Bacterioplankton community structure in a eutrophic lake in relation to water chemistry

Bacteria are thought to be closely involved in the biogeochemical cycling of the nutrient elements in freshwater ecosystems. In contrast, little is known about the relationship between the bacterial community structure and the environmental factors. In order to investigate the spatial variety of bacteriplankton community structure in Lake Xuanwu (Nanjing, China) and the effects of water quality on the microbial community composition, denaturing gradient gel electrophoresis (DGGE) and multivariate statistical analysis were carried out. Eight major factors of water quality such as total organic carbon, ammonium, nitrate, nitrite, total nitrogen, total phosphorus, dissolved oxygen and pH were measured in eight different samples. The significant differences of water characteristics among different sites were revealed by principal component analysis. Results of multidimensional scaling analysis demonstrated that lake water quality played a crucial role in bacterioplankton community composition. Canonical correspondence analysis was carried out to infer the relationship between environmental variables and bacterial community structure. An influence of total nitrogen, ammonium and pH on the bacterial community was observed. The sequencing analysis results of excised DGGE bands revealed that Bacteroidetes and Proteobacteria were the dominant bacterial groups in Lake Xuanwu.