抄録
We investigated the population dynamics of nitrifying bacteria in autotrophic nitrifying biofilms by using Real-Time PCR and fluorescent in situ hybridization (FISH). Primers and TaqMan probe specific to genus Nitrospira including uncultured Nitrospira sp. in the biofilms were newly designed and applied to the biofilms. The populations of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) determined by Real-Time PCR during steady-state condition were 1.2×108cells/cm2 and 3.5×108cells/cm2, respectively. The population dynamics of nitrifying bacteria corresponded with the reactor performance and the development of nitrifying bacteria in the biofilms determined by FISH. Real-Time PCR revealed that specific growth rates of uncultured Nitrospira sp. were 0.021h-1 in the suspended enrichment culture and 0.014h-1 in the biofilms. Average specific growth rates of both nitrifying bacteria during the steady-state condition in the biofilms were significantly lower than that during the log phase, might suggest that metabolic pathway of nitrifying bacteria in the biofilms was different in the log and stationary phase. We speculated that Real-Time PCR was powerful and suitable technique for understanding of microbial population dynamics in the complex microbial communities.
