Dissimilatory Iron-Reducing Bacteria Can Influence the Reduction of Carbon Tetrachloride by Iron Metal

Little is known about the long-term performance of zerovalent iron (Fe 0 ) subsurface barriers. Groundwater exposure induces corrosion processes that can passivate the Fe 0 surface and decrease barrier reaction rates. We present evidence that dissimilatory iron-reducing bacteria (DIRB) can stimulate the rate of carbon tetrachloride (CT) transformation in the presence of corroded iron. The DIRB, Shewanella alga BrY, adhered to the corroded Fe surfaces that showed little or no capacity to transform CT. The addition of BrY to these systems with decreased CT transformation rates resulted in increased ferrous iron concentrations and increased CT transformation to chloroform (CF). The results suggest that DIRB can have an influence on the long-term performance of Fe 0 barriers.