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

Abstract

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 D-10 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 omega 6c (25.5 %), C-16:1 omega 7c (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)).