John Hottenstein

Soil, Water, and Environmental Science

Characterization of microbial iron and sulfur oxidation pathways promoting acidification during mine tailing revegetation
Adverse effects from mining activity in the western US have left a lasting legacy to human and ecological health decades after mining activity has ended. Although such sites can potentially be reclaimed, acid mine drainage and heavy metal mobilization can inhibit plant growth and limit broader reclamation efforts. Bacteria and archaea, specifically those who obtain energy from iron and sulfur oxidation, are the primary generators of acid mine drainage which inhibits plant growth establishment. At the Iron King Mine and Humboldt Smelter Superfund (IKMHSS) site, the microbial iron and sulfur oxidizing activity is carried out by distinct populations of microbes along pH (2 to 7) and oxygen availability (aerobe to anaerobe) gradients. To better understand how the iron and sulfur oxidizing activity responds to revegetation efforts, my research aims to study the iron and sulfur oxidizing community through a comprehensive understanding of the iron and sulfur oxidizing bacteria, through iTag 16S rDNA identification, as occupying an ecological niche within the soil microbiome. First, a novel culturing method designed to mimic the soil environment will be used to isolate microbial communities that are involved in sulfur and iron oxidation both independently and together. Second, archived samples across six years from the phytostabilization field study conducted at the IKMHSS will be used to study the microbial community and its changes over time. The changes in similarity between laboratory microbial communities and the field study microbial community can then be linked to changes in soil biogeochemical properties. The results of this research can be used to identify better-targeted reclamation strategies that utilize natural processes and rely less on costly soil amendments to provide long-term success while protecting human and ecological health.