Isolation and identification of a new radiation-resistant bacterium Deinococcus guangriensis sp.nov. and analysis of its radioresistant character.

ABSTRACT

OBJECTIVE: To isolate and identify a new ionizing-radiation resistant strain capable of surviving under highly ionizing radiation conditions as UV and gamol/La radiation and to characterize its radioresistant properties. METHODS: The isolates were sampled from Radiation Centre of Guangxi University, Nanning, China, and the medium used for isolation and cultivation of the bacterium was General Bacterial Medium (GBM). The new ionizing-radiation resistant strain WGR700(T) was identified by its morphology, biochemical and physiological characteristics, fatty acids, G + C content of DNA, UV and gamol/La radiation resistance and 16S rRNA gene sequence homology. RESULTS: The strain WGR700(T) is of rod-shape, Gram-negative, non-spore-forming, non motile, aerobic and red-pigmented. The optimum temperature and pH for strain WGR700(T) growth is 37 degrees C and pH 7.0, respectively. The predominant respiratory quinone is MK-8 and its cell well contains ornithine. The major cellular fatty acids found in the cell wall are 161omega7c, 160, 151omega6c, iso-150 and iso-170. DNA of strain WGR700(T) had a G + C content of 64.7 mol%. WGR700(T) was highly resistant to UV ( > 728 J/m2 ) and gamol/La radiation ( D10 = 9.8 kGy). Phylogenetic analysis of the 16S rRNA gene sequences showed 87.1-95.6% similarities with other recognized Deinococcus species. CONCLUSION: Based on the high 16S rRNA gene sequence divergence and phenotypic differences, it is proposed that the new isolated strain should be classified as a novel member in the genus Deinococcus with the name Deinococcus guangxiensis sp. nov. The type strain is WGR700(T)( = CGMCC 1.7045T = CICC 10360T = JCM 15082T) .