Eutrophication Of Shallow Lakes Poly Ball Blue Bacterial Community Structure And Genetic Diversity Research

Lake eutrophication has become the most widespread problem concerned in the water environment. With the rapid development of population, industry and agriculture, China’s lake eutrophication problems have become more serious in the last two decades and triggered a series of environmental and ecological problems. Because of the excess primary productivity of shallow lakes of eutrophication, the study of the Synechococcus’ community structure and genetic diversity in shallow lakes of eutrophication will help us to understand the niche, community composition and ecological function of Synechococcus in shallow lakes of eutrophication. Synechococcus is widely distributed in the oceans and lakes, occupies an important position in the primary productivity, and has a great significance to the stability and diversity of the oceans and lakes’ ecosystems. Our understanding about Synechococcus is severely restricted by traditional isolation and pure culture methodologies. However, important progresses have been made on the community composition and genetic diversity of Synechococcus since the application of modern molecular biology techniques.Comparative studies on the community composition and genetic diversity of Synechococcus in different seasons and Shallow lakes of eutrophication will have important ecological and environmental significance. In this study, we applied terminal restriction fragment length polymorphism (T-RFLP) to analyze the community composition and diversity of Synechococcus at different Spatial and temporal changes in four Shallow lakes of eutrophication (Lake Dianchi, Lake Xingyun, Lake Chaohu and Lake Taihu). By building16S+ITS rDNA clone libraries and ITS rDNA clone libraries to research the genetic diversity and evolutionary relationship of Synechococcus.By analyzing the abundance and diversity indexes of Synechococcus, we found significant differences in different seasons and Shallow lakes of eutrophication. Synechococcus community composition and similarity analysis showed significant differences in different seasons and Shallow lakes of eutrophication. These results fully demonstrated that Shallow lakes of eutrophication had Spatial and temporal variations in abundance, community composition and diversity of Synechococcus. Abundance, community composition and diversity of Synechococcus’ temporal variations mainly due to the impact of water temperature changes, Spatial variations caused by the impact of geographical isolation. By comparing the community composition similarity of Synechococcus, there are differences in particle-attach samples and free-living samples. Because when lake water had a long Stagnation period, particles and their microenvironment differed, caused selection pressure to make increased differences between particle-attach samples and free-living samples of Synechococcus. Multivariate statistical analysis showed that Zooplankton number, TOC and Temperature were related to (p<0.05) to dynamics of Synechococcus community composition in particle-associated bacterial samples, while Conductivity, TN and PO4-P were related (p<0.05) with variations of Synechococcus community composition in free-living bacterial samples.There were three16S+ITS rDNA clone libraries and three ITS rDNA clone libraries were builded in Lake Dianchi and Lake Chaohu. We sequenced185sequences, and they were divided into52OTUs. We found High ITS diversities of Synechococcus in Lake Dianchi and Lake Chaohu. The Lake Chaohu’s genetic diversity of Synechococcus was much higher than the Lake Dianchi’s. The proposed new Synechococcus clusters’ sequences account for64%the total sequences. The clone libraries’ results show that the genetic diversity of Synechococcus has spatial differences, those differences mainly due to the geographical isolation that could result in parallel evolution or horizontal gene transfer.