Population dynamics of the ammonia-oxidizing bacteria in a full-scale municipal wastewater treatment facility

The purpose of this study was to examine the ammonia oxidizing bacterial (AOB) communities from a full-scale municipal wastewater treatment plant, and to relate these analyses to treatment efficiency. Although almost complete nitrification was observed for extended periods of the year, nitrification efficiency decreased to about 60-80% during December through March. Substantial changes in the AOB community structure were detected using a nested PCR-DGGE approach. Quantification of Nitrosomonas oligotropha-like bacterial populations by competitive quantitative PCR targeting amoA gene fragments revealed that these populations varied more than eightfold throughout the year. Statistical analysis revealed a weak correlation between the quantity of N. oligotropha-like populations and nitrification efficiency, suggesting that these quantification of these bacteria would be useful for monitoring nitrification in wastewater treatment bioreactors.