Microbial Community Structure And Function In Daihai Sediments Feature Research

Daihai was an important economic development and ecological protection area in the Yellow River Basin.Microorganisms were an integral part of the ecological environment.It played an irreplaceable role in the material cycle and ecological regulation of the ecosystem.At the same time,the ecological environment has always influenced the microbial community structure.Microorganisms in sediments were susceptible to the influence of natural environmental elements and anthropogenic disturbances.At present,our knowledge of the microbial communities in the sediments of the Daihai Lake is relatively limited in terms of the patterns of change under spatial differences.In this study,we used macro-genome sequencing technology to study the structure and functional distribution characteristics of microbial communities in the sediments of the Daihai Lake and analyzed the status of the Daihai Lake sediments,which is important for the environmental management and pollution control of the Daihai Lake.The sediment physicochemical indexes showed a more obvious spatial distribution characteristic.The analysis results for sediment physicochemical indexes showed that the spatial level distribution of total nitrogen and nitrate nitrogen were more similar,the agricultural land in the northern part of the lake area was more dense,the surface source pollution of agricultural land was serious,and a large amount of underutilized pesticides and fertilizers entered the water body in the form of surface runoff through leaching and seepage,which brought a great exogenous nitrogen load to the area.The redox state of the sediment has a great influenced on the distribution of ammonia nitrogen.Generally speaking,the higher the redox potential of the sediment,the higher the oxidation capacity of the sediment,which is instead unfavorable to the accumulation of ammonia nitrogen in the sediment.The weak reduction zone in the lake core area,which promoted the accumulation and fugacity of ammonia nitrogen in the sediment,thus formed an area with high ammonia nitrogen content.The eastern lake area is the steepest part of the Daihai coast slope,there were several large rivers such as the Clover River,these rivers were flowing through the vast lakeside pastures,livestock manure has a rich source of phosphorus,the river brought these sources of phosphorus into the lake,thus formed a high value area of total phosphorus.The total nitrogen content of surface sediment in Daihai ranged from 1632.18-2975.64 mg/kg with a mean value of 2251.32 mg/kg;ammonia nitrogen content ranged from 89.50-316.85 mg/kg with a mean value of 178.47 mg/kg;nitrate nitrogen content was low,ranged from 5.08-8.31 mg/kg with a mean value of 6.44 mg/kg;the total phosphorus content ranged from789.28-998.32 mg/kg,with an average value of 906.26 mg/kg.The total nitrogen content of the sediment in the Daihai Lake area has exceeded the lowest level of ecotoxic effect standard,and posed a great threat to the ecological environment of the lake.The results of microbial community structure analysis showed that the dominant phyla of microorganisms in the Daihai Lake sediments were Proteobacteria(49.69%～65.18%),Chloroflexi(21.52%～38.98%),and Nitrospira phylum(3.39%～4.19%),Lactobacillus phylum(1.11%～3.54%).The dominant bacteria class of microorganisms in Daihai sediments were Betaproteobacteria(20.66%～31.27%),C.Class(14.84%～21.31%),Caldilinea(6.89%～14.55%),Anaerobic Proteobacteria(Anaerolineae,9.76%～12.65%).The dominant genus of microorganisms in Daihai sediments were Thiobacillus(20.66%～31.27%),Gammaproteobacteria(13.37%～18.25%),Caldilinea(6.89%～14.84%),Anaerobic(7.35%～14.84%).Thiobacillus is the dominant species in the sediment of Daihai,which can greatly reduce the amount of reducing sulfide in the sediment and then reduce the contaminant content in the sediment.Thiobacillus may be an important microbial resource for the treatment of physical and chemical index pollution.The results of microbial function analysis showed that the dominant functions of microorganisms in Daihai sediments were Carbohydrate metabolism(11.05%～11.31%),Amino acid metabolism(9.81%～10.05%),and Energy metabolism(8.96%～9.12%),Metabolism of cofactors and vitamins(6.44%～6.59%),Membrane transport(5.63%～5.21%),and Nucleotide metabolism(4.71%～5.05%).There was a negative correlation between microbial function and physicochemical indexes in the sediments of Daihai.The sediment microbial community in Daihai was a complex community composed of many microorganisms,which is an important representative of the ecosystem of the Yellow River Basin.The microorganisms in the sediments of Daihai Lake affected the changes of their physical and chemical indexes,and different types of sediment microorganisms have various response laws to the environment.The effective use of the effect of microorganisms in the sediments of Daihai Lake on the physical and chemical indexes can provide coping strategies for the treatment of the sediments of Daihai Lake in the future.