Correlating microbial diversity patterns with geochemistry in an extreme and heterogeneous mine tailings environment. Microbial communities in the SMC tailings

Recent molecular surveys have advanced our understanding of the forces shaping the large-scale ecological ranges of microbes in Earth’s extreme habitats, such as hot springs and acid mine drainage. Lacking, however, are extensive and representative sequence analyses of microbial communities at specific sites to resolve the local diversity of these extraordinary organisms and how communities are shaped by the harsh environmental conditions. We have applied a 16S rRNA gene-targeted 454 pyrosequencing approach to explore the phylogenetic differentiation of microbial communities from 90 randomly taken surface samples in a massive copper tailings impoundment generating acidic drainage, and coupled these variations in community composition with geochemical parameters to reveal ecological interactions in this extreme environment. Our data revealed that overall microbial diversity estimates and relative abundances of most dominant lineages were significantly correlated with pH and microbial community composition showed the consistent shifts along the pH gradient, indicating that different taxa were involved in the different acidification stages of mine tailings. Furthermore, the effect of pH on shaping phylogenetic structure within specific lineages was also clearly evident, although the phylogenetic differentiations within the Alphaproteobacteria, Deltaproteobacteria and Firmicutes were attributed to variations in ferric and ferrous iron concentrations.