Construction of the gene drb0099 deleted mutant and adversity analysis in the extremely radioresistant bacterium Deinococcus radiodurans

Abstract:

Deinococcus radiodurans R1 has extraordinary resistance to radiation. DRB0099 might play an important role in protecting the bacterium against radiation. To verify the inference, we deleted drb0099 and constructed the mutant. Comparing with the wild type, the mutant grew more slowly in the beginning cultivation stage (0~16 h) under normal conditions. After being cultivated for 16 h, the mutant grew faster than the wild type. The biomass concentration of the wild type was always higher than that of the mutant. The mutant cell’s fission during the growing phase might be blocked. When treated with UV, although Deinococcus radiodurans R1 cultures’ survival fraction was lower with UV treatment time increased, the survival fraction was much higher than that of⊿drb0099. The wild type could repair DNA double strands breaks better than the mutant. The gene drb0099 might directly relate with the DNA repair system. The mutant was more sensitive to H2O2 than the wild type. The wild type could better protect protein and DNA against reactive oxygen species (ROS) or in DNA repair. When treated with low concentration of H2O2, although the survival fraction of both R1 and the mutant decreased, the difference was small. However, with the concentration of H2O2 increased, the difference value increased. The mutant without drb0099 was more easily injured than the wild type with ROS increased. Under UV or H2O2 treatment, DRB0099 could protect protein and DNA from oxidation.