Detection And Community Changes Of Microbial Plankton In Freshwater Environments

Microorganisms are the most abundant, widely spread and diversified entities, which directly affects the freshwater ecosystem function and also directly affects human health. Understanding the microbial community composition and their relationship with environments is a hot topic in the research of freshwater ecosystem. Establishment and optimization of analysis method which can be used to detect aquatic microbes has very important application values and academic significance on microbial ecology.In this paper, flow cytometry (FCM) analysis of microbes was established and optimized, and then applied to detect and enumerate of microbes in water samples from bottled water and water treatment plants. The results shown that1) the bacterial concentrations in most of the samples from bottled water were below103counts/mL. Considering the assimilable organic carbon (AOC) analysis results, it can be conclude that the microbes can not have an explosive growth in the bottled water;2) it was observed that in the drinking water treatment plant the process of activated carbon-membrane ultrafiltration was effective in removal of viruses from the source water;3) investigation of microbes in the sewage water treatment plant illustrated that both bacteria and virus concentrations increased dramatically after the biological processes in wastewater treatment;4) in comparison of traditional microbial detection method, FCM is a rapid, easy, and sensitive tool for understanding the microbial dynamics in aquatic environments.Furthermore, FCM combining with molecular biology techniques (denaturing gradient gel electrophoresis and454pyrosequencing), were employed for the analysis of microbial abundances and microbial community composition. Their relationship with environmental factors were further discussed in river ecosystem which is the most complex aquatic ecosystem. It was conclued that1) in the rivers of Luoxiao mountain area, both the viral and bacterial abundance exhibited a strong negative correlation to elevation, and the bacterial community structure was also observed to by influenced by elevation;2) the abundances of bacterioplankton and virioplankton in the Haihe River were both highest in estuarial area and the abiotic influence on microbial abundance were different in all three areas(urban area, rural area, estuarial area). The level of correlation between abiotic variables and viral abundance was always similar to the relationship between abiotic variables and bacterial abundance.3) the spatial variability pattern in bacterioplankton community composition driven by salinity was stronger than the seasonal variations driven by temperature across river to estuary in the Haihe River;4) bacterioplankton communities separated into urban group and rural group when dataset analyzed within a certain kind of season, indicating that human activities could also be a contributor to microbial community composition.