Study on Microbial Community Structure of Immersed Biofilter in Urban River

Immersed biofiler was applied to purify the river water by increasing of microorganism quantity in the system. In order to analysis the water purification process, the denaturing gradient gel electrophoresis (DGGE) and real-time PCR technology were used to analysis the microbial community and the superior strains of the system. DGGE pattern showed that there has been a stable community structure on the 14^th day (Z1) and single microbial community in March (Z5) in enormous water diversion period, finally, stable microbial community structure were formed in mature biofilm period (Z6~Z8). Homology analysis of superior strains indicated there was bacteria-eating zooplankton gene (Epistylis urceolatao) in mature biofilm, forming a good food chain to promote the decomposition of pollutants in the river. The number of total bacteria and β-proteobacteria AOB during the different period in biofilm was detected by real-time PCR. The results showed that quantity of total bacteria and β-proteobacteria AOB were stable around 10¹⁰ and 10⁹ cells/L water, respectively, and their ratio was around 6%-8% in mature biofilm period.