高放废物处置库膨润土中微生物多样性分析

Microbial Community Diversity in Buffer Material of Bentonite for High-level Radioactive Waste Disposal

膨润土由于具有极低的渗透性和优良的核素吸附等性能被国际上选作高放废物地质处置库的缓冲材料。为了评价工程屏障材料膨润土中微生物对高放废物地质处置安全性的影响,文章对中国内蒙古高届子膨润土中微生物进行多样性分析。采用宏基因组学方法,直接从内蒙古高届子膨润土样品中提取总DNA,扩增16S r RNA V3-V4区后用Illumina Miseq平台进行高通量测序,并对微生物多样性和丰度进行生物信息学分析。膨润土中检测到31个门,58个纲,76个目,172个科,495个属,样本菌群多样性较高,主要是奇古菌门(Thaumarchaeota)、变形菌门(Proteobacteria)、广古菌门(Euryarchaeota)、厚壁菌门(Firmicutes)、放线菌门(Actinobacteria),这5个门微生物占95%,其中奇古菌门的亚硝化球菌属(Nitrososphaera)约占整个菌群的60%。此外还鉴定出变形菌门的5个亚类群:α-,β-,γ-,δ-,ε-Proteobacteria,包含硫杆菌属(Thiobacillus)和脱硫孤菌属(Desulfovibrio)等。通过宏基因组方法直接对高放废物地质处置库的缓冲材料膨润土中微生物进行鉴定和多样性分析,发现膨润土中含有较丰富的微生物,古细菌为优势菌群,具有硫酸盐还原和铁氧化等功能,在深地质环境中可产生大量硫化氢和甲烷气体,可能诱发金属包装的腐蚀,进而影响高放废物处置库的安全性。

Objective Bentonite was selected for buffer materials because of its low permeability and excellent sorption for High-level radioactive waste repository in many country. Microorganisms may significantly influence the function of a future deep repository for spent nuclear fuel. Therefore microbial community diversity in buffer material of bentonite was analyzed.Methods Gaomiaozi bentonite samples from the site xinghe county were collected,and microbial community diversity based on 16 S r RNA V3-V4 region in metagenomics was analyzed with Illumina Miseq. Results Thirty-one phyla, fifty-eight class-es,seventy-six orders, one hundred and seventy-two families and four hundred and ninety-five genera were detected in the bentonite samples. Bacterial diversity was high in the bentonite. Thaumarchaeota, Proteobacteria, Euryarchaeota, Firmicutes and Actinobacteria were predominant in the samples. And the archaeota showed 60 percent of all. The alpha,beta, gamma and delta groups of Proteobacteria bacteria were classified, include Thiobacillus and Desulfovibrio. Conclusion The results suggest that bentonite samples from the site xinghe county contain a variety of microorganism. There were sulphate-reducing bacteria and iron-reducing bacteria which may significantly influence the function of stainless steel materials, and the ra-dionuclide migration.