The Study On Microbial Diversity And Environmental Factors Correlation In Gehu Lake

Six sampling sites were set and samples were collected from the surface of Gehu lake seasonally from December 2016 to September 2017,in order to investigate the correlation between microbial diversity and environmental factors.The physical and chemical properties of the samples were determined during the same period at the sampling sites.The microbial isolation and culture techniques were used to count the number of microorganisms and identify the species of microbes.The community composition and diversity of microbes were also analysed in the present study.The relationship between microbial community structure and environment factors was investigated to provide basic data for the protection and sustainable development of ecological environment of Gehu Lake.The physical and chemical indicators in each sampling site were monitored,the result of which showed that the water temperature presented obvious seasonal variations due to the influence of atmospheric temperature.The water was alkaline with the average pH to be 8.23.The average value of dissolved oxygen was 6.48 mg/L,negatively correlated with water temperature.The average values of chlorophyll a,ammonia nitrogen concentration,the total nitrogen concentration,the total phosphorus concentration,and the average value of the Permanganate index concentration were0.013 mg/L,0.40 mg/L,2.65 mg/L,0.13 mg/L,0.13 mg/L,respectively.There were significant correlations among WT,NH₃-N,TN,TP and COD _Mn.The total phosphorus concentration,chlorophyll a and total nitrogen concentrationin Gehu Lake were higher due to the nitrogen and phosphorus pollution.As is shown in the preliminary studies of Gehu Lake,the number of bacteria was more that of actinomycetes,and the number of actinomycetes was also more that of fungi.A total of 740 microorganisms were isolated and they were assigned to 60 genus.There were 494 bacteria assigned to37 genus,195 actinomycetes assigned to 10genus,and 51 fungi assigned to 13 genera.The relative abundance of each microorganism varies greatly among seasons and sampling sites,and the species composition of microbial communities at each sampling site varied greatly.The bacterial community and actinomycete community had relatively small differences,and the fungal community composition was relatively different.The difference of microbial species composition at each sampling site decreased in autumn.Species assigned to genera Pseudomonas,Acinetobacter,Streptomyces,Nocardia,and Penicillium played an important role in the seasonal variation and spatial distribution of the composition of microbial community in Gegu Lake.The difference between the Shannon-Wiener index and the Pielou index of the microorganisms at each sampling site was small,and the Margalef index was different.The bacterial community structure was relatively stable and species richness was high.Pearson correlation coefficient was used to analyze the relationship between microbial number,diversity index and environmental factors.Redundancy analysis and canonical correspondence analysis methods were used to analyze the relationship between the species distribution and environmental variables in Gehu Lake.The results show that:the seasonal variation and spatial distribution of the quantity,community composition and diversity of the microorganisms in Gegu Lake were affected by the synergistic effects of various environmental factors and showed some differences due to different environments.The key factors affecting the distribution of bacterial species were WT,DO,COD _Mnn and TN.Additionally,WT was the key factor affecting the number and distribution of actinomycetes,and DO was the key factor affecting the distribution of fungi.The NH₃-N,TN and TP were the main environmental factors that affected the distribution of dominant species.The WT,pH,DO and COD _Mnn were the major water environmental factors affecting microbial diversity,and the Shannon-Wiener index of microbes had close correlations with the Pielou evenness index and Margalef richness index.