【作者】 孙继华；

【导师】 武波；

【作者基本信息】 广西大学 ， 微生物学， 2008， 硕士

【摘要】 核工业和核试验产生的大量放射性废物,可能导致严重的环境污染。开发耐辐射微生物菌株资源并研究其耐辐射的机制,不仅对阐明DNA损伤修复分子机理,而且在环境保护和生物修复、人类健康,乃至地外空间的开发和利用等方面均有十分重要意义。本实验从广西大学辐射中心多年间断受⁶⁰Co辐射(0.1 kGyh^-1)污染的水样和土壤中各分离得到一株新的耐辐射菌株WGR700和WGR702。经检测菌株WGR700和WGR702分别为革兰氏阴性杆菌和革兰氏阳性球菌;最适生长温度分别为37℃和28～32℃;（G+C）mol%含量分别为64.7mol%和60.5mol%。UV和γ射线辐射抗性试验表明菌株WGR700和WGR702都具有很强的辐射抗性。γ射线辐射下菌株WGR700和WGR702的D₁₀（10%生存率时的辐射剂量）分别为9.8 kGy和7.1 kGy。16S rDNA序列分析表明,菌株WGR700的16S rDNA（NCBI序列号:EU285374）与奇异球菌属（Deinococcus）已报道菌株16S rDNA序列相似性最高,达到87.5%～95.6%。菌株WGR702的16S rDNA（NCBI序列号:EU315117）则与沙雷氏菌属（serratia）菌株16S rDNA序列有非常高的相似性,达到94.8%～98.5%。通过对菌株WGR700和WGR702的16S rDNA序列进行测定和分析,结合电离辐射抗性试验和表型及生理生化各个方面的鉴定结果,最后确定了菌株WGR700为奇异球菌属的一个新种,命名为Deinococcus guangxiensissp.nov。菌株WGR702的鉴定结果表明其可能为沙雷氏菌属中具有耐辐射特性的一个新种。比较了不同剂量的γ射线辐射对耐辐射菌株WGR700、D.radioduransR1和辐射敏感菌株E.coli DH5α细胞可溶性蛋白含量变化的影响,结果表明耐辐射菌株与辐射敏感菌株细胞可溶性蛋白质含量变化不同。耐辐射菌株WGR700和WGR702的分离鉴定及若干特征的研究对进一步克隆耐辐射基因,了解耐辐射菌株的耐辐射机制具有一定的意义和价值。更多还原

【Abstract】 Radioactive waste produced in the nuclear industry and the nuclear tests can cause serious environmental pollutions.Researches on the radioresistant microorganisms help us to elucidate the repair mechanisms of the DNA damages caused by radiation,and also have significant effects on environmental protection,human healthy and outer space exploration.In this study,two radioresistant bacterial strains WGR700 and WGR702 were isolated from water samples and add soils of Radiation Centre of Guangxi University.The water samples and add soils had been radiated by a ⁶⁰Co irradiator(0.1 kGy h^-1)for many years.Research results showed that the strain WGR700 is Gram-negative and rod-shape while the cells of WGR702 are coccus,and Gram-positive.The optimum temperature for the growth of the strains WGR700 and WGR702 was 37℃and 28～32℃,respectively.（G+C） mol%content of the strains WGR700 and WGR702 was 64.7mol%and 60.5mol%,respectively.UV and gamma radiation survival testes showed the strain WGR700 and WGR702 are extremely resistant to ionizing radiation.The D₁₀（10%survival value）of WGR700 and WGR702 are 9.8 kGy and 7.1 kGy, respectively.Phylogenetic analysis showed that the 16S rDNA sequences of WGR700（NCBI number:EU285374）shares 87.5%～95.6%similarities with other recognized Deinococcus specieses.On the other hand,the 16S rDNA sequences of the strain WGR702（NCBI number:EU315117）have 94.8%～98.5%similarities with other recognized Serratia specieses.Based on its phenotypic,biochemical and physiological characteristics,it is proposed that the new isolated strain WGR700 should be classified as a novel member in the genus Deinococcus with the name Deinococcus guangxiensis sp.nov.For the strain WGR702,it might be classified as a novel species of Serratia.The effect of gamma-radiation on the water soluble protein of the radioresistant strains WGR700,D.radiodurans R1 and radiosensitive strain E.coli DH5αcells has been compared,respectively.The results showed that the change of water soluble protein concentration in radioresistant strains and radiosensitive strain cells were different after gamma-radiation.The studies on the two radioresistant bacteria strains WGR700 and WGR702 will have the significance for cloning radioresistant genes and realizing the radioresistance mechanism.更多还原