苯系物(BTEX)长期污染对土壤和地下水微生物群落及代谢潜能的影响

苯、甲苯、乙苯和二甲苯统称为苯系物(BTEX)，是化工污染场地检出率最高的芳香族有机污染物。为研究BTEX长期污染对土壤和地下水微生物群落结构和代谢潜能的影响，采集了江苏省某搬迁化工厂的浅层土、地下水和深层土样品，利用16S rRNA基因扩增子测序和宏基因组测序技术对BTEX长期污染场地展开分析。结果表明：相比较未受污染的土壤样品，长期BTEX污染显著改变了微生物群落结构和多样性，其中以变形菌门改变最为显著。共现性网络分析表明，污染场地中随着样品取样深度的增加，微生物网络复杂性和群落稳定性降低。BTEX代谢功能基因注释表明，地下水样品中污染物代谢基因丰度和多样性更高，并且在地下水和浅层土中同时存在完整的好氧降解途径，但在地下水中厌氧降解基因的丰度更高。BTEX降解途径中benABC和bcrCBAD基因簇在浅层土中更完整，但通过构建BTEX开环的关键基因bamA的系统发育树表明，地下水中可能存在新的BTEX开环基因。这些结果证明BTEX长期污染的不同生境中存在高度多样的微生物群落与降解途径，为相关污染场地的微生物修复提供了科学依据。

Effects of Long-term BTEX Contamination on Soil and Groundwater Microbial Communities and Metabolic Potential

Benzene, toluene, ethylbenzene and xylene, collectively known as BTEX, are the aromatic organic pollutants with the most detected rates in chemically polluted areas. To investigate the effects of long-term BTEX contamination on soil and groundwater microbial community structure and metabolic potential, superficial soil, groundwater and deep soil samples from a relocated chemical plant in Jiangsu Province were collected in this study. Analysis of BTEX long-term contaminated sites using 16S rRNA gene amplicon sequencing and metagenomics sequencing techniques. The results showed that long-term BTEX contamination significantly altered the microbial community structure and diversity compared to uncontaminated soil samples, with the most significant alterations in Proteobacteria. Co-occurrence network analysis showed that microbial network complexity and community stability decreased with increasing sample depth in contaminated sites.BTEX metabolic function gene annotations indicate a higher abundance and diversity of contaminant metabolism genes in groundwater samples and the complete aerobic degradation pathway is present in both groundwater and superficial soil, but the abundance of anaerobic degradation genes is more abundant in groundwater. The benABC and bcrCBAD gene clusters in the BTEX degradation pathway are more complete in the superficial soil, but the construction of a phylogenetic tree of bamA, a key gene in BTEX opening, suggests that new BTEX ring-opening genes may be present in groundwater.These results demonstrate the existence of highly diverse microbial communities and degradation pathways in different habitats contaminated by BTEX over long term and provide a scientific basis for the microbial remediation of relevant contaminated sites.