含挥发性脂肪酸废水中PHA合成菌株的富集机制研究

混合培养合成PHA效率低是剩余污泥资源化所面临的瓶颈问题之一。为解决该问题，我们通过设置适宜生境驯化富集具备高PHA合成能力的菌群。研究发现经挥发性脂肪酸（VFAs）驯化后PHA合成菌株发生特异性富集，其机制有待深入研究。本项目拟以从环氧丙烷废水活性污泥中获得的PHA合成、非PHA合成优势菌株为研究对象，构建不同VFAs驯化富集合成PHA的菌群。通过比较不同菌株对于不同种类VFAs的摄入情况，结合VFAs代谢相关基因表达水平检测，明确PHA合成与非PHA合成菌株间、PHA合成菌株间的互作关系；通过比较丰盛-饥饿两阶段中PHA合成与降解、固氮作用、群感效应等相关基因表达情况，明确固氮作用与PHA合成菌株富集的关系，菌株与环境因素的互作关系；基于上述结果，结合网络分析及通量平衡分析，构建动态代谢网络模型，阐明含VFAs废水中PHA合成菌株的富集机制，为提高混合培养合成PHA的效率提供理论依据。

The low efficiency of PHA synthesis in the mixed culture is one of the bottlenecks to restrict the resource utilization of the residual activated sludge. In order to solve this problem, the residual activated sludge was acclimated, and the bacterial consortia with high PHA-producing ability were enriched through setting up suitable habitat. It was found that after acclimation by the volatile fatty acids (abbreviated as VFAs), there was a specific enrichment of the PHA-producing strains, but its mechanism was not clear. In this project, the dominant PHA-producing and non-PHA-producing strains in the activated sludge to treat the propylene oxide saponification wastewater are taken as the research objects. The bacterial consortia are constructed and acclimated to enrich PHA under the condition of different kinds of VFAs. Through comparing the consumption of different kinds of VFAs among PHA-producing and non-PHA- producing strains, and combined with the detection of the expression level of VFAs metabolism-related genes, the interactions between different strains are clarified. By comparing the expression of genes related to PHA synthesis and degradation, nitrogen fixation and quorum sensing in the stages of feast-famine, the relationship between the nitrogen fixation and enrichment of PHA-producing strains, and the interaction between strains and environmental factors are investigated. Based on the above result, and combined with network analysis and flux balance analysis, a dynamic metabolic network model is established. The ultimate objective of this project is to clarify the mechanism of enrichment of PHA-producing strains in the wastewater containing VFAs, so as to provide a theoretical basis for increasing the efficiency of PHA synthesis in the mixed culture.