Study On The Changes Of Microbial Community In Drinking Water Source Reservoirs In Shanghai

The water source reservoir shoulders the important task of providing human drinking water,and the microorganisms in the water body play an important role in the ecology and water quality safety of the water body,especially the water source.According to the monitoring of Shanghai water supplies department in recent years,the water quality of this water source has shown a trend of nutritionalization^[4].As it is located in the Yangtze estuary,which belongs to the ecological crisscross region between Marine and freshwater habitats,its waters have a special ecological environment^[5].Taken from the water of the Yangtze river with high nutrient salt level,the water source is shallow and located in the temperate zone,where the water stays for a long time and the flow rate is small,which provides the appropriate environmental conditions for the algal proliferation^[6].Therefore,algal proliferation has been one of the major problems since the water source was built.The secondary metabolites from algae and some microorganisms are also an important cause of water odor^[7].It is reported that in recent years,the water body in this water source has a"bad smell"phenomenon,which greatly affects the taste of drinking water.This study water samples of different season 5 sampling point as the research object,based on 16 s rRNA genes and ITS Illumina Miseq high-throughput sequencing technology research,the water source of the microbial community diversity,seasonal changes,the microflora composition,community structure and function,etc.,and combined with environmental factors to analyze ITS water quality influence on microbial community,explore potential links between microbial community structure and environment.The main conclusions are as follows:in May and July,the total number of species was high,but the biodiversity decreased.The physicochemical parameters of environmental factors indicate that the water quality of the water source has an eutrophication trend during this period,and there is algal proliferation in the water source,which leads to the decrease of microbial diversity.The variation trend of algae in water source area was dominated by Cyanobacteria in summer and diatoms in autumn and winter.In general,the abundance of Cyanobacteria and Actinobacteria shows the opposite trend,The variation trend of Actinomyces and Ilumatobacter abundance was consistent,which was opposite to that of Bacillariophyta.The higher the nutrient concentration was,the higher the relative abundance of?-Proteobacteria was.Some algae-soluble bacteria were also found in the samples,which play a key role in the decline and degradation of algae.Outside the reservoir,Proteobacteria,Acidobacteria and Nitrospirae decreased in abundance after entering the water mouth,and these bacteria declined after entering the reservoir,while Cyanobacteria,Verrucomicrobia and Planctomycete enriched and increased in flow along the reservoir.The elevation of Cyanobacteria in the downstream of the reservoir proves that eutrophication in the reservoir has been enhanced.Reservoir internal and abundance of higher eukaryotic algae Bacillariophyta?diatom?,Chlorophyta?green algae?,Cryptomonadaceae,outside the reservoir did not find the eukaryotic algae,which further confirmed that the reservoir and the eutrophication tendency is likely to be the inevitable link;RDA environmental factor analysis showed that permanganate index,ammonia nitrogen and nitric nitrogen were the main factors affecting the microbial community structure in water supply area.