title: Respirometric characterization of aerobic sulfide, thiosulfate and elemental sulfur oxidation by S-oxidizing biomass.
abstract: Respirometry was used to reveal the mechanisms involved in aerobic biological sulfide oxidation and to characterize the kinetics and stoichiometry of a microbial culture obtained from a desulfurizing biotrickling filter. Physical-chemical processes such as stripping and chemical oxidation of hydrogen sulfide were characterized since they contributed significantly to the conversions observed in respirometric tests. Mass transfer coefficient for hydrogen sulfide and the kinetic parameters for chemical oxidation of sulfide with oxygen were estimated. The stoichiometry of the process was determined and the different steps in the sulfide oxidation process were identified. The conversion scheme proposed includes intermediate production of elemental sulfur and thiosulfate and the subsequent oxidation of both compounds to sulfate. A kinetic model describing each of the reactions observed during sulfide oxidation was calibrated and validated. The product selectivity was found to be independent of the dissolved oxygen to hydrogen sulfide concentration ratio in the medium at sulfide concentrations ranging from 3 to 30 mg S L(-1). Sulfide was preferentially consumed (SOURmax = 49.2 mg DO g(-1) VSS min(-1)) and oxidized to elemental sulfur at dissolved oxygen concentrations above 0.8 mg DO L(-1). Substrate inhibition of sulfide oxidation was observed (K(i,S(2-))= 42.4 mg S L(-1)). Intracellular sulfur accumulation also affected negatively the sulfide oxidation rate. The maximum fraction of elemental sulfur accumulated inside cells was estimated (25.6% w/w) and a shrinking particle equation was included in the kinetic model to describe elemental sulfur oxidation. The microbial diversity obtained through pyrosequencing analysis revealed that Thiothrix sp. was the main species present in the culture (>95%).
authors.affiliation: GENOCOV Research Group, Department of Chemical, Biological and Environmental Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
authors.forename: Mabel
authors.initials: M
authors.lastname: Mora
authors.affiliation: GENOCOV Research Group, Department of Chemical, Biological and Environmental Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
authors.forename: Luis R
authors.initials: LR
authors.lastname: López
authors.affiliation: GENOCOV Research Group, Department of Chemical, Biological and Environmental Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Lafuente
authors.affiliation: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
authors.forename: Julio
authors.initials: J
authors.lastname: Pérez
authors.affiliation: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
authors.forename: Robbert
authors.initials: R
authors.lastname: Kleerebezem
authors.affiliation: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
authors.forename: Mark C M
authors.initials: MC
authors.lastname: van Loosdrecht
authors.affiliation: Department of Mining Engineering and Natural Resources, Universitat Politècnica de Catalunya, Bases de Manresa 61-73, 08240 Manresa, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Gamisans
authors.affiliation: GENOCOV Research Group, Department of Chemical, Biological and Environmental Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain. Electronic address: david.gabriel@uab.cat.
authors.forename: David
authors.initials: D
authors.lastname: Gabriel
mesh_terms: D000332:Aerobiosis; D056804:Biofuels; D018533:Biomass; D005374:Filtration / Q000379:methods; D007700:Kinetics; D010084:Oxidation-Reduction; D013440:Sulfides / Q000737:chemistry / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism*; D013885:Thiosulfates / Q000378:metabolism*; D053525:Thiothrix / Q000302:isolation & purification*
chemical_list: D056804:Biofuels; D013440:Sulfides; D013885:Thiosulfates; D013455:Sulfur
keywords: Elemental sulfur; Kinetic and mechanistic analysis; Respirometry; Sulfide; Sulfide oxidizing bacteria; Thiothrix sp.