Composition And Function Of Microbial Community In Different Acid Mine Wastewater

Acid mine drainage（AMD）is characterized by strong acidity and high heavy metal concentration.If it is directly discharged,it will cause serious harm to water bodies,soil and a variety of organisms.Source treatment and end treatment methods have been applied to actual projects,but how to better carry out mine restoration and pollution prevention is still worth thinking about.Acidophilic prokaryotic and eukaryotic microorganisms can promote the production and evolution of acidic wastewater.Therefore,analyzing the composition and ecological functions of acidophilic microbial communities will help to find ways to inhibit the production of acidic wastewater.The acid reservoir PT is located in the dump site and was formed in the 1970s;the acid reservoir TF is about 2.2 km east of the PT and was formed around2013.It was originally a mining pit.This paper uses 16S r RNA amplicon technology to compare and study the seasonal changes of microbial communities in PT and TF acid reservoirs.Based on the binning results of metagenomics,the ecological functions of key bacteria are explored;in addition,metagenomics sequencing analyzed the functional differences of prokaryotic microbial communities in acidic wastewater environments with different pH,and obtained the following results:（1）The pH of PT is 3.01～3.16,and the salinity is as high as 8.6～15.2 g/L;TF is more acidic（pH 2.43～2.75）,and contains high concentrations of Fe（99.3～314 mg/L）.The pH showed a trend of low in summer and high in winter.The autotrophic Ferrovum of PT is the main iron-oxidizing acidophilus in most seasons,and it also contains very rich chemotherapeutic bacteria（48.6±15.9%）.TF’s prokaryotic biodiversity and evenness index are lower than PT.Unlike PT,chemoautotrophic iron oxidizing bacteria（71.7±25.4%）have a dominant position in all seasons of TF.（2）Bin9 and Bin21 belonging to Ferrovum in PT can fix CO₂through the Calvin cycle and are the main primary producers in the community.They also have the gene encoding iron oxidase and can perform ferrous iron oxidation.In addition,Bin9 has the nitrogenase gene and has the ability to fix N₂.Bin2 and Bin39 belong to Acidiphilium.Bin39 can decompose glucose through the ED pathway and has the function of organic oxidation;Bin2 has Calvin cycle and SOX complex,which plays the role of fixing CO₂and sulfur oxide.（3）There are high concentrations of SO₄^2-and Fe³⁺in NS,SXL and SX with pH less than2.6,and the lowest ion concentration in DSN（pH 4.80）with the weakest acidity.In the most acidic NS（pH 2.20）autotrophic iron-sulfur oxidizing bacteria are the dominant bacteria.As the pH rises,the dominance of the chemoautotrophic bacteria lost,and the proportion and types of heterotrophic bacteria increase significantly,and even common bacterial genera in neutral environment appear.Acidithiobacillus in NS plays the main role of fixing CO₂,fixing N₂,sulfur oxide and ferrous iron.The function of carbon fixing,sulfur oxide and iron oxide in SXL（pH2.61）,which is slightly acidic,is mainly performed by Ferrovum,while in A1 with higher pH（pH 3.00）Acidiphilium can perform carbon fixation,nitrogen fixation and sulfur oxidation.