MOLECULAR APPROACH TO THE MICROBIAL POPULATION IN ACTIVATED SLUDGE IN RELATION WITH THE PERFORMANCE OF WASTEWATER TREATMENT PLANTS

过去污水处理的目标是去除BOD，但现在需要去除氮和磷。随着对处理水平的要求越来越高，我们需要了解微生物种群，并充分利用微生物的力量来去除污染物。在本研究中，我们采用荧光DNA探针可以分析微生物种群结构，用于分析污水处理厂活性污泥中的微生物种群。使用荧光DNA探针的重要一点是，微生物数量可以估计而无需培养。在这项研究中，我们分析了北海道、东京、埼玉和冲绳地区15个污水处理厂的20条处理线上的活性污泥。对每个污水处理厂进行了四次调查；1997年11月，1998年1月，4月和8月。6个探针分别针对(1)真细菌，(2)变形菌α亚类，(3)变形菌β亚类，(4)变形菌γ亚类，(5)革兰氏阳性GC高群，(6)细胞噬菌黄杆菌群。结果表明，在许多污水处理厂中，变形菌门（α - + β - + γ -亚纲）是真细菌的优势类群，而α亚纲和β亚纲在变形菌门中最占优势。微生物种群结构与污水处理厂的位置、水温和营养物去除等条件之间没有显著的关系。但研究发现，规模较小的污水处理厂含有更多的真细菌，而这些细菌没有被本研究中使用的群体特异性探针检测到。在许多污水处理厂，从冬季到夏季，α亚类增加，革兰氏阳性GC高组减少。

The goal of the wastewater treatment used to be the removal of BOD, but nowadays, the removal of nitrogen and phosphorus is required. As the required level of treatment gets higher, we need to understand he microbial population and to make the best of microbial power to remove pollutants. In this research, we employed the fluorescence DNA probes which enables the analysis of microbial population structure for the analysis of microbial population in activated sludge in wastewater treatment plants. One of the important points about using the fluorescent DNA probes is that microbial population can be estimated without cultivation.In this research, we analyzed the activated sludge in 20 treatment lines in 15 wastewater treatment plants in Hokkaido, Tokyo, Saitama, and Okinawa areas. Four surveys were conducted on each of the treatment plants ; November 1997, January, Nay, and August 1998. Six probes were used for the investigation which are targeted at (l)eubacteria, (2) Proteobacteria alpha-subclass, (3) Proteobacteria beta-subclass, (4) Proteobacteria gamma-subclass, (5) Gram positive GC high group, and (6) Cytophaga-Flavobacterium group.It was demonstrated that in many of the wastewater plants, Proteobacteria (alpha- + beta- + gamma-subclasses) were the predominant group of eubacteria, and that alpha-subclass and the beta-subclass are the most predominant in the Proteobacteria. No significant relationships were found between the microbial population structure and the conditions of the wastewater treatment plants, such as location, water temperature, and the nutrient removal. But it was found that the smaller wastewater treatment plants contain more eubacteria which were not detected by the group-specific probes used in this study. In many of the wastewater treatment plants, increase in the alpha-subclass and the decrease in the Gram positive GC high group from winter to summer were observed.