Psychroflexus sediminis sp. nov., a mesophilic bacterium isolated from salt lake sediment in China.

A novel Gram-negative, mesophilic, slightly halophilic, catalase- and oxidase-positive, obligately aerobic bacterium, designated strain YIM-C238(T), was isolated from a sediment sample from a salt lake in the Qaidam Basin, north-west China. Cells were non-sporulating, non-motile, straight to slightly curved rods. Coccoid bodies and filaments of varying length developed in older cultures. Growth occurred with 0.5-6 % (w/v) NaCl [optimum, 2-3 % (w/v) NaCl], at pH 6.0-10.0 (optimum, pH 7.0-8.0) and at 10-40 degrees C (optimum, 25-30 degrees C). The major cellular fatty acids were anteiso-C(15 : 0), 3-OH iso-C(16 : 0) and anteiso-C(15 : 1)omega10c, and menaquinone 6 was the sole respiratory quinone. Non-diffusible carotenoid pigments were produced. Flexirubin pigments were absent. The genomic DNA G+C content was 35.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YIM-C238(T) should be assigned to the genus Psychroflexus. The sequence similarities between the isolate and the type strains of members of the genus Psychroflexus were in the range 95.5-97.0 %. The combination of phylogenetic analysis, DNA-DNA hybridization data, phenotypic characteristics and chemotaxonomic differences supported the view that strain YIM-C238(T) represents a novel species of the genus Psychroflexus, for which the name Psychroflexus sediminis sp. nov. is proposed. The type strain is YIM-C238(T) (=CCTCC AA 207030(T)=KCTC 22166(T)).