电活性微生物协同强化降解非甾体抗炎药及降解机理

The occurrence of emerging organic contaminants in recent decades has been paid much attention due to the environmental issues they caused. Non-steroidal anti-inflammatory drugs (NSAIDs) are in the list of emerging organic contaminants and their ubiquitous detection and recalcitrance could cause health problems to human beings and potential undesirable ecological effects. Degradation by microbes is a cost-effective way but so far low-efficiency. Electrochemical active bacteria (EAB), known for their diverse and powerful electrons transfer pathway, had the potential to enhance the microbial degradation of NSAIDs in wastewaters. Therefore, the aim of the study is to enhance the degradation of benzene ring NSAIDs ibuprofen and naphthalene ring NSAIDs naproxen synergistically under micro-aerobic and anaerobic conditions with EAB. The degradation characteristics under different operation conditions would be detected. Combining the metagenomics with DNA-based stable isotope probing (DNA-SIP) would help to display the interactions among microbial communities responsible for electron transfer, NSAIDs degradation and basal metabolism and the enhanced function of EAB towards pollution degradation. Based on the genome library construction, the key functional genes for degradation would be disclosed, so as to explain the degradation mechanism for ibuprofen and naproxen at molecular level and understand the contribution of electron transfer to degradation. This study would lay a theoretical and technological foundation for the degradation of similar pollutants existing in the environments and for their fate assessment.

近些年新兴有机污染物引发的环境问题受到广泛关注，其中的非甾体抗炎药（NSAIDs）由于高频率检出和难降解而给人类健康和生态环境带来潜在危害。微生物降解是经济有效的去除方式之一，但目前报道的降解菌效率较低，电活性微生物基于多样且持续的电子传递通路有望强化污（废）水中NSAIDs的降解去除。因此，本研究将在微氧或厌氧条件下以NSAIDs中单苯环布洛芬和萘环萘普生的电活性微生物协同强化降解为目标，通过研究不同运行条件下电极微生物群落对底物的降解特性，结合组学分析和稳定同位素核酸探针技术，阐述微生物群落中参与电子传递、污染物降解和基础代谢的微生物间互作关系，电活性微生物对污染物降解的强化作用；通过基因文库构建筛选和确认污染物降解的关键基因，进而从分子角度揭示布洛芬和萘普生的降解机理和明确电子传递在降解过程的功能，为环境中此类污染物的降解去除和环境归趋评价提供理论与技术基础。

布洛芬（IBU）和萘普生（NPX）是世界高消费的非甾体抗炎药（NSAIDs），在新冠引发的发热酸痛治疗中也被大量使用，这两类药物的结构稳定而于环境中难降解转化，被列为全球前十位的难降解NSAIDs。自然水体残留的这类污染物的浓度从几十ng/L到几十µg/L。针对已有微生物处理法效率低及相关机理不明确的问题，本项目以弱电压富集电活性微生物菌群以协同强化去除IBU和NPX，研究了不同处理条件对其去除的影响，IBU和NPX的主要转化路径及参与转化的主要功能微生物菌群及相关基因，并分离高效的IBU和NPX降解转化菌株且研究了其对IBU和NPX的转化特性及对应的转化路径和机理。通过项目的实施，认为所富集的电活性生物菌群在微氧且正的外电压条件下能高效的去除IBU和NPX（效率提高>3倍），提高初始底物浓度，改变碳源或缓冲液浓度或pH均不会显著影响IBU和NPX的去除效率；IBU以氧化羟基化为主而NPX则主要为脱毒修饰；电活性微生物菌群的主要组成（相对丰度>1%）有典型的电活性菌（Geobacter，Desulfovibrio），发酵菌（Petrimonas, Acetobacterium）和潜在的降解菌（Pandoraea, Nocardiaceae）等，他们通过胞外电子、能量及辅酶、污染物脱毒等因子而构成复杂的分子生态网络。其中的真菌也与核心细菌形成互作联系并利用其多样的酶系而促进IBU和NPX的去除转化。多种氧化还原酶，脱羧酶，水解酶，细胞色素P450等参与异生化合物代谢的酶的编码基因均于核心菌属高丰度检出，他们可能参与IBU和NPX的转化。并分离鉴定了电活性微生物菌群中的一个可高效转化IBU和NPX的核心真菌属Apiotrichum sp.，该菌对IBU的转化为类似电活性微生物菌群的羟基化而对NPX则为去甲基，多组学分析推测其基因组中的多种氧化酶类（如漆酶、细胞色素C）可能负责IBU和NPX的转化,后续还需研究确认。所构建系统及所分离的功能菌为NSAIDs的强化去除和功能基因研究提供理论基础和菌种资源。