title: Sulfide oxidation under chemolithoautotrophic denitrifying conditions.
abstract: Chemolithoautotrophic denitrifying microorganisms oxidize reduced inorganic sulfur compounds coupled to the reduction of nitrate as an electron acceptor. These denitrifiers can be applied to the removal of nitrogen and/or sulfur contamination from wastewater, groundwater, and gaseous streams. This study investigated the physiology and kinetics of chemolithotrophic denitrification by an enrichment culture utilizing hydrogen sulfide, elemental sulfur, or thiosulfate as electron donor. Complete oxidation of sulfide to sulfate was observed when nitrate was supplemented at concentrations equal or exceeding the stoichiometric requirement. In contrast, sulfide was only partially oxidized to elemental sulfur when nitrate concentrations were limiting. Sulfide was found to inhibit chemolithotrophic sulfoxidation, decreasing rates by approximately 21-fold when the sulfide concentration increased from 2.5 to 10.0 mM, respectively. Addition of low levels of acetate (0.5 mM) enhanced denitrification and sulfate formation, suggesting that acetate was utilized as a carbon source by chemolithotrophic denitrifiers. The results of this study indicate the potential of chemolithotrophic denitrification for the removal of hydrogen sulfide. The sulfide/nitrate ratio can be used to control the fate of sulfide oxidation to either elemental sulfur or sulfate.
authors.affiliation: Department of Chemical and Environmental Engineering, University of Arizona, Tucson, Arizona 85721-0011, USA.
authors.forename: Ricardo Beristain
authors.initials: RB
authors.lastname: Cardoso
authors.forename: Reyes
authors.initials: R
authors.lastname: Sierra-Alvarez
authors.forename: Pieter
authors.initials: P
authors.lastname: Rowlette
authors.forename: Elias Razo
authors.initials: ER
authors.lastname: Flores
authors.forename: Jorge
authors.initials: J
authors.lastname: Gómez
authors.forename: Jim A
authors.initials: JA
authors.lastname: Field
mesh_terms: D000085:Acetates / Q000737:chemistry; D052818:Autotrophic Processes; D001681:Biological Assay; D001709:Biotechnology / Q000379:methods*; D002621:Chemistry / Q000379:methods; D006862:Hydrogen Sulfide / Q000494:pharmacology; D007700:Kinetics; D008956:Models, Chemical; D009566:Nitrates / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D013440:Sulfides / Q000737:chemistry*; D013455:Sulfur / Q000494:pharmacology; D013816:Thermodynamics; D013885:Thiosulfates / Q000737:chemistry / Q000494:pharmacology; D014865:Waste Disposal, Fluid / Q000379:methods
chemical_list: D000085:Acetates; D009566:Nitrates; D013440:Sulfides; D013885:Thiosulfates; D013455:Sulfur; D009584:Nitrogen; D010100:Oxygen; D006862:Hydrogen Sulfide