment in the Qaidam Basin, north-west China.

Abstract: A motile, Gram-positive, slightly halophilic, endospore-forming, catalase- and oxidase-positive, obligately aerobic, slender rod-shaped bacterium, strain YIM-C229^T was isolated from the sediment of a salt lake in the Qaidam Basin, north-west China. Filamentous forms were present throughout the growth cycle. Strain YIM-C229^T grew in the presence of 0.5–8% NaCl and at pH 6.0–8.5, with optimum growth at 1–3% NaCl and pH 7.0–7.5. It grew at 4–45°C, with optimum growth at 37°C. The major cellular fatty acids were anteiso-C_15:0, C_16:0, iso-C_15:0, C_16:1 ω11c and anteiso-C_17:0. The predominant respiratory quinone was MK-7, and diphosphatidylglycerol and phosphatidylglycerol were the polar lipids, with meso-diaminopimelic acid occurring in the cell-wall peptidoglycan. The genomic DNA G+C content was 40.9mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YIM-C229^T was closely related to the type strains of the four recognized species of the genus Gracilibacillus: G. halotolerans NN^T (sequence similarity 95.5%), G. dipsosauri DD1^T (96.1%), G. orientalis XH-63^T (96.8%) and G. boraciitolerans T-16X^T (99.1%). The DNA–DNA relatedness between strain YIM-C229^T and G. boraciitolerans DSM 17256^T was 30.8%. The combination of phylogenetic analysis, phenotypic characteristics, chemotaxonomic differences and DNA–DNA hybridization data supported the view that this strain represented a novel species of the genus Gracilibacillus, for which the name Gracilibacillus quinghaiensis sp. nov. is proposed, with YIM-C229^T (=DSM 17858^T=CGMCC 1.6304^T) as the type strain. [Copyright &y& Elsevier]