氢噬胞菌H7砷氧化和苯甲酸及其衍生物降解的代谢偶联机制

Arsenic and aromatic compounds often coexist in the environment. So far, the mechanisms of arsenic transformation and aromatic compounds degradation are well understood, however, there is almost no knowledge of the co-metabolic mechanisms of both arsenic and aromatic compounds. Bacterial arsenite oxidation is the process of oxidizing the more toxic As(III) to the less toxic As(V), which is a detoxification process. In addition, As(V) is easier to be removed during treatment. Previously, we found that Hydrogenophaga sp. H7 can oxidize As(III) and degrade benzoate and 3-/4-hydroxybenzoate. Adding As(III) promotes the degradation rate of these three aromatic compounds. With the addition of benzoate and 3-/4-hydroxybenzoate, As(III) and As(V) transformed between each other, but the final product is As(V) when the degradation of the aromatic compounds is complete. The genome of strain H7 contains arsenic gene islands with multiple arsenic transformation functions and the genes that degrade the above aromatic compounds. Transcription analysis also predicts potential coupling mechanisms between As(III) oxidation and benzoate and 3-/4-hydroxybenzoate degradation. Based on these preliminary results, in this project, we will use metabolomics, gene knockout and complementation, heterogeneous expression, enzyme activity assay, arsenic transformation, aromatic compound degradation and redox potential assay, to identify the coupling-metabolic mechanisms of As(III) and degradation benzoate etc.. Determination of the co-metabolic mechanisms of arsenic and aromatic compounds is a challenging project which has a significant innovative theoretical scientific value and provides bacterial resources and scientific basis for the remediation of arsenic and aromatic compound pollution.

砷和芳烃化合物常在环境中共存，目前对细菌砷转化机制和芳烃降解机制已有一定认知，但细菌砷和芳烃共代谢的机制还基本为空白，值得解析。细菌砷氧化是将毒性强的As(III)氧化为毒性弱的As(V)的解毒过程，且As(V)较易被处理去除。我们前期发现氢噬胞菌H7既能氧化As(III)又能降解苯甲酸、3-/4-羟基苯甲酸；加As(III)促进对这三种芳烃的降解；加苯甲酸、3-/4-羟基苯甲酸造成As(III)和As(V)间转化，但芳烃降解完后砷转化稳定为As(V)。H7菌基因组含有多种砷转化、抗性的砷基因岛及降解以上芳烃的基因簇，转录分析也预示了潜在的偶联机制。本课题将在此基础上，利用代谢组学、基因敲除与互补、异源表达、酶活分析、转录、砷转化、芳烃降解分析和氧化还原电位分析等技术，阐明H7菌As(III)氧化和苯甲酸等降解的代谢偶联机制。其结果具有理论创新性并为砷和芳烃污染修复提供菌种资源和科学依据。

砷和芳烃化合物是环境中普遍存在的污染物，且常在环境中共存。许多细菌能氧化高毒As(III)为低毒的As(V)或降解芳烃化合物为无毒的小分子物质。目前对细菌砷转化机制和芳烃降解机制已有一定认知，但细菌砷和芳烃共代谢的机制还基本为空白。本课题的主要目标是阐明细菌砷代谢和苯甲酸及其衍生物降解的代谢偶联机制及探究微生物修复砷和芳烃化合物污染的能力。氢噬胞菌H7是一株砷氧化型细菌，其能降解苯甲酸（BA）、3-羟基苯甲酸（3-HBA）和4-羟基苯甲酸（4-HBA），且在加As(III)时能够促进菌株H7降解BA, 3-HBA和4-HBA的降解。为了阐明砷转化和芳烃化合物降解之间的关联机制，本研究以菌株H7为模式菌，研究了As(III)促进BA, 3-HBA和4-HBA降解的机制，并探究了其修复砷和芳烃化合物复合污染的应用潜能。结果如下：1. 确定了细菌中砷促进芳烃化合物降解的机制；2. 证实了菌株H7是一株异养硝化-好氧反硝化细菌，且菌株H7是优良的氮砷复合污染修复材料并有较广泛的应用价值；3. 开发了能在废水中高效且稳定的去除氮磷能力的复合菌剂——肠杆菌Z1和克雷伯氏菌Z2；4. 探究了肠杆菌Z1高效同步的降解三唑磷(TAP)、甲胺磷(MAP)和碳呋喃(CF)三种芳烃农药的能力，揭示了新的新的微生物降解农药的机制。本研究的成果对于理解微生物中砷和芳烃化合物降解代谢之间的关联机制有重要意义并为砷、芳烃化合物和氮污染修复提供菌种资源。

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