厌氧消化系统互营丙酸氧化菌群结构和代谢特征及抑制响应

As a wastewaters treatment technology, anaerobic digestion is generally considered as a process with low stability, sensitive to various inhibitors and difficult to control. The basic reason is the lack of in-depth and systematic understanding of the microbial mechanism of anaerobic digestion. The syntrophic oxidization of metabolic intermediates, kinds of low chain fatty acids, is considered to be the bottleneck of anaerobic digestion process. Propionate is one of the important intermediates which is the most difficult to be degraded and the most likely to be accumulated during anaerobic digestion. Due to the propionate oxidizing bacteria are difficult to be pure cultivated; the understanding of them is very limited so far. The study of the structure and metabolism of syntrophic propionate oxidizing flora and their inhibitor response mechanism in the microbial community level is very important for the stable operation and the efficiency improvement of the anaerobic digestion system. Based on stable isotope probing and metaomics techniques, this project will systematically study the structure, function and metabolic characteristics of syntrophic propionate oxidizing flora and reveal their response law to various typical inhibitors during anaerobic digestion. In addition, the possibility of regulating and controlling the syntrophic propionate oxidizing flora under various inhibition conditions will also be studied to enhance the controllability, stability, and efficiency of anaerobic digestion. The achievements of the project will not only complement and improve the basic microbiology of syntrophic fatty acid oxidization in anaerobic digestion but also provide microbiological guidance to the directional controlling of microbial community and the development of novel anaerobic digestion process.

厌氧消化被认为是稳定性不高、易受各种抑制物影响且不易控制的废水处理技术，其根本原因是对厌氧消化微生物学机理尚缺乏深入和系统的了解。中间代谢产物短链脂肪酸的互营降解被认为是厌氧消化过程的瓶颈步骤。丙酸是重要的中间代谢产物，最难被降解也最易被积累。由于丙酸氧化菌的难培养性，到目前为止对它们的认识非常有限。在微生物群落水平研究互营丙酸氧化菌群结构和代谢及抑制物响应机制，对厌氧消化系统的稳定运行和效率提升非常重要。本项目将基于稳定同位素标记和宏组学手段，系统解析厌氧消化过程互营丙酸氧化菌群的结构、功能和代谢特征，揭示它们对各种典型抑制物的响应规律，探讨对常见抑制条件下的互营丙酸氧化菌群进行调控的可能性，提升厌氧消化的可控性、稳定性、和效率。研究成果将补充和完善厌氧消化过程互营脂肪酸氧化相关微生物学基础，为厌氧消化微生物菌群的定向调控及厌氧消化新工艺的研发提供微生物学指导。

厌氧消化产沼气是有机废水/废物处理和清洁能源生产的主要技术，但厌氧消化过程易受各种因素影响，稳定性和消化效率都有待提升。由于对厌氧消化微生物学机理缺乏系统认知，目前尚难以对其进行及时及有效的精准调控，多凭经验进行操作控制。产氢产乙酸阶段是厌氧消化过程中间代谢产物挥发性脂肪酸被进一步氧化分解的过程，由于热力学不可行性，需要产氢产乙酸细菌和产甲烷菌的互营代谢才能完成，是厌氧消化的核心步骤，也是调控的关键目标。丙酸是厌氧消化过程的主要中间代谢产物，丙酸氧化以及其代谢产物乙酸的进一步氧化分解对厌氧消化产甲烷过程至关重要。由于丙酸以及乙酸互营菌的难培养性，对这些互营菌如何参与和影响产甲烷代谢的机理还不清楚，不了解它们对抑制因子胁迫的响应机制，无法建立有效调控技术。本研究通过构建以乙酸和丙酸为唯一碳源的中温和高温连续厌氧消化体系，成功富集了获得了乙酸和丙酸互营氧化微生物群落，通过16S扩增子高通量测序，阐明了乙酸和丙酸降解群落结构特征；通过13C乙酸和13C丙酸对微生物群落进行稳定同位素标记，挖掘了系统分类地位多样的潜在的新型乙酸和丙酸氧化菌；通过宏基因组和宏转录组技术揭示了新型互营乙酸氧化菌和互营丙酸氧化菌代谢特征及其和产甲烷菌的互营特性；基于批次抑制实验和连续抑制实验，结合高通量测序，揭示了氨等典型抑制物对乙酸和丙酸降解菌群结构和功能的影响机制；对处理实际废水的厌氧消化系统，基于微生物强化试验，证明了外源乙酸和丙酸降解菌群强化对受抑制厌氧微生物菌群进行调控的可能性。本项目研究成果完善和深化了对互营乙酸和丙酸氧化菌以及其和产甲烷菌互营机制的认知，阐明了互营脂肪酸氧化菌群对环境胁迫的响应机制，以及互营脂肪酸氧化菌群强化对厌氧消化系统的有效性，为厌氧消化菌群调控提供了微生物理论基础和技术路径。