氨诱导的互营乙酸氧化产甲烷代谢的分子机制与过程控制

The solution of acids accumulation is a breakthrough in the development of efficient anaerobic biological technology. The inhibition of the metabolic process of acetate and more than two carbon VFAs could cause acids accumulation problem. Accumulation of acetate is one of the factors that affect the efficient and stable operation of the anaerobic system. Its solution needs to be accomplished by the metabolism of acetoclastic methanogens, while acetoclastic methanogens grow slowly and are sensitive to environmental factors such as temperature, ammonia concentration and VFAs concentration. This will make it unable to perform its function in the current industrial biogas system with high ammonia concentration. Ammonia-induced syntrophic acetate oxidizing pathway has become a breakthrough point for solving the problem of acetic acid accumulation in the current industrial anaerobic biogas production system, owing to the fact that their functional microorganisms- syntrophic acetate oxidizing bacteria have high ammonia resistance. Based on the above understanding, the project proposes the academic idea of ​​controlling the metabolism of acetic acid to solve the problem of acetate accumulation, basing on revealing the molecular mechanism of the ammonia-induced syntrophic acetate oxidizing pathway. The project will be conducted in three aspects, firstly, the molecular mechanisms of syntrophic acetate oxidizing pathway replacing acetolastic methanogenic pathway in high ammonia systems will be studied, secondly, the migration and transformation mechanism of ammonia itself in the syntrophic acetate oxidizing system will be evaluated, thirdly, the engineering method of acetate metabolism regulation will be explored. These studies would provide technical guidance for the efficient and stable operation of the actual anaerobic systems.

酸积累瓶颈问题的攻克是开发高效厌氧技术的突破口。乙酸和二碳以上VFAs的代谢过程受抑制都会引起酸积累问题。乙酸积累问题作为影响厌氧系统高效稳定运行的重要因素之一，其解决需要借助乙酸型产甲烷菌的代谢来完成，而乙酸型产甲烷菌生长缓慢且对环境因子如温度、氨浓度和VFAs浓度敏感，使其在当前氨浓度较高的工业产沼气系统中无法发挥其功能。氨诱导的互营乙酸氧化途径因其功能菌群互营乙酸氧化菌具有耐高氨特征成为解决当前工业厌氧产沼系统中乙酸积累问题的突破口。基于以上认识，项目提出在氨诱导互营乙酸氧化途径分子学机制揭示的基础上进行乙酸代谢过程控制从而解决乙酸积累问题的学术思想，拟展开高氨系统中互营乙酸氧化途径取代乙酸型产甲烷菌代谢乙酸途径的分子学机制，氨自身在互营乙酸氧化系统中的迁移转化机制，以及乙酸代谢调节的工程学方法三方面的研究，为实际厌氧系统高效稳定运行提供技术指导。

乙酸积累问题作为影响厌氧系统高效稳定运行的重要因素之一，其解决需要借助乙酸型产甲烷菌的代谢来完成，而乙酸型产甲烷菌生长缓慢且对温度、氨浓度和VFAs浓度等环境因子极其敏感。氨诱导的互营乙酸氧化途径因其功能菌群互营乙酸氧化菌具有耐高氨特征成为解决当前工业厌氧产沼系统中乙酸积累问题的突破口。因此，本研究主要从高氨浓度诱导互营乙酸氧化产甲烷途径（SAOB-HM）研究、基于互营乙酸氧化甲烷主导功能菌群强化厌氧共消化工艺效能的实验研究和基于乙酸介导的具有高碳源转化率及高氨耐受性的两相厌氧新工艺开发的三方面展开。研究结果表明，随着厌氧系统中氨浓度的增加，甲烷的产量呈现从抑制到抑制解除的趋势，互营乙酸氧化产甲烷途径的比例逐渐升高，在氨氮浓度为5.0 g/L时，达到93.55%。在有机固废（猪粪与玉米秸秆）厌氧产沼系统中，添加互营乙酸氧化菌（Clostridium ultunense），强化了SAOB-HM途径，在保证沼液肥料性能的同时，解决了厌氧有机物消化氨抑制导致的产气量不高的问题。此外，经过同型产乙酸菌富集后的中温和低温厌氧产酸系统中，有效地实现了碳流向甲酸和乙酸的转化，为后续的产甲烷相提高更加合适的底物。产甲烷系统中互营乙酸氧化途径的转化主要由于功能菌群Acetomicrobiun和Methanothermobacter组成的互营菌群丰度的提升，功能基因的丰度变化表明，乙酰辅酶A合成酶编码基因随着SAOB富集过程逐步升高，且高温体系中更为显著，说明了互营乙酸氧化途径在高温系统中更占优势。本研究通过以互营乙酸氧化产甲烷为研究突破口，解决高氨对厌氧消化效能的抑制，实现了有机物的高效转化，为厌氧生物处理工艺在餐厨垃圾、畜禽粪污等有机物资源化处理领域的大规模应用提供了可能。.