Deinococcus gobiensis sp. nov., an extremely radiation-resistant bacterium

Abstract

A Gram-positive, non-motile, spherical, red-pigmented and facultatively anaerobic bacterium, designated strain I-0 T , was isolated from a sand sample of the Gobi desert in Xinjiang Autonomous Region, China. Phylogenetic analysis based on 16S rRNA gene sequences indicated that this isolate represents a novel member of the genus Deinococcus, with low sequence similarities (,94 %) to recognized Deinococcus species. The major cellular fatty acids were C 16 : 1 v7c and C 16 : 0 . Its polar lipid profile contained several unidentified glycolipids, phosphoglycolipids, phospholipids, pigments and an aminophospholipid. The peptidoglycan type was Orn-Gly 2 (A3b) and the predominant respiratory quinone was MK-8. The DNA G+C content was 65.4 mol%. DNA-DNA relatedness between strain I-0 T and Deinococcus radiodurans ACCC 10492 T was 37 %. The strain was shown to be extremely resistant to gamma radiation (.15 kGy) and UV light (.600 J m "2 ). On the basis of the phylogenetic, chemotaxonomic and phenotypic data presented, strain I-0 T represents a novel species of the genus Deinococcus, for which the name Deinococcus gobiensis sp. nov. is proposed. The type strain is I-0 T (5DSM 21396 T 5CGMCC 1.7299 T ).The genus Deinococcus, which was described by Brooks & Murray (1981) ) and desiccation (years) is a distinctive characteristic of this genus (Makarova et al., 2007). This resistance has been attributed to a highly proficient DNA repair system, and it seems likely that radiation resistance evolved as a consequence of chronic exposure to non-radioactive forms of DNA damage, such as desiccation (Makarova et al., 2001).In the course of the study of stress-resistant bacteria from arid environments, a novel Deinococcus isolate was obtained from the upper sand layers of the Gobi desert, Xinjiang, China, where bacteria are exposed to cycles of high and low temperatures and to prolonged desiccation. In this paper, we report on the taxonomic characterization of this radiation-resistant, red-coloured strain, designated I-0 T , which was obtained from a mixed sand sample. After exposure of the sample to 10 kGy gamma radiation from a 60 Co source (CAIC), it was enriched in 50 ml TGY medium (1.0 % peptone, 0.5 % yeast extract, 0.1 % glucose) at 30 u C with shaking at 200 r.p.m. for up to 5 days, followed by isolation of surviving red-colony-forming bacteria on TGY agar plates (TGY medium with 1.5 % agar).Morphology of cells grown for 24-48 h on TGY agar was examined by zoom stereo microscopy (model SZX7; Olympus), light microscopy (model BX-51; Olympus), scanning electron microscopy (model S-570; Hitachi) and transmission electron microscopy (model H-7500; Hitachi). Gram staining was carried out using the modified 3These authors contributed equally to this work.The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain I-0 T is EU427464.Micrographs of colonies and cells of strain I-0 T , a 16S rRNA gene sequence-based maximum-parsimony tree, the fatty acid profile of strain I-0 T and a table of 16S rRNA gene sequence s...

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Community Variability of Bacteria in Alpine Snow (Mont Blanc) Containing Saharan Dust Deposition and Their Snow Colonisation Potential

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