Acidithobacillus ferrooxidans (A. ferrooxidans) is a gram-negative, acidophilic and chemolithotropic bacterium that utilizes oxidation of ferrous ions, hydrogen and reduced inorganic sulfur compounds, such as H2S, as sources of energy. Sulfur oxidation in A. ferroxidans is catalyzed by the Sulfide Quinone Reductase (SQR) enzyme system. The initial step of the SQR reaction is the oxidation of sulfide to elemental sulfur or to the less-toxic polysulfide. SQR can eliminate the accumulation and persistence of H2S in waters and reservoirs contaminated with sulfur-reducing bacteria (SRB). H2S causes reservoir souring, corrosion problems, and presents a danger to oilfield personnel because of its inherent toxicity. SQR does not destroy the SRBs present in the system, but it does catalytically attack the H2S and H2S precursors produced by SRBs. As an enzyme, SQR is an environmentally compliant, sustainable, and catalytic solution to the growing H2S problem. The Sulfide Quinone Reductase enzyme (Bio-molecular scavenger-BMS) was evaluated for its efficacy as an H2S mitigation strategy. The evaluation showed that the BMS could convert H2S from different sources in liquid and gaseous phases in to nontoxic polysulfide. The studies also showed that the BMS-based H2S mitigation reactions did not cause corrosion, and the formulations are compatible with oilfield metals, plastics and elastomers.

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