Isolation and identification of radiation resistant Bacillus aryabhattai T61 from Tibetan soil

Abstract:

[Objective] To identify strain T61 which was isolated from Tibetan soil and analyze its radiation resistance. [Methods] First, investigate the morphological and biochemical characteristics of T61; Second, amplify the sequence of 16S rRNA gene and construct the phylogenetic tree; Third, determine compositions of fatty acids, DNA G+C content and DNA-DNA hybridization; Finally, analyze T61 survival curve after exposure to UV radiation. [Results] T61 cells were rod-shaped, 2 μm in length, 1 μm in diameter, gram-positive and endospore-forming. Strain T61 had a G+C content of 38.02%. The main Fatty acids were C14:0 iso, C15:0 iso and C15:0 anteiso. Phylogenetic analysis of the 16S rRNA gene showed that strain T61 had 99.93% and 99.53% similarities with Bacillus aryabhattai B8W22T and Bacillus megaterium IAM13418T, respectively. At the whole genome level, the DNA-DNA relatedness between T61 and Bacillus aryabhattai B8W22T was 81.4%, but only 50.3% with Bacillus megaterium IAM13418T. D10 values of T61 after exposure to UV was 100 J/m2, much higher than those of radiation-sensitive Escherichia coli K12 and B. subtilis. [Conclusion] Strain T61 was highly resistant to UV radiation. It was identified as Bacillus aryabhattai species, and was proposed the name Bacillus aryabhattai T61.

Key words:Bacillus, Radiation resistance, Isolation and identification, DNA-DNA hybridization