典型砷污染场地及周边生境土壤微生物群落结构及分子网络特征

Characteristics of microbial community structure and molecular ecological network in typical arsenic-contaminated sites and surrounding habitats

为了解砷污染严重环境下不同生境土壤微生物群落结构差异,选择广西贺州某砷污染场地附近裸地、农田、草地和林地4种生境下的土壤,利用16S rRNA Illumina高通量测序技术和分子生态网络的方法,比较4种生境土壤微生物群落结构和组成的差异、微生物物种间的相互作用关系以及微生物与环境因子之间的相关性。结果表明:4种生境土壤均呈酸性,裸地土壤酸性最强。裸地土壤微生物群落的多样性和丰富度最低,农田土壤微生物群落多样性和丰富度最高。细菌门水平上,农田最关键菌门为放线菌门,而其他3种生境土壤最关键菌门为绿弯菌门,且相对丰度均最高。分子生态网络结构分析表明,农田土壤的网络节点数、连接数和模块数最少,联系较为简单,系统稳定性较低,林地土壤和草地土壤的连接数和平均连接度较高,微生物物种之间的联系更为复杂,系统稳定性更高。4种生境土壤微生物物种间均主要呈现出相互合作关系。冗余分析表明,环境因子中,土壤pH、速效K、全N和有机质显著影响了土壤微生物的群落结构。

To clarify the differences in community structure of soil microorganisms in different habitats under the background of severe arsenic contamination,we collected soil samples in four different habitats(bare land,farmland,grassland and forest)near an arsenic-contaminated site in Hezhou,Guangxi.The 16S rRNA Illumina high-throughput sequencing technology and molecular ecological network were used to compare the structure and composition of soil microbial communities,the interactions among microbial species,and the correlations between microorganisms and environmental factors.The results showed that soils of the four habitats were acidic,with the bare land soil being the most acidic.The diversity and richness of microbial communities were lowest in bare land soils and highest in farmland soils.With respect to relative abundance at the bacterial phylum level,the most critical phylum was Actinobacteriota in farmland and Chloroflexi in the other three habitats.The analysis of molecular ecological network structure showed that the network of farmland soil had the lowest number of nodes,connections,and modules,with simpler connections and lower system stability,while forest soil and grassland soil had higher connections and average connectivity,with more complex connections among microbial species and higher system stability.Soil microorganisms in the four habitats mainly showed cooperative relationships.Results of redundancy analysis showed soil pH,available K,total N,and soil organic matter contents significantly influenced soil microbial community structure.