Effects Of Microcystis Blooms In Lakes Heavy Metal Content And Form Of Microbial Community Structure

In freshwater ecosystems, Frequent cyanobacterial blooms were caused by water eutrophication, which severely weakened the lake’s ecological function.Bacterial community structure and function are influenced obviously in the cyanobacterial blooms lake. Cyanobacterial can accumulate heavy metals in the processes of the blooms.Heavy metals which are released from Cyanobacterial in the dynamics of blooms will influence the bacterial community structure of freshwater ecosystems. However, bacterial community structure and function are not yet fully understood in the cyanobacterial blooms lake.In this work, microcosm was built to simulate the bacterial community structure influenced by heavy metals. Bacterial community composition, genetic diversity and the main species identification were analysed by polymerase chain reaction, molecular fingerprinting technique-terminal restriction fragment length polymorphism (T-RFLP) and builting a small ribosomal16S rRNA gene libraries.T-RFLP patterns were clustered by UPGMA method, which showed that community structure are significantly different between manipulated group added Cyanobacterial that absorb Cd and other two groups in water.The result come to the same thing in the sediment. In addition, microcosm of different temperature was built and analysis. The result indicated community structure are significantly different between manipulated group added Cyanobacterial that absorb Cd and other two groups in water under the condition of25centigrade. Significant differences of diversity index (Shannon-Wiener index, Simpson index, Pielou index) were found betweent those samples of water and sediments.Totally227partial16S rRNA gene sequences were obtained from four clone libraries. The major bacterial phyla were a-proteobacteria, β-proteobacteria, Synechococcus, Actinobacteria, Bacteriodetes, Planctomycetes, etc. β-Proteobacteria were main edificators in all samples,about59.47%accurately.α-Proteobacteria and Bacteroidetes were14.54%and11.89%respectively. Firmicutes and Actinobacteria were8.37%and1.76%respectively.Other bacterias were seldom. In summary, The results obtained using by T-RFLP and16S rDNA cloning librarlies will help to further understand the changes of the ecosystem structure and the mechanism of functional degradation caused by heavy metals。...