Pathways of sulfide oxidation by haloalkaliphilic bacteria in limited-oxygen gas lift bioreactors.
Physicochemical processes, such as the Lo-cat and Amine-Claus process, are commonly used to remove hydrogen sulfide from hydrocarbon gas streams such as landfill gas, natural gas, and synthesis gas. Biodesulfurization offers environmental advantages, but still requires optimization and more insight in the reaction pathways and kinetics. We carried out experiments with gas lift bioreactors inoculated with haloalkaliphilic sulfide-oxidizing bacteria. At oxygen-limiting levels, that is, below an O(2)/H(2)S mole ratio of 1, sulfide was oxidized to elemental sulfur and sulfate. We propose that the bacteria reduce NAD(+) without direct transfer of electrons to oxygen and that this is most likely the main route for oxidizing sulfide to elemental sulfur which is subsequently oxidized to sulfate in oxygen-limited bioreactors. We call this pathway the limited oxygen route (LOR). Biomass growth under these conditions is significantly lower than at higher oxygen levels. These findings emphasize the importance of accurate process control. This work also identifies a need for studies exploring similar pathways in other sulfide oxidizers such as Thiobacillus bacteria.
Systems and Control group, Wageningen University, Bornse Weilanden 9, P.O. Box 17, 6700 AA Wageningen, The Netherlands. johannes.klok@wur.nl
Johannes B M
JB
Klok
Pim L F
PL
van den Bosch
Cees J N
CJ
Buisman
Alfons J M
AJ
Stams
Karel J
KJ
Keesman
Albert J H
AJ
Janssen
D000468:Alkalies / Q000378:metabolism; D001419:Bacteria / Q000254:growth & development / Q000378:metabolism*; D001673:Biodegradation, Environmental; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology*; D052918:Environmental Restoration and Remediation / Q000295:instrumentation* / Q000379:methods*; D006219:Halogens / Q000378:metabolism; D006862:Hydrogen Sulfide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D053858:Metabolic Networks and Pathways; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D010101:Oxygen Consumption; D013045:Species Specificity; D013440:Sulfides / Q000378:metabolism*; D013855:Thiobacillus / Q000378:metabolism
D000468:Alkalies; D006219:Halogens; D013440:Sulfides; D010100:Oxygen; D006862:Hydrogen Sulfide