Characterization of iron and manganese minerals and their associated microbiota in mine sites

Different environmental conditions induce precipitation of different minerals and their associated microorganisms may vary. Therefore, mine precipitates from various environmental conditions were sampled and their associated microbiota analyzed through metagenomic DNA sequencing. Under the different environmental conditions, Fe and Mn minerals, including ferrihydrite, schwertmannite, goethite, birnessite, and Mn-substituted d-FeOOH (d-(Fe1-x, Mnx)OOH) were found. The Fe and Mn minerals were enriched with toxic metals including As, Cd, Ni and Zn, indicating they can act as scavengers of toxic metals in mine streams. Under acidic conditions, Acidobacteria was dominant phylum and Gallionella (iron oxidizing bacteria) was the predominant genus in these iron rich environments. Manganese oxidizing bacteria, Hyphomicrobium, was found in birnessite forming environments. Leptolyngbya within Cyanobacteria was found in Fe and Mn oxidizing environments, and might contribute to Fe and Mn oxidation through the production of molecular oxygen. Understanding characteristics of mine precipitates and associated microbes helps in developing strategies for the management of contaminated mine waters.