Microbial community diversity and changes associated with a mine drainage gradient at the Dexing copper mine, China

Water samples were collected from 6 sites in the Dexing copper mine, one of the largest open-cast copper mines in China. Each corresponding habitat exhibited distinct geochemical characteristics allowing us to correlate microbial community structure to environmental conditions. We examined the molecular diversity of 16S rRNA genes in water samples from these sites using a PCR-based cloning approach. A total of 68 operational taxonomic units of 16S rRNA genes from 814 screened clones were obtained. The sequenced clones fell into 5 main phylogenetic divisions. The majority (79.1%) of the clones were affiliated with the Gammaproteobacteria (60%), Acidobacteria (8.8%) and Nitrospira (10.3%). However, these sites showed great differences in composition of microbial communities. Moreover, the environmental variables differed greatly across sites; iron, sulfur and calcium concentrations were the variables significantly correlated to the microbial community composition, indicating that Fe super(2+), S and Ca are possible drivers in shaping microbial community structure. pH was also significantly correlated to microbial community composition at 2 sites.