Characterization of microbial community in an activated sludge process treating domestic wastewater using quinone profiles

The dynamics of microbial community structure of activated sludges in a sma ll-scale domestic wastewater treatment process were examined using a novel approach of quinone profiles. The composition and content of quinones in th e activated sludges were analyzed monthly over a period of one year. Mote t han 4 types of ubiquinones and 12 types of menaquinones were observed in th e activated sludges, with the dominant quinones being ubiquinone (UQ) -8, m enaquinone (MK) -7, followed by UQ-10, MK-8 and MK-6. The total quinone con tents in the activated sludges varied from 0.93 to 2.68 mu mol per gram of particle organic carbon. The molar ratio of ubiquinones to menaquinones (UK /MK) changed from 0.38 to 0.98, indicating that anaerobic bacteria dominate d the microbial community of the activated sludges examined. The ratio of U Q/MK varied similar to that of dissolved oxygen in the bulk. The microbial diversity of the activated sludges calculated from the quinone compositions was 13.4-16.8. The diversity of menaquinones was much higher than that of ubiquinones, and increased slightly with increasing temperature. The microo rganisms containing menaquinones appear to be sensitive to the change in te mperature than those containing ubiquinones.