Discovering Novel Iron Oxidizing Microorganisms as A Control Method for Problematic Sulfur Reducing Bacteria

Sulfate-reducing bacteria produce hydrogen sulfide (H₂S) as an end-product of their metabolism, which is a toxic gas that contributes to biosouring in oil reservoirs and natural gas systems. The intermediates of nitrate-reduction, nitrite (NO₂^-) and nitric oxide (NO), are potent inhibitors of sulfate reduction.  The addition of ferrous iron (Fe(II)) to nitrate reducing cultures leads to the production of higher concentrations of NO₂^- and NO and  we have proposed that microorganisms which oxidize iron coupled to nitrate reduction may be effective at inhibiting sulfate reduction in oil reservoirs and other industrial settings.  It is therefore important to search for and isolate novel microbes from various environments that are similar to these conditions.  For example, a few organisms which can carry out nitrate-dependent iron oxidation have been isolated from high salt and high temperature environments such as oil reservoirs. Using samples taken from oil wells in Alaska and areas of interest we hope to isolate new species of thermophiles and halophiles that oxidize iron coupled to nitrate reduction.  Ultimately, we will test the ability of our isolates to inhibit sulfate-reduction under oil reservoir conditions.