土壤微生物电化学-基因工程菌联合促进四环素降解的机理研究

抗生素污染土壤会导致其抗性基因的扩增与传播从而威胁人类健康，土壤微生物电化学系统（MES）可调控微生物代谢网络促进抗生素及其抗性基因的消减，但其代谢产物在功能菌间的跨膜转运限制了对抗生素的降解。与阳极相比土壤MES阴极的降解机理缺乏研究。本项目以四环素为典型抗生素，通过降解动力学方法研究四环素在土壤MES阴极的降解路径；采用多组学测序鉴定阴极还原条件下发生差异表达的降解基因，剖析功能基因的物种归属关系，阐明亲电菌和降解菌的内在联系；综合异源表达功能基因以验证其降解性能，并将降解基因与降解路径对应分析，揭示限制四环素降解过程的关键功能基因；以此重组功能基因构建具有高效降解能力的基因工程菌，将其接种至阴极以进一步增强对四环素的降解效能。本研究旨在结合微生物电化学系统和基因工程菌的优势以突破单一土壤修复措施的瓶颈，同步实现污染土壤治理和固废资源化，推进土壤微生物电化学/电动修复技术的发展。

The phenomenon that antibiotics contaminate the soil can give rise to the amplification and spread of antibiotic resistance genes, which results in the threat to human health. Soil microbial electrochemical systems (MES) can regulate microbial metabolic network so as to enhance the removal of antibiotics and their resistance genes, however, transmembrane transport of antibiotics’ metabolites in functional microbes restricts their biodegradation efficiency. Compared with the anode, fewer studies focus on the soil MES cathode, whose mechanism is not available. In this research, tetracycline is used as a typical antibiotic to study its degradation path in the soil MES cathode by degradation kinetics. Multi-genomic sequencing is adopted to identify the differentially expressed degradation genes in terms of cathodic reduction condition, analyze the species affiliation relationship of functional genes and clarify the internal relationship between electrophilic microbes and degrading microbes. The degradation performance is verified by heterologous expression of functional genes, and then the corresponding analysis of degradation genes and paths is conducted so as to imply the key functional genes that constrain the degradation process of tetracycline. Through recombining functional genes, the genetic engineering strain with high degradation ability is constructed and then inoculated to the cathode to further enhance the degradation efficiency of tetracycline. This study aims to combine the advantages of microbial electrochemical system and genetic engineering strain to break through the bottleneck of single soil remediation measure, simultaneously achieve the polluted soil remediation and solid waste recycling, and promote the development of soil microbial electrochemical and electrokinetic remediation technology.