低剂量辐射下土壤细菌群落及其功能基因的响应

Soil Microbial Community and Functional Gene Response to Low-Radiation-Dose Stress

为研究低剂量辐射对土壤微生物组成与丰度的影响,分析微生物组中对辐射胁迫的主效基因,本研究从新疆和布克赛尔蒙古自治县关闭回填的铀矿场采集了辐射剂量从7.71 mSv/y到15.07 mSv/y不等的土壤样品.应用宏基因组测序结合生物信息学分析方法,发现低剂量辐射环境下的土壤中变形菌门、放线菌门、拟杆菌门、芽单胞菌门、绿弯菌门和酸杆菌亚门为优势菌门,其丰度总和占比达80%以上.属水平上,假单胞菌属数量最多,丰度最高,占31.0%;芽孢杆菌属次之,为11.0%;肠杆菌属为10.3%.辐射剂量高的土壤中,微生物OTU数量最高,多样性丰富度最大.土壤样品中微生物群落碳氮源的代谢强度也与辐射剂量呈正相关.宏基因组测序及分析结果表明:辐射土壤样品中微生物功能基因达到7558个,比正常辐射水平对照组高11.3%,高辐射样品中碱基切除修复通路中的mug(TDG/mug DNA糖基化酶家族蛋白)的数量显著高于对照组和低辐射组.从辐射土壤样品中分离出30个属的可培养菌145株,其中一株藤黄微球菌Micrococcus luteus R17具有辐射和盐碱逆境的耐受性,可作为潜在的底盘菌株加以改造.

To study the effects of low-dose radiation on soil microbial composition and abundance,and to analyze the primary genes in the microbiome that respond to radiation stress,soil samples with radiation doses ranging from 7.71 mSv/y to 15.07 mSv/y were collected from uranium mines in Xinjiang and Buccaneer County that were closed for reclamation in this study.Metagenomics Sequencing combined with bioinformatics analysis was applied,and it was found that the 6 phyla of Proteobacteria,Actinobacteria,Bacteroidetes,Gemmatimonadetes,Chloroflexi andAcidobacteria subphylum were the dominant in the soil under low dose radiation environment,with their com-bined abundance accounting for more than 80%of the total.At the genus level,Pseudomonasspp.is the most abundant and highest in abundance,accounting for 31.0%,followed by Bacillus spp.with 11.0%and Enterobacte-riaceae with 10.3%.The highest number of microbial OTUs and the greatest diversity richness were found in soils with high radiation doses.The metabolic intensity of carbon and nitrogen sources of microbial communities in soil samples was also positively correlated with radiation dose.The number of mug(TDG/mug DNA glycosylase family proteins)in the base excision repair pathway was significantly higher in the irradiated soil samples than in the control and low irradiation groups.One strain of Micrococcus luteus R17,145culturable strain of 30 genera,was isolated from the irradiated soil samples,which was resistant to radiation and saline-alkali stressand could be modified as a potential chassis strain.