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Abstract
Acid mine drainage (AMD) lake of Xiang Mountain in Anhui Province, China, was characterized by acidic waters (pH around 2.8) containing high concentrations of soluble metals and sulfate. To investigate the function and dynamics of this extreme ecosystem, four water samples were collected from the lake in the fall of 2010. The acidophilic community structure was analyzed by molecular approaches, and bacterial and archaeal clone libraries of 16S rRNA genes were constructed. In contrast to dominance of chemolithotrophic acidophiles in typical AMD environments, autotrophic iron/sulfur-oxidizing bacteria were detected in only one sample with low abundance. Unexpectedly, the Cyanobacteria group was the predominant in all four samples (54.9%−77%). Chemoheterotrophs Acidiphilium and Acidisphaera were also abundant. These two heterotrophic groups contain bacteriochlorophyll that can perform photosynthesis, an advantage to grow and survive in such oligotrophic acidic environments. Only two clone sequences related to Legionella (2.8% of the total clones) were recovered from one sample in sharp contrast to its higher abundance (12.7%) in the summer of 2009. All archaeal sequences were affiliated to the phylum Crenarchaeota. The results of statistical analysis suggested that the water chemistry of the AMD lake controlled microbial composition of the AMD ecosystem.
Acknowledgments
This research was supported by grants from the National Science Foundation of China (40802059, 41030211), the Specialized Research Funds for the Doctoral Program of Higher Education of China (200804911008), and the Fundamental Research Funds for the Central Universities (2010ZD03, 2011YXL035). The authors are grateful to two anonymous reviewers whose comments improved the quality of the manuscript.