抗生素-重金属复合污染对土壤微生物的生态毒理效应及其作用机制研究

近年来，随着畜禽粪便的频繁大量农用，土壤中抗生素与重金属等化合物的复合污染问题日趋严重。这将对土壤生态系统稳定性及其功能造成严重威胁。为此，本项目拟在前期研究的基础上，以土壤氨氧化菌群功能基因amoA为生物标志物，以典型土壤功能NOR值的确定、氨氧化微生物对Cu-SDZ/SMA复合污染响应的分子生态特征研究为主线，采用定量PCR、Miseq测序、mRNA转录等技术手段，在分子水平上分析Cu和典型的磺胺类抗生素的复合污染生态毒理效应及其联合作用机制；建立抗生素和重金属复合污染的土壤生态毒理效应诊断的指标体系，为土壤抗生物-重金属污染复合污染的生态风险评价以及畜禽粪便的科学管理提供理论支持。

With the rapid development of livestock and poultry industry in China, residues of veterinary antibiotics (Such as suflonamides, tetracyclines, etc) and heavy metals (such as Cu, Zn, etc ) in animal manure eventually get into soils, which pose a serious potential threat to soil ecology and human health. Considering their persistence in soils and associated impacts on soil ecosystem, it is necessary to investigate the ecotoxicology of binary antibiotics and heavy metal mixtures on soil microbial communities and function. .Nitrification is a key process in the soil nitrogen (N) cycle. Ammonium-oxidizing microbes (AOM), including AOB and AOA, have been identified as the key group that controls the rate-limiting step of nitrification, which is catalyzed by the ammonia monooxygenase (AMO). Moreover, it was reported that the abundance of AOB and AOA could serve as a relevant and cost-effective bio-indicator for soil monitoring. Therefore, it is significant to research the effect of sulfonamides and Cu on ammonia oxidizing microbes (AOB and AOA) and their activities using functional amoA gene..In this study, we selected Copper, sulfadiazine (SDZ) and sulfamethazine (SMA) as the tested toxic chemicals; we select two type soils sandy soil and clay soil as the tested soils, which are the typical soils in China. The soils will be collected from eight locations, which have different characteristics in terms of pH, texture, and organic matter content, and nitrate and ammonium level. All fields were used for wheat and corn cropping and subjected to (1:1) crop rotation. we evaluate the toxic effects of Cu, SDZ/SMA and their binary mixtures using two novel molecular techniques: 1) an assay based on reverse-transcription qPCR, which quantifies the abundance of amoA functional gene transcripts, and 2) an assay evaluating the diversity of bacterial communities. For functional genes, we quantified amoA transcripts from both bacteria and archaea, and for diversity, we evaluated the Miseq sequencing of the V3 region of the 16S ribosomal RNA (rRNA) gene—in both cases in response to treatment with the Cu, SDZ/SMA and their binary mixtures. Moreover, we will measure key soil chemical parameters and soil nitrification potential activities. The final aims is 1) to build a large dataset suitable for assessments of soil functioning in agricultural soils, and to provide a tool to establish the NOR of soil functioning, allowing the detection of soils undergoing disturbances; 2) to determine the joint toxic effects of Cu-SDZ/SMA on ammonia oxidizing communities and their function at molecular level. This study will provide a theoretical basis for ecological risk assessment of contaminated soils with heavy metals and veterinary antibiotics, and the reference for the ecological risk evaluation and soil pollution control with field application of manures.