砷尾矿污染土壤的细菌群落结构多样性及其相关环境影响因子分析

以湖南石门雄黄尾矿污染土壤为对象,研究纵向不同深度、横向不同距离土样中的重金属污染程度以及细菌群落结构变化规律,查明砷污染土壤的核心微生物组成并将其与土壤理化指标进行共存网络图分析。结果表明:该尾矿区的土壤各项重金属指标严重超标,尤以铅(626.54 mg·kg^?1,Ei=105.48)、砷(1804.75 mg·kg^?1,Ei=565.75)、镉(31.46 mg·kg^?1,Ei=7491.5)的生态危害性最强;土壤采样深度与重金属综合潜在生态风险指数(RI)呈显著正相关(r=0.79,P=0.000),而横向样品中RI与采样距离显著负相关(r=?0.85,P=0.000)。在污染土壤中,变形杆菌门(Proteobacteria,54.35%±17.16%)和放线杆菌门(Actinobacteria,22.39%±10.64%)占主导地位,属层级中假单孢杆菌属(Pseudomonas,16.47%±11.84%)、不动杆菌属(Acinetobacter,8.07%±7.11%)以及硫酸状杆菌属(Acidithiobacillus,7.53%±14.68%)相对丰度较高;而26个共享类群占据了该尾矿污染土壤中微生物群落总平均相对丰度90%以上,尽管不同属的具体相对丰度在不同样品间的分布趋势差异较大。纵剖采集的污染土样中,铁原体属(Ferroplasma)、硫酸状杆菌属(Acidithiobacillus)、硫化杆菌属(Sulfobacillus)、乳杆菌属(Lactobacillus)和硝化螺旋菌属(Nitrospira)占优势,与理化的共存网络图分析(相关系数|r|≥0.6,P<0.05)显示部分类群与亚铁、游离态砷和镉成显著正相关,而与pH成显著负相关;横向采集的土样中,以嗜酸菌属(Acidiphilium)、假单孢杆菌属(Pseudomonas)、棒状杆菌属(Corynebacterium)、硫杆菌属(Thiobacillus)等为主,部分类群与总砷、铅成显著正相关,而与结合态或包蔽型砷成显著负相关。综上,该研究不仅对目标区域尾矿不同重金属污染程度进行了分析,同时探讨了污染土壤中核心响应类群的组成多样性,为筛选潜在重金属抗性菌群或工程菌群提供理论基础。

Analysis of Microbial Community Structure and Environmental Impact Factorsof Arsenic Mine Tailings

In the study,we investigated the degrees of heavy metal pollution and patterns of microbial community composition at various depths and distances in a Hunan shimen realgar mine tailings,to identify the core microbes in arsenic contaminated soil and the soil physico-chemical properties influencing these microbes.The results showed that the heavy metal indexes in the mine tailings were remarkably higher than the standards,especially for lead(626.54 mg·kg^?1,Ei=105.48),arsenic(1804.75 mg·kg^?1,Ei=565.75),and cadmium(31.46 mg·kg^?1,Ei=7491.5).There was a significant positive correlation between soil sampling depth and the comprehensive potential ecological risk index(RI)of heavy metals(r=0.79,P=0.000),while a significant negative correlation between RI and sampling distance was detected(r=?0.85,P=0.000).The dominant phyla in all samples were Proteobacteria(54.35%±17.16%)and Actinobacteria(22.39%±10.64%).As for genus level,the relative abundance of Pseudomonas(16.47%±11.84%),Acinetobacter(8.07%±7.11%),and Acidithiobacillus(7.53%±14.68%)were relatively high.The 26 taxa shared in all samples accounted for more than 90%of the total average relative abundance of the whole microbial communities,although the relative abundance of each specific genera varied largely among different samples.Specifically,Ferroplasma,Acidithiobacillus,Sulfobacillus,Lactobacillus,and Nitrospira were dominant in soil samples collected at different longitudinal depths.The coexistence network analysis(correlation coefficient r≥|0.6|,or P<0.05)revealed that some taxa were positively correlated with concentrations of ferrous,free arsenic,and cadmium,but were negatively correlated with pH.As for soil samples collected transversely,Acidiphilium,Pseudomonas,Corynebacterium,and Thiobacillus were the most abundant lineages.Some taxa were positively correlated with total arsenic and lead,while negatively correlated with combined or encrusted arsenic.In summary,we analyzed the environmental pollution risk of multiple heavy metals originated from the arsenic mine tailings and investigated the correlations between heavy metals and the core microbes,which might provide a theoretical basis for screening potential heavy metal resistant bacteria or engineered bacteria.