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The Response of Radiation Resistant Bacteria Deinococcus Sp. to Oxidative Stress / The Response of Deinococcus So. to Oxidative Stress

Bacteria of the radiation resistant genus π˜‹π˜¦π˜ͺ𝘯𝘰𝘀𝘰𝘀𝘀𝘢𝘴 have a high resistance to the lethal and mutagenic effects of many DNA damaging agents, however, the mechanisms involved in the response of these bacteria to oxidative stress are poorly understood. To investigate antioxidant enzyme responses in π˜‹π˜¦π˜ͺ𝘯𝘰𝘀𝘰𝘀𝘀𝘢𝘴 sp., the types of catalase and superoxide dismutase (SOD) produced by these bacteria were identified by visualization of the enzyme activities on non-denaturing polyacrylamide gels (PAGE) and the growth inhibition of selected strains by various concentrations of hydrogen peroxide and paraquat (a superoxide generating agent) was tested. π˜‹π˜¦π˜ͺ𝘯𝘰𝘀𝘰𝘀𝘀𝘢𝘴 sp. were found to be more resistant to hydrogen peroxide and more sensitive to paraquat than 𝘌𝘴𝘀𝘩𝘦𝘳π˜ͺ𝘀𝘩π˜ͺ𝘒 𝘀𝘰𝘭π˜ͺ K12. They possess relatively high levels of catalase and exhibit similar electrophoretic patterns on catalase zymograms compared to 𝘌. 𝘀𝘰𝘭π˜ͺ, but all the tested strains produce only one SOD except π˜‹π˜¦π˜ͺ𝘯𝘰𝘀𝘰𝘀𝘀𝘢𝘴 𝘳𝘒π˜₯π˜ͺ𝘰𝘱𝘩π˜ͺ𝘭𝘢𝘴 which produces two. The two catalases of π˜‹π˜¦π˜ͺ𝘯𝘰𝘀𝘰𝘀𝘀𝘢𝘴 𝘳𝘒π˜₯π˜ͺ𝘰π˜₯𝘢𝘳𝘒𝘯𝘴 were found to be regulated independently. Cultures of π˜‹. 𝘳𝘒π˜₯π˜ͺ𝘰π˜₯𝘢𝘳𝘒𝘯𝘴, when pretreated with sublethal levels of hydrogen peroxide, became relatively resistant to the lethal effects of Hβ‚‚Oβ‚‚ and exhibited higher levels of catalase than untreated control cultures. The pretreated cells were also relatively resistant to UV-and Ξ³-ray-mediated lethality. These results suggest that π˜‹π˜¦π˜ͺ𝘯𝘰𝘀𝘰𝘀𝘀𝘢𝘴 sp. possess inducible defense mechanisms against the deleterious effects of oxidants and ionizing and UV radiation. The resistance to the lethal effects of hydrogen peroxide and UV radiation can not be induced by pretreatment with sublethal levels of hydrogen peroxide in π˜‹. 𝘳𝘒π˜₯π˜ͺ𝘰π˜₯𝘢𝘳𝘒𝘯𝘴 rec30 mutant. Effects of manganese and magnesium on the growth and catalase activity of π˜‹. 𝘳𝘒π˜₯π˜ͺ𝘰π˜₯𝘢𝘳𝘒𝘯𝘴 were determined. Homology between 𝘌. 𝘀𝘰𝘭π˜ͺ catalase and SOD genes and those of π˜‹π˜¦π˜ͺ𝘯𝘰𝘀𝘰𝘀𝘀𝘢𝘴 sp. was tested by Southern blot analysis using previously cloned genes from 𝘌. 𝘀𝘰𝘭π˜ͺ. / Thesis / Master of Science (MS)

Identiferoai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/22938
Date09 1900
CreatorsWang, Ping
ContributorsSchellhorn, H. E., Biology
Source SetsMcMaster University
LanguageEnglish
Detected LanguageEnglish
TypeThesis

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