Study On Characteristics Of Microbial Community And Its Environmental Correlation In Different Nutrition Types Lakes Of Yunnan Plateau

Microorganisms are an important part of the lake ecosystem.As a unique habitat,the Yunnan Plateau Lake Ecosystem has different microbial community structures from different trophic lakes.The relation between microbial community composition and environmental factors is close.It is of great significance for maintaining the balance of the lake ecosystem,protecting and managing the lake to carry out a comprehensive systematic analysis of the microbial community structure of lake water and sediments and their relations with environmental factors,revealing the differences in microbial community structure from different trophic lakes.This study takes the sediments of Yunnan Dianchi Lake as the research object,and a high-throughput sequencing method is used to explore a suitable extraction method for genomic DNA from Lake Sediments from Yunnan Plateau.This study also takes the poor nutrition Fuxian Lake and the eutrophic Xingyun Lake in Yunnan Plateau as the research objects.Based on high-throughput sequencing technology,it analyses the seasonal changes of microbial community structure characteristics in the water and sediments from two different trophic lakes and the correlation between environmental factors and microbial communities.At the same time,the species diversity of cyanobacteria phylum in two lakes in different periods was analyzed.The main research results are as follows:1.By comparing 11 methods for extracting genomic DNA from sediments from Dianchi Lake,the DNA obtained by MOBIO DNeasy Power Soil kit extraction method is transparent and soluble.As a result,the average OD260/OD280 is 1.825;the average DNA concentration is 18.205 ng/L;the DNA purity is high and the yield is high.In the analysis of amplicon sequencing,the MOBIO DNeasy Power Soil kit extraction method has high species richness,uniformity and species diversity,which is the best suitable DNA extraction method for lake sediments in Yunnan plateau.2.There are obvious differences in environmental factors between the poor nutrition Fuxian Lake and the eutrophic Xingyun Lake.The content of dissolved oxygen,chlorophyll a,chemical oxygen demand,nitrogen and phosphorus in Xingyun Lake is higher than that in Fuxian Lake.There is a certain relation between environmental factors.Temperature and dissolved oxygen are inversely proportional in high,flat and withered water periods.Potassium in sediment is inversely proportional to calcium and magnesium content.According to RDA analysis,temperature,dissolved oxygen,nitrogen and phosphorus are found to be the main environmental factors affecting the changes of microbial community structure in Fuxian Lake and Xingyun Lake in different periods.Among them,T,DO,PO₄^3--P,NH₄⁺-N are significant environmental factors affecting the changes of Prokaryotic microbes and Eukaryotic microbes community structure in the water of the two lakes.TP,PO₄^3--P are significant environmental factors affecting the changes of prokaryotic microbes and eukaryotic microbes community structure in the sediments from the two lakes.COD_Mn,TP and p H are significant environmental factors affecting the changes of Archaea community structure in the water of the two lakes,while K,Ca,Na,Mg and NO₃^--N are significant environmental factors affecting the changes of Archaea community structure in the sediments from the two lakes.3.There are obvious differences in the microbial community structure between the water and sediment from the two lakes originated in plateau.There is more microbial species in the sediment than in the water,especially Prokaryotic microbe species.The two lakes have different richness of microbial species during high water period,flat water period and withered water period.There is more unique species in the period with the largest number of species.The structure,richness and evenness of microbial community in water and sediment of the two lakes in different periods are significantly different,which are related to the trophic type,spatial heterogeneity and seasonal variation of the lakes.There are obvious differences between the dominant species of Prokaryotic microbes and Eukaryotic microbes,and Archaea in the water and sediment of these two lakes of different trophic types,Fuxian Lake and Xingyun Lake.In Prokaryotic microbes,Proteobacteria and Bacteroidetes are the dominant species in the sediment of the two lakes.Cyanobacteria and Proteobacteria are the dominant species in the water of Xingyun Lake,while Proteobacteria,Actinobacteria and Bacteroidetes are the dominant species in the water of Fuxian Lake.In Eukaryotic microbes,Cryptomonadales and Ochrophyta are the dominant species in the water of Xingyun Lake,while Cryptomonadales,Fucophyta and Ciliophora are the dominant species in the sediment in each period.Cryptomonadales,Arthropoda and Dinoflagellata are the dominant species in the water of Fuxian Lake,while Annelida,Cryptomonadales and Gastrotricha are the dominant species in the sediment in each period.In Archaea,during the high water period,Methanothrix in the water and sediment of Xingyun Lake and Nitrososphaera of Thaumarchaeota in the water and sediment of Fuxian Lake are the dominant species.Methanosarcina of Euryarchaeota is the dominant species in two lakes water and sediment during the flat water period.The species diversity of Cyanobacteria in Fuxian Lake and Xingyun Lake is obviously different in different water periods.The species of Cyanobacteria in Fuxian Lake is diverse,while that in Xingyun Lake is relatively single.The genera with high diversity of Cyanobacteria in the two lakes are Synechococcus,leptolyngbya and pseudoanabaena.