Metagenomic analysis on seasonal microbial variations of activated sludge from a full-scale wastewater treatment plant over 4 years.

Metagenomic technique was employed to characterize the seasonal dynamics of activated sludge ( AS) communities in a municipal wastewater treatment plant ( WWTP) over 4 years. The results indicated that contrary to E ukaryota (mainly R otifera and N ematoda), abundances of B acteria and A rchaea (mainly E uryarchaeota) were significantly higher in winter than summer. Two-way analysis of variance and canonical correspondence analysis revealed that many functionally important genera followed strong seasonal variation patterns driven by temperature and salinity gradients; among them, two nitrifying bacteria, N itrospira and N itrosomonas, displayed much higher abundances in summer, whereas phosphate-removing genus T etrasphaera, denitrifier P aracoccus and potential human faecal bacteria, i.e. B ifidobacterium, D orea and R uminococcus, showed significantly higher abundances in winter. Particularly, occurrence of dual variation patterns beyond explanation merely by seasonality indicated that multivariables (e.g. dissolved oxygen, sludge retention time, nutrients) participated in shaping AS community structure. However, S EED subsystems annotation showed that functional categories in AS showed no significant difference between summer and winter, indicating that compared with its microbial components, the functional profiles of AS were much more stable. Taken together, our study provides novel insights into the microbial community variations in AS and discloses their correlations with influential factors in WWTPs. [ABSTRACT FROM AUTHOR]