Genetic Diversity Of Bacterioplankton In Fresh Water

Bacterioplankton is very abundant in aquatic ecosystems, and it plays an important role in freshwater and marine environments. In this paper, we investigated the diversity and bacterioplankton community composition in three freshwater lakes with different levels of nutrition (Lake Xiaquanchi which was poor nutrition, Lake Liangzi which was moderate nutrition and Lake Yue which was mild eutrophication) of Wuhan and three plateau lakes (Lake Bitahai which was poor nutrition, Lake Yangzonghai which was moderate nutrition and Lake Qilu which was moderate eutrophication) in Yunnan Province. The16S rDNA library of each lake was constructed including extraction of total bacterial DNA, amplification of16S rDNA and cloning into E. coli.100clones respectively from Lake Liangzi, Lake Xiaquanchi and Lake Yue were picked for unidirectional sequencing, and more than90sequences of each lake were obtained. The number of OTUs in the three lakes was40,31and27respectively. The Coverage of the three libraries was75.34%,83.82%and83.53%, respectively. The diversity of bacterioplankton in Lake Langzi is higher than in the other two lakes, while the diversity of bacterioplankton in Lake Yue is lower than in Lake Liangzi and Lake Xiaquanch. β-proteobacteria and a-proteobacteria were dominant groups in Lake Liangzi. Bacteroidetes, r-proteobacteria and a-proteobacteria were dominant groups in Lake Xiaquanchi, while actinobacteria as the dominant group in Lake Yue. For Lake Bitahai, Lake Yangzonghai and Lake Qilu,50clones from each lake were picked for sequencing, and finally obtained more than40sequences for each lake. The number of OTUs in the three lakes was13,14and12, respectively. The dominant bacterial group in Lake Bitahai was bacteroidetes. r-Proteobacteria was the dominant bacterial group in Lake Yangzonghai. β-proteobacteria was the dominant bacterial group in Lake Qilu. We compared diversity of bacterioplankton in the three lakes, and found that the diversity of bacterioplankton in Lake Yangzong is higher than in the other two lakes, while the diversity of bacterioplankton in Lake Qilu is lower than in Lake Yangzong and Lake Bitahai.