干旱区生态环境知识资源中心

The taxonomic positions of two gamma- and UV-ray-resistant strains isolated from radiation-polluted soil in north-west China were determined in a polyphasic study. The organisms, designated R12(T) and R13(T), were Gram-stain-positive, non-spore-forming cocci, which contained MK-8 as the major respiratory quinone and C(16:1)omega 7c and C(16:0) as major fatty acids. The cell walls of strains R12(T) and R13(T) contained ornithine. Phylogenetic analysis based on 16S rRNA gene sequences and DNA DNA hybridizations showed that strains R12(T) and R13(T) are members of novel species belonging to the genus Deinococcus, with Deinococcus radiodurans DSM 20539(T) as the closest relative. The isolates R12(T) and R13(T) shared 97 and 97.1 % 16S rRNA gene similarity, respectively, and 29.5 and 33.3% DNA DNA relatedness, respectively, with D. radiodurans DSM 20539(T). The DNA G + C contents of isolates R12(T) and R13(T) were 66.7 and 63.8%, respectively. On the basis of phenotypic tests and other results, two species, Deinococcus wulumuqiensis sp. nov. (type strain R12(T) =CGMCC 1.8884(T) =NBRC 105665(T)) and Deinococcus xibeiensis sp. nov. (type strain R13(T) =CGMCC 1.8885(T) =NBRC 105666(T)), are proposed.