水稻土中五氯酚还原与矿化的微生物代谢机制

Pentachlorophenol is one of highly toxic and persistent POPs. Effective removal of PCP has became one worldwide environmental problem and challenge which has been paid urgent attention and should be resolved as soon as possible. Reduction and mineralization driven by microbes are the important way to elimination of pentachlorophenol in paddy soil. This application uses three typical of paddy soil (granite, shallow sea sediments and delta alluvial ) in the Pearl River Delta as the research objects, employing ribosomal barcoding pyrosequencing of DNA/RNA with 13C stable isotope probing, to explore the microbial community structure, phylogenetic diversity, functional bacteria, functional gene and activity evolution in the process of the reduction and mineralization of PCP under anaerobic condition. This work will explore the microbial reduction and mineralization mechanism of PCP in the paddy soil, deeply understand the environment behavior of PCP in the paddy soil, and provide technical support for the sustainable use of polluted paddy soil.This innovation is characterize species relative activity with corresponding 16S rRNA gene ratio of pyrosequencing sequences above DNA/RNA level, which helps to explore the contribution of different microbial taxa in the process of reduction and mineralization of PCP. This work will enrich the detailed microbial mechanism of aromatic polychlorinated compounds in such a system.

五氯酚是一种高毒、难降解有机氯污染物，如何消除土壤中的五氯酚已成为亟需解决的环境问题。微生物作用下的还原与矿化过程是水稻土中五氯酚消除的重要途径。本项目以珠三角花岗岩、浅海沉积物、三角洲冲积物发育的三类典型水稻土作为研究对象，采用基于DNA/RNA稳定性同位素探针技术结合高通量测序技术，从群落结构、功能微生物及其活性三个层面，研究厌氧条件下五氯酚还原和矿化过程中微生物群落物种组成、系统发育多样性、功能微生物、功能基因及其活性的演变，阐明水稻土中五氯酚的微生物代谢机制，为深入理解水稻土中五氯酚的环境行为提供依据，同时为污染水稻土的可持续利用提供技术支持。本研究的创新点在于：在物种组成及活性两个水平上分析五氯酚还原和矿化微生物学机制；以RNA水平上物种的相对活性为指标，阐明不同微生物类群在五氯酚还原和矿化过程中的贡献；丰富了土壤芳香族有机氯污染物生物代谢机制的研究。

五氯酚是一种高毒、难降解有机氯污染物，被广泛用作除草剂、杀虫剂等，已造成了湿地、水体、土壤的污染，并且威胁到人体的健康。如何消除土壤中的五氯酚已成为亟需解决的环境问题。本项目通过以五氯酚为目标污染物，利用T-RFLP、克隆文库、定量PCR、DNA-SIP以及高通量测序等分子生物学技术，探究了珠三角水稻土中五氯酚还原脱氯和矿化过程及其微生物群落结构和关键功能菌群丰度变化，解析土壤环境中有机氯污染消除的微生物学机制。结果表明(1)氧化铁游离度与活化度、母质与土地利用方式是影响五氯酚还原转化速率的关键因素；(2)变形菌门(Proteobacteria)、厚壁菌门 (Firmicutes)和广古菌门(Euryarchaeota)是五氯酚还原脱氯过程中主要微生物菌群，梭菌(Clostridium)是五氯酚还原脱氯过程中优势微生物，铁还原菌和脱氯菌参与了五氯酚还原脱氯转化过程；(3)反应初期五氯酚发生开环，Dechloromonas和Methanosaeta在PCP矿化过程中对同化13C具有促进作用；(4)腐殖质的添加显著促进PCP的还原及矿化，且PCP的还原速率与腐殖质的碳含量成正相关；不同来源腐殖质能够显著影响微生物群落结构及其参与五氯酚矿化的微生物。以上研究结果阐明了水稻土中五氯酚的微生物代谢机制，为深入理解水稻土中五氯酚的环境行为，研发高效的有机氯污染物脱毒技术提供重要的科学依据。