Abstract:

A bacterial 16S rDNA gene clone library was constructed to investigate the bacterial diversity of active sludge in Gaobeidian Wastewater Treatment Plant, Beijing. The results indicated that, the bacterial diversity of active sludge was very high, and the clones could be divided into 5 different groups. The dominant bacterial community was proteobacteria, which accounted for 76.7%. The order of predominancy of bacterial communities are as follows: the βproteobacteria (39.8%), the uncultured bacteria (22.33%)， the γproteobacteria (20.15%), the αproteobacteria (6.79%) and the δproteobacteria (4.85%). The Nitrosomonaslike and Nitrospiralike bacteria, such as Nitrosomonas sp. (1.94%) and uncultured Nitrospirae bacterium(11.65%) were also found, which have played important roles in oxidation of ammonia and nitrite in the system. However, they were only of a small amount because of their slow growth and less competitive advantage than heterotrophic bacteria. Denitrifying bacteria like Thauera sp. was at a high percentage, and it suggests that the active sludge has a stronge denitrifying effect. Roseomonas sp. was also found in the clone library, which could be related to the degradation of organophosphorus pesticide.

Key words:

active sludge; microbial molecular ecology; 16S rDNA clone library; bacterial diversity; Gaobeidian Wastewater Treatment Plant