Spatiotemporal transition of bacterioplankton diversity in a large shallow hypertrophic freshwater lake, as determined by denaturing gradient gel electrophoresis

Abstract

To describe the variation in bacterioplankton diversity within a large hypertrophic freshwater lake, as well as changes in the diversity that occurred with time, PCR- (denaturing gradient gel electrophoresis) DGGE was utilized to study water samples collected from Lake Taihu in China. To accomplish this, water samples were collected from different locations and during different months. The trophic status of these sampling sites ranged from eutrophic to hypertrophic. Cluster and multidimensional scaling analyses revealed that the temporal transition in the diversity of the bacterio-plankton occurred primarily in response to a cyanobacterial bloom, and that all samples could be divided into normal-bloom, peak-bloom and winter period groups. Spatial differences in the bacterial diversity were also detected among the three sampling sites, with diversity being found to be strongly correlated with the gradient of the trophic status of the three sampling sites. In addition, these temporal and spatial changes could be characterized by several specific DGGE bands. The results were further analyzed by canonical correspondence analysis, which revealed that the bacterioplankton diversity of Lake Taihu was primarily associated with temperature, pH, total nitrogen (TN), total phosphorus (TP) and dissolved oxygen. Of these factors, TN and TP were only shown to be significant influencing factors at Wuxi, which had the highest trophic level.