Influence of Calcium Nitrate on Microbial Community Structure of Acidophilic Microorganisms

The influence of different concentrations of calcium nitrate on the growth and activity of acidophilic microorganisms were studied and the microbial community structures were compared by 16S rRNA gene clone library analysis. The addition of Ca (NO3)2has a certain effect on the solution potential, and that the time needed to reach the steady potential were prolonged with the increase of Ca (NO3)2concentration but not obvious when it was above 1.64 g.L-1. It also can be observed that the cell numbers decreased with the increase of Ca (NO3)2concentration which can alter the cell osmolarity, and that the time entering the stationary phase of cell concentration was delayed with the addtion of Ca (NO3)2. With the addition of 0.41g.L-1Ca (NO3)2, the percentage ofLeptospirillum ferriphilumandAcidiphilium cryptumdidn’t have great changes, while the unculturedSulfobacillus sp.,Acidithiobacillus ferrooxidansandAlicyclobacillus toleranswere also detected. With the addition of 2.05 g.L-1Ca (NO3)2or more, theAcidithiobacillus ferrooxidansbecome the dominant bacterium (which accounted for more than 90%).