絮状污泥颗粒化过程中细胞膜形态结构变化规律及功能解析

Extracellular polymeric substance (EPS) is the foundation in aerobic granulation process, and the formation of EPS is always induced by the transfer of biological information. Based on the understanding of transmembrane movement activated by first messenger and second messenger, it is generally assumed that there is close relation between the variations of components, morphology, structure and function of cell membrane and cell signal transduction process. According to the results of preliminary experiments from grey correlation degree analysis, EPS is recognized as the most important factor in aerobic granulation process and it is usually formed by the regulation and control of relevant gene in cell signal transduction, such as first messenger and second messenger. In order to clarify the formation process of aerobic granular sludge, this project is going to investigate the cell membrane of floc sludge and analyze the cell membrance function in such process by means of the study on membrane permeability and membrane potential. The formation mechanism of aerobic granular sludge can be preliminary drawn depended on the analysis of cell membrane characteristics and function, which is helpful to promote the application and supply the theory and technology of aerobic granular sludge.

胞外聚合物是活性污泥颗粒化的物质基础，而污泥微生物胞外聚合物的形成过程则由环境刺激下的信息传递启动。基于对第一信使和第二信使在絮状污泥颗粒化过程中存在跨膜运动现象的认识，认为细胞膜的组成、形态结构和功能变化，可能与第一信使和第二信使参与完成的细胞信号转导过程密切相关。由预实验结果可知，基于灰色关联度理论，由第一信使和第二信使参与完成的细胞信号转导过程，通过其对相关基因的调节与控制而代谢产生的胞外聚合物是絮状污泥颗粒化的最重要因素。为进一步阐明絮状污泥颗粒化机理，本申请项目拟以污泥微生物细胞的细胞膜为切入点，分析污泥颗粒化过程中细胞膜通透性、膜电位与细胞膜组分、比例的变化规律，揭示细胞膜在絮状污泥颗粒化过程中的功能作用，通过对细胞膜性质和细胞膜功能规律的分析，初步阐明基于细胞膜功能解析的絮状污泥颗粒化机理，为推动好氧颗粒污泥技术的产业化应用提供理论依据和技术支持。

现阶段好氧颗粒污泥技术存在形成机理尚未明确，从第二信使和细胞膜角度开展研究，为好氧颗粒污泥形成机理假说建立提供理论依据。絮状污泥颗粒化过程中，胞外聚合物快速增长且增量主要以蛋白质为主，蛋白质主要以TB-PN的形式增加。第二信使环二鸟苷酸呈现先升高后降低的变化规律。好氧颗粒污泥胞外聚合物含量受重金属胁迫而明显下降，主要以蛋白质含量下降为主，多糖含量小幅降低。重金属可以将环二鸟苷酸分解为两分子GMP，从而丧失信息传递的功能，低含量的环二鸟苷酸是造成好氧颗粒污泥失稳现象的重要因素。环二鸟苷酸对好氧颗粒污泥的形成和维持稳定性均具有重要作用，其影响主要体现在对EPS分泌的直接干预。第二信使信息传递的同时细胞膜通透性显著上升，并在好氧颗粒污泥初步成型时达到最高，胞内和胞外物质中有机组分相似性也随之升高。随着重金属毒性累积，微生物会逐步降低细胞膜通透性，细胞通过控制正负离子传输的离子通道维持胞内和胞外电位稳定，使细胞膜电位最终维持不变。