Bacterial Community Structure And Its Relationship With Environmental Factors In Ecological Restoration Huixian Wetland

Huixian wetland which is known as the largest karst peak lake-type wetland in the Li River Basin in China has poor ecological stability.Bacteria are important driving factors for the migration and transformation of nutrients and energy cycle in the ecosystems.They respond rapidly to environmental changes,so they are often used to characterize environmental quality.However,there are few studies on the diversity of bacterial community in Huixian Karst wetland.In order to analyze the pollution situation of Huixian karst wetland and reveal the relationship between bacterial community structure and environmental factors,the water and sediment quality of 12 samples were measured and the bacterial community structure,diversity and abundance were investigated by the high-throughput sequencing technology from March2018 to February 2019.The main results are as follows:（1）The comprehensive pollution index of water and sediment showed that Huixian wetland water is heavily polluted in spring,and it is severely polluted in the other three seasons.The main over-standard indicators are TP,TN and DO.The sediments are heavily polluted in all four seasons.It indicates that the main pollutants in Huixian Wetland are nitrogen,phosphorus nutrients and oxygen-consuming compounds,and the eutrophication is serious.The sources of pollution are mainly point source pollution such as dock domestic sewage and non-point source pollution such as agricultural water.（2）Proteobacteria is the absolutely dominant phylum in the wetland,which is widely distributed in water,sediment and plant rhizosphere.Other dominant phyla are Bacteroidetes,Actinobacteria,Chloroflexi,and Acidobacteria.Among them,Proteobacteria participates in the cycle of carbon,nitrogen,phosphorus and sulfur;Chloroflexi and Bacteroidetes participate in the carbon cycle.（3）The genus has a high level of bacterial diversity,and there are a large number of unidentified and uncultured bacteria,indicating that there are many potential new species in the wetland.There were differences in community structure among different types of samples,but overall,the main dominant genera and their ecological functions were as follows:Polynucleobacter,unidentified_Rhodocyclaceae,Limnohabitans,unidentified_Gamma-proteobacteria,Stenotrophomonas,unidentified_Burkholderiaceae and Sphingomonas are presumed to be involved in the nitrogen cycle;unidentified_Deltaproteobacteria is presumed to be involved in the cycle of carbon,phosphorus and sulfur;Pseudarcicella,Flavobacterium,Fluviicola and unidentified_Dehalococcoidia are presumed to participate in the carbon cycle.（4）Analysis of environmental factors of the bacterial community showed that the environmental factors have great influence on the diversity and abundance of bacterial community in water are pH,COD_Cr,Cl^-,SO₄^2-,NO₃^--N and COD_Cr.TN,NO₃^--N and NO₂^--N are the major factors affecting the diversity and abundance of sediment and plant rhizosphere bacterial communities.And the dbRDA analysis shows that TP and NH₄⁺-N have a major impact on the bacterial community structure of Huixian wetland.