Deinococcus radiotolerans sp. nov., a gamma-radiation-resistant bacterium isolated from gamma ray-irradiated soil

Two gamma-radiation-resistant bacterial strains, designated C1^T and C2, were isolated from a soil sample collected at Jeongeup-Si, South Korea. These strains were observed to be Gram-negative, non-motile, rod-shaped, and to form pink colonies. Phylogenetic analysis based on 16S rRNA gene sequences revealed that these strains belong to the genus Deinococcus in the family Deinococcaceae. Strains C1^T and C2 have the highest sequence similarities with Deinococcus daejeonensis MJ27^T (97.56 %) and Deinococcus grandis DSM 39663^T (97.50 %). Like other members of the genus Deinococcus, the novel isolates showed resistance to gamma-radiation with a D₁₀ value in excess of 8 kGy. The isolates were found to have menaquinone MK-8 as the predominant respiratory quinone and an unidentified phosphoglycolipid as major polar lipid. In addition, the most abundant fatty acids of strain C1^T were identified as C_15:1 ω6c (25.5 %), C_16:1 ω7c (18.7 %) and C_15:0 (9.7 %). Genomic analysis results showed that the DNA G+C contents of strain C1^T and C2 are 68.59 and 68.57 %, respectively. Taken together, the polyphasic taxonomic data support the proposal that the isolates C1^T and C2 represent a novel species of the genus Deinococcus, for which the name Deinococcus radiotolerans sp. nov. is proposed. The type strain is a strain C1^T (=KCTC 33150^T = JCM 19173^T).