基于二维稳定C-Cl同位素解析顺-1,2-二氯乙烯好氧代谢机理

Aerobic metabolism of cis-1,2-DCE as sole carbon and energy source has significant advantages such as high metabolic rate, low oxygen demand, no additional auxiliary substrate and no generated toxic metabolites, representing its potential for field application. However, the community structure of cDCE assimilating bacteria, dominant species and the aerobic metabolic pathway of cDCE are not known yet in recent studies. The project aims to obtain cDCE assimilating bacteria through multi-selecting bacteria sources and optimizing enrichment conditions on the basis of previous studies, and to identify the dominant species. The community structure of cDCE assimilating bacteria will be further investigated to reveal its response to different enrichment environment. The optimal conditions on cDCE mineralization by cDCE assimilating bacteria will be proposed. Furthermore, the project will demonstrate the potential of cDCE assimilating bacteria for hypoxic cDCE mineralization and for aerobic cometabolism of BTEX, respectively. In addition, the dual stable C-Cl isotope fractionation during the aerobic cDCE mineralization will be investigated to infer the bond cleavage in the rate-limiting reaction, and to estimate the relative extent of cDCE biodegradation shared over aerobic metabolism and anaerobic reductive dechlorination in hypoxic condition. Based on the results of above studies, the project will evaluate the aerobic metabolism of cDCE and reveal its mechanism. This will provide important empirical and theoretical evidences to further identify and quantify the aerobic metabolism or anaerobic reductive dechlorination in hypoxic zone of contaminated field sites.

以cDCE为唯一碳源和能源的好氧代谢过程具有代谢速率高、需氧量低、无需辅助底物添加、无有毒代谢中间产物产生等优点，在实际场地修复应用中前景十分可观。然而，优势cDCE同化菌群落结构和cDCE的好氧代谢转化途径尚不明确。本项目拟在前人研究基础上，通过丰富菌源和优化富集条件，获得cDCE同化混合菌。鉴定优势菌群，揭示cDCE同化菌群落结构与富集环境的响应关系。确定cDCE好氧代谢的最优条件，明确优势混合菌对cDCE的超低氧代谢潜力及对苯系物的好氧共代谢能力。分析C和Cl同位素在cDCE好氧代谢中的分馏及演变趋势，推断限速反应中化学键的断裂方式，估算超低氧下好氧代谢和厌氧还原脱氯两种竞争转化途径降解cDCE的相对贡献份额比。基于上述研究结果，揭示cDCE的好氧代谢机理，以期为判识和量化实际污染场地超低氧区cDCE的好氧代谢/厌氧还原脱氯过程提供重要的科学理论依据。

以cDCE 为唯一碳源和能源的好氧代谢过程具有代谢速率高、需氧量低、无需辅助底物添加、无有毒代谢中间产物产生等优点，在实际场地修复应用中前景十分可观。然而，优势 cDCE 同化菌群落结构和 cDCE 的好氧代谢转化途径尚不明确。因此，本项目选取沈阳和北京某有机氯乙烯污染场地的多个地下水样和土壤样品为菌源，开展了以cDCE为唯一碳源和能源的好氧矿化菌群的富集和培养研究。通过一年多的探索，最终获得了以cDCE为唯一碳源和能源的好氧矿化菌群，并确定了cDCE好氧代谢混合菌生长的最优条件。同时，通过宏基因组测序方法，揭示了cDCE好氧代谢菌群落结构特征及其演变规律，并进一步鉴定出优势菌群，确定其进化关系，丰富了cDCE好氧代谢菌群落的生物学信息。随后，考察了cDCE好氧代谢菌在低氧条件下的好氧代谢特性，为揭示cDCE的好氧代谢机理提供重要的科学理论依据。

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