KCS

Dissimilatory iron- and sulfate-reducing Bacteria (DIRB and DSRB) are common subsurface microorganisms as iron and sulfate are abundant in many natural environments. DIRB and DSRB couple the oxidation of organic carbon or H₂ to the reduction of iron and sulfate, which plays important roles in cycling of carbon, metals, and sulfur in the subsurface environment. DIRB and DSRB have also profound implications for the fate and transport of organic and inorganic contaminants in aquatic and terrestrial systems. Subsurface contamination by heavy metals or organic contaminants is a big concern for human health and environmental protection. In situ bioremediation is one option for reducing levels of contaminants. Introducing suitable substrates into the subsurface can stimulate the growth of iron and/or sulfate reducing microorganisms which often reduce contaminants either directly or by the production of reactive Fe(II) and sulfur species. In this presentation, we will discuss 1) the effects of several electron donors (i.e., acetate, lactate, and glucose) on the enrichment of specific communities capable of reducing iron and sulfate and 2) the effects of sulfate reduction on Fe^III (hydr)oxide (i.e., ferrihydrite, lepidocrocite, and goethite) reduction and microbial community development.