产甲烷条件下多环芳烃厌氧降解过程与微生物学机制

Polycyclic aromatic hydrocarbons (PAHs) have been found as a kind of important pollutants present ubiquitously in many anoxic and anaerobic environments, especially in the electron acceptor-lacking environment (anaerobic methanogenesis condition). PAHs biodegradation under the anaerobic methanogenesis condition has been considered as one of the major attenuation fate of PAHs in anaerobic environment. However, the knowledge of PAHs degradation mechanism or related microbiology under this anaerobic condition is rare. This project will collect samples from typical anaerobic environments such as anaerobic sludge in sewage plant, contaminated soil in oil field and in coastal sediment and so on, and the major research strategy is described as following: 1) the distribution, degradation potential and species diversity of anaerobic PAHs degraders in different samples will be investigated, and the appropriate samples will be utilized to select the anaerobic PAHs degrading consortium both with the efficient ability of anaerobic PAHs degradation and the ability of methane production; 2) small core flora with the anaerobic degradation-methanogenesis ability and pure strains with the anaerobic PAHs degradation ability will be screened and isolated by the multiple dilution method combined with anaerobic agar vibration culture method; 3) for the analysis of PAHs degradation mechanism by the isolated pure strains under anaerobic methanogenesis condition, 13C stable isotope probing and high throughput sequencing technology will be employed to identify degradation intermediates and to obtain genomic information of the strains, respectively; 4) the screened small core flora will be analyzed to study the anaerobic PAHs degradation-methanogenesis pathway and mutual relations between microorganisms. The findings in this project will provide an important theoretical support for evaluation of PAHs fate in anaerobic environments and for PAHs pollution control or remediation under anaerobic conditions.

多环芳烃(PAHs)广泛存在于各类缺氧和厌氧环境中，特别是缺乏电子受体的环境中（厌氧产甲烷环境），厌氧产甲烷条件下PAHs的生物降解是PAHs在自然界中衰减的主要途径之一。目前人们对这一厌氧生物降解过程、机理及相关的微生物学机制知之甚少。课题拟从油田区污染土壤、海岸沉积区、污水厂厌氧污泥等典型厌氧环境取样，开展以下研究工作：1）分析不同环境中PAHs厌氧降解潜力及降解微生物多样性，从合适的环境样品中富集筛选出具有PAHs厌氧降解-产甲烷能力的富集菌群；2）利用倍比稀释结合厌氧琼脂振荡法分离具有厌氧降解-产甲烷能力的核心小菌群，以及具有厌氧降解PAHs的纯菌；3）利用13C标记技术研究纯菌厌氧降解PAHs的途径和机理；4）利用核心降解小菌群研究PAHs厌氧降解-产甲烷的过程及微生物学机理。课题研究成果将为评价PAHs在厌氧环境中的归趋，开发控制和修复厌氧环境中PAHs污染提供重要的理论支持。

多环芳烃 （PAHs）广泛存在于各类缺氧和厌氧环境中，特别是缺乏电子受体的环境中（厌氧产甲烷环境），厌氧产甲烷条件下PAHs的生物降解是PAHs在自然界中衰减的主要途径之一。但是，目前人们对PAHs厌氧生物降解过程、机理及相关的微生物学机制知之甚少。.本研究以菲为唯一碳源及能源，分别以硫酸根、硝酸根、三价铁离子和二氧化碳为电子受体进行微生物富集培养并筛选纯化，成功从石油污染土壤和污水处理厂污泥中分别富集并筛选出两个硫酸盐还原（SR）条件下菲厌氧降解富集小菌群、一个硝酸盐还原（NR）条件下菲厌氧降解富集小菌群、一个三价铁离子还原（FR）条件下菲厌氧降解富集小菌群和一个产甲烷还原（MR）条件下菲厌氧降解富集小菌群，并对以上四个小菌群的菌落结构及菲的生物代谢途径进行了分析,阐明了四种还原条件下微生物降解PAHs途径、主要功能菌株和影响因素。.在此基础上，通过平板分离的方式首次获得了四株NR条件下菲的厌氧降解纯菌，一株SR条件下菲的厌氧降解纯菌，一株可以在厌氧条件下利用三价铁为电子受体、好氧条件下利用氧气为电子受体降解菲的兼性厌氧纯菌，一株可以同时以硫酸根、三价铁和四价锰为电子受体的厌氧降解菲的纯菌，以及一个高度纯化的MR条件下菲的厌氧降解小菌群（仅由一株细菌和一株古菌组成），分别对以上的纯菌和小菌群进行了代谢特征，代谢产物检测，全基因组测序分析，反转录分析，得到了不同还原条件下的菲的两条厌氧降解途径，羧基化途径和甲基化途径，以及与羧基化和甲基化代谢途径及相对应的关键基因和酶的信息。上述研究成果均未见报道。课题研究成果将为评价PAHs在厌氧环境中的归趋，开发控制和修复厌氧环境中PAHs污染提供重要的理论支持。