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

摘要

A motile, Gram-positive, slightly halophilic, endospore-forming, catalase- and oxidase-positive, obligately aerobic, slender rod-shaped bacterium, strain YIM-C229 super(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 super(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 super(o)C, with optimum growth at 37 super(o)C. The major cellular fatty acids were anteiso-C sub(1) sub(5) sub(:) sub(0), C sub(1) sub(6) sub(:) sub(0), iso-C sub(1) sub(5) sub(:) sub(0), C sub(1) sub(6) sub(:) sub(1) omega 11c and anteiso-C sub(1) sub(7) sub(:) sub(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 super(T) was closely related to the type strains of the four recognized species of the genus Gracilibacillus: G. halotolerans NN super(T) (sequence similarity 95.5%), G. dipsosauri DD1 super(T) (96.1%), G. orientalis XH-63 super(T) (96.8%) and G. boraciitolerans T-16X super(T) (99.1%). The DNA-DNA relatedness between strain YIM-C229 super(T) and G. boraciitolerans DSM 17256 super(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 super(T) (=DSM 17858 super(T)=CGMCC 1.6304 super(T)) as the type strain.