Seasonal Variation Of Microbial Community And Metagenomics Analysis In Different Acid Mine Drainage Lakes

Acid mine drainage?AMD?is a kind of mining wastewater with very low pH?<3.5?and high concentration of metal ions due to long-term exposure of sulfide minerals to the surface,interacting with water,oxygen,and microorganisms.Acidophilic microorganisms play an important catalytic role in the formation of AMD.This paper studied the seasonal variation of acidophilic community in two AMD lakes?PT and TF?with similar geographical locations but different physical and chemical properties.The effects of physical and chemical factors on community composition,and the use of metagenomics methods to analyze the differences in the functional acidophilic communities in two AMD lakes.The specific research results are:?1?There are obvious differences in the physical and chemical properties of the two acid reservoirs.Lake PT formed in the 1970s is weak in acidity with an annual average pH of 3.16±0.08,while lake TF,recently formed has strong acidity,and the annual average pH is 2.80±0.16.The main anion of the two AMD lakes is SO₄^2-,?12125.72±3406.54 mg/L?in PT,which was twice as much?5301.74±2683.39 mg/L?in TF.Due to many years of accumulation,main metals?aluminum,calcium,and magnesium?and mineralization in the PT are much higher than TF.The main metal ions of the two acid reservoirs reached their highest concentrations in summer,and chlorophyll a in lake PT reached a peak?587.24?g/L?in winter samples.?2?The main acidophilic bacteria in the two acid reservoirs are Ferrovum and Acidiphilium,across the four seasons.The prokaryotic diversity of lake PT is higher than that of TF,and heterotrophic bacteria are more abundant,including Acidiphilium,Legionella,Acidisoma,and Acidisphaera.However,TF has a higher proportion of autotrophic bacteria,mainly Ferrovum,Leptospirillum and Acidithiobacillus.?3?Statistical analysis showed that the concentration of Fe²⁺was positively correlated with the number of OTU and Shannon diversity index,indicating that Fe²⁺is the main environmental factor driving the distribution of acidophilic community in AMD.RDA analysis also shows iron,calcium,pH,and Fe²⁺are the physicochemical factors that have the greatest impact on microbial community structure.?4?The structure of the eukaryotic community is relatively simple.Lake PT is mainly populated by photosynthetic algae such as Ochromonas and Chlamydomonas which causes winter blooms.Lake TF has a more diverse eukaryotic community than PT,mainly dominated by Chrysonebula.Other algae such as Klebsormidium and Chlamydomonas,and protozoa such as Oxytricha and Sminthurides.?5?The heat shock protein?Hsp?,fatty acid desaturase?DesA?and DnaK and other chaperone proteins detected in TF have a high abundance,which plays an important role in the resistance of cells to extreme acidity;a high proportion of carbonic anhydrase in TF?CynT?helps autotrophic organisms to supplement inorganic carbon in strong acid and low CO₂ conditions.The concentration of SO₄^2-in PT is high,so there are abundant genes involved in sulfur metabolism,and thiosulfate sulfurtransferase?PspE?is responsible either in nutrition or energy and play an important role in survival competition under restrictive conditions.