The vertical distribution of bacterial and archaeal communities in the water and sediment of Lake Taihu.

This study was conducted to characterize the vertical distribution of bacterial and archaeal communities in the water and sediment of Lake Taihu, which underwent a change in trophic status from oligotrophic to hypertrophic in last half of the 20th century. The results revealed that the bacterial communities in different layers of sediment sample were very similar, and were related to Alpha-, Beta-, Gamma- and Deltaproteobacteria, Nitrospira, Bacteroidetes, Firmicutes, Gemmatimonadetes, Verrucomicrobia, Chlorobi, Actinobacteria and Acidobacteria. In contrast, the archaeal communities varied greatly with depth. The archaeal communities were primarily related to Euryarchaeota and Crenarchaeota, with methanogenic Archaea accounting for approximately 2-35% of the total Archaea. Additionally, sequences related to putative ammonia-oxidizing Archaea and ammonia-oxidizing Bacteria were detected in different layers of sediment samples. The abundance of Archaea, Bacteria, methanogenic Archaea and Nitrospira was further characterized by real-time PCR.