Study On Resistance To UV-irradiated Of Antioxidant Enzymes And Deinococcus Radiodurans

Superoxide dismutase (SOD) is an effective scavenger of free radicals. In order to determinate the protection of SOD, and the major species of free radicals, the effects of SOD were tested in the suspension of lysogenic bacteria by ultraviolet irradiation. The results indicated that SOD could significantly inhibit UV-induced of λ. prophage with a maximal inhibitory rate of 50%, and that the longer the UV-irradiated, the lower the inhibitory rate was. Meanwhile, it was found that CAT could inhibit UV-induced of A prophage with a maximal inhibitory rate of 10.7%. However, the mixture of CAT and SOD could greatly increase their inhibitory effect with a maximal inhibitory rate of 72%. In the present paper, free radicals species were analysed. It suggests that the complex free radicals were generated in the UV-induced of λ. prophage. However, 02 , ?OH and H2O2 played a dominant role in the induction.Using the techniques of PCR and DNA recombination, a recombinant plasmid carrying SOD gene from Bacillus subtilis was constructed. The plasmid was transformed into the lysogenic bacteria E. coli ( A ). With analysis of DNA fragment of recombination plasmid, Southern bloting, the results indicated that SOD gene was ligated to the plasmid pUC18. The gene could effectively expressed in lysogenic bacteria. The recombinant strain could protect itself from UV-irradiated as SOD added in the suspension of lysogenic bacteria.By electron spin resonance (ESR) and spin-trapping technique, the free radicals were detected in the suspension of the λ. lysogenic bacteria. The signals of free radical were observed when the suspension was irradiated by ultraviolet light. However, the main signals were disappeared in the suspension in the presence of SOD. It indicted that free radicals were generated in the process of UV-induced of λ. lysogenic bacteria, and that SOD could efficiently quench the free radicals.Deinococcus radiodurans was also investigated in present study. It was found that a substance extracted from Deinococcus radiodurans by different methods, could protect cells from UV-irradiated. With analysis of HPLC, ultraviolet scanning and colorization, the radiation-resistant substance was identified as carotenoid.With watershed algorithm, the linked colonies in the electrical images, which were prepared by scanning, were separated each other. Therefore, The colonies counting become an automatic method by computer. The method is a rapid, accurate, and is also suit to plaques counting on the plate.