Study On The Correlation Between Water Qualities And Microbial Community Structures In Chagan Lake

Chagan Lake is located in a soda-saline area,making its water alkaline.Moreover,the surrounding farms,stocks,fishery and mining industry make morepollutions.Now,the ecosystem of Chagan Lake undergoes the threat of climatechange and human activities.The relationship between water quantity and ecologyof Chagan Lake had been investigated by the previous studies.But the research onthe water quality and ecology only focused on the macroscopic populations.There is no corresponding work on the distribution and ecological functions of microorganisms has been reported,due to the limited research methods.In this work,a simulation study based on regional water quality characteristics was designed.Besides,a research model based on the continuous monitoring of water quality was coupled with genetic analysis to explore the relationship between water quality and microbial community structure.The work is as follows:1)The relationship between the water quality of Chagan Lake and its microbial communityThe sampling sites were selected from Chagan Lake and the channel from Hadashan.The water quality and high-throughput sequencing technology with statistical analysis were carried out synchronously.The structure and distribution of microbial community were investigated.The unique microbial ecological environment characteristics of Chagan Lake were analyzed.The relationship between species distribution and environmental factors in different regions was analyzed through the correlation analysis between total operational taxonomic unites(OTUs)and environmental factors.PCo A and NMDS analyses suggested that therare taxa were likely to paly important ecological functions.Furthermore,all test samples were assigned into two groups,the lake group and the channel group.The different grouped ways were compared by assigning the sampling sites from entrances and exits into which one of the groups.Weighted and unweighted Uni Frac distance and Welch's t-test were used to calculate and analyze the differences and similarities between the groups.The spatial structure of microbial community and the control factors of water quality factors were studied by combining the Linear Regression and the Principal component analysis.The distribution differences of the microbial communities in the main lake and channel were characterized by Anosim and PLS-DA.The main explanatory factors for the water quality of Chagan Lake are analyzed by RDA analysis and CCA analysis,as well as the regression analysis of MDS and the water quality factors,p H,TDS,DO and EC.2)The interaction relationship between Chagan Lake water quality and characteristic functional genesThe metagenomic sequencing methods were further employed to analyze the characteristic functional genes of Lake Chagan.The international standard biological system gene databases,including KEGG,GO,COG and carbohydrate active enzyme analysis were adopted to annotate the functional genes.The structure,abundance and distribution of functional genes in Chagan Lake were analyzed.The correlation of functional genes between all samples and the feature functional genes of each sample were analyzed by the correlation analysis of all metagenomes at the genus level.The analysis of functional genes in the main differences in distribution between lakes and channels were investigated by phylogenetic trees and distance box plots of the samples.Based on the analysis of functional genes,the most significant feature of Chagan Lake was that a lot of antibiotic resistance genes(ARG)and petroleum hydrocarbon degradation-related functional genes have been annotated.The spatial distribution,co-occurrence analysis,correlation and difference analysis of ARGs and petroleum hydrocarbon degradation-related functional genes were studied.From the result of Spearman analysis,theco-occurrence relationship between ARGs,petroleum hydrocarbon degradation-related functional genes and mobile genetic elements was obtained.3)The driving factors of ecology in Chagan LakeIn the previous studies,the large-scale space-time researches and the laboratory studies were separately carried out in most cases,leading to the lack of mechanism for well explaining the pollution and purification of inland lake.In this work,the capacity of microbial degradation in Chagan Lake was investigated by combing with the water qualities and microbial communities,as well as their functional genes.A series of variates were examined,including irrigation discharge,alkaline condition,indigenous and exogenous microbe interference,sediment and so forth.Biochemical oxygen demand was used as an indicator for evaluating the purification of biodegradable organic matter in water samples.The pollutions of the targeted lake were primarily caused by the co-selection between ARGs and the petroleum hydrocarbon degradation-related microbes.Moreover,the purification period of the targeted lake water could be shorted from two months to 12 days by regulating its microbial communities.The present research strategy can provide valuable insights for exploring the mechanism of pollution and purification in inland lake,and further serve for the local economy and human health.The water quality of Chagan Lake was affected by the farms and stocks and it can be classfied into the class V by the Chinese water quality standard.There are obvious differences in the structure,and function of hydrological connectivity and the microbial communities therein.This study demonstrated that the effects of microbial communities on the degradation of organic contaminations in the inland lake were profound,and for the special Chagan Lake,the accumulation of pollution can be subtracted by the co-selection of petroleum hydrocarbon degradation-related functional genes and ARGs.But the spread of ARGs among indigenous and allochthones bacteria by horizontal gene transfer,which can be the real threat to the balance and stabilization of an aquatic ecosystem.