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

Abstract:

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 WGR700T 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 WGR700T is of rod-shape, Gram-negative, non- spore-forming, non motile, aerobic and red-pigmented. The optimum temperature and pH for strain WGR700T growth is 37°C and pH7.0, 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 16:1ω7c, 16:0, 15:1ω6c, iso-15:0 and iso-17:0. DNA of strain WGR700T had a G+C content of 64.7mol%. WGR700T 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 WGR700T (= CGMCC 1.7045T = CICC 10360T = JCM 15082T ).

Key words:Keywords: radioresistant bacterium; Deinococcus; phylogenetic analysis