Analysis on functions of micro-animals in the detritus food webs of biological wastewater treatment systems.

本研究旨在阐明污水生物处理系统中微生物生态系统与其净化功能之间的关系。从日本典型的生活污水就地生物处理设施Johkasou系统中分离到一些细菌，并通过16 SrRNA序列对分离的细菌进行鉴定。一些适当的细菌（粘质沙雷氏菌等）为研究微生物生态系统在污水处理过程中的作用，同时，利用T-RFLP技术对污水处理系统中复杂的微生物生态系统进行了分析。实验结果表明，Philodina sp.具有良好的过滤效果和混凝效果，可用于制备高透明水。此外，我们还得到了在嗜热菌捕食条件下有机碳的矿化速度比在细菌单一培养条件下快的结果。此外，总的DOC和TOC的减少量增加的纤毛虫T.嗜热菌的存在。在以细菌为微宇宙系统的混合培养体系中，具有简单碎屑食物网结构。另一方面，对一个简单的捕食者-食饵模型的数值分析得出了与实验结果相矛盾的结果。也就是说，我们的实验结果强烈地表明，捕食者如原生动物和/或后生动物的存在增加了细菌分解有机物的活性，因为细菌和原生动物之间简单的捕食者-猎物相互作用只会导致作为有机物分解者的细菌种群减少。

In this study, it aimed to clarify the relations between the microbial ecosystems in biological wastewater treatment systems and its purification functions for waste water. Some bacteria were isolated from Johkasou systems, which are typical on-site biological domestic wastewater treatment facilities in Japan, and the isolated bacteria were identified by sequences of 16SrRNA. Some appropriate bacteria (Serratia marcescens etc.) were selected, in order to study on the function of microbial ecosystems for the wastewater treatment process. Moreover, it was shown that the T-RFLP method was a useful molecular biological tool for the analysis on complex microbial ecosystems in wastewater treatment systems.The mixed culture experiments with aquatic rotatoria, Philodina sp. and isolated bacteria from some Johkasous were performed. It was shown that Philodina sp. was very effective to make high transparent water by the filtration effect and the coagulation effect of Philodina sp.. Moreover, we obtained the result that mineralization of organic carbon under the condition of predation for bacteria by Philodina sp was faster than it under the monoculture condition of bacteria. Also, total amount of decreases of DOC and TOC was enhanced by the existence of Ciliata T.thermophila. in the mixed culture system with bacteria as a microcosm system with a simple detritus food web structure. On the other hand, the numerical analysis of a simple predator-prey model drew out the result of contradiction to our experimental results. That is, our experimental results strongly suggest that existence of predator such as protozoan and/or metazoan increase the activity of bacteria for decomposition of organic matter, because the simple predator prey interaction between bacteria and protozoa only causes decrease of bacterial population as decomposer of organic matter.