title: Reduction of chromate (CrO4(2-)) by an enrichment consortium and an isolate of marine sulfate-reducing bacteria.
abstract: An enrichment consortium and an isolate (isolate TKW) of sulfate-reducing bacteria (SRB) have been obtained from metal-contaminated marine sediments of Tokwawan, Hong Kong SAR. These bacteria are capable of reducing highly toxic and soluble hexavalent chromium (Cr6+) enzymatically into less toxic and insoluble trivalent chromium (Cr3+) under anaerobic conditions. The enrichment consortium almost completely (98.5%) reduced 0.6 mM Cr6+ in 168 h and the rate of reduction was 0.5 g (Cr6+) g(protein)(-1)h(-1). In comparison, with Cr6+ as the sole electron acceptor (as a surrogate for SO4(2-)), isolate TKW reduced 94.5% of the initially added Cr6+ (0.36 mM) in 288 h, with the rate of 0.26 g (Cr6+) g(protein)(-1)h(-1). Adsorption by these bacteria was not the major mechanism contributing to the transformation or removal of Cr6+. The biomass and Cr3+ in the cultures increased simultaneously with the reduction of Cr6+. These indigenous SRB might have potential application in bioremediation of metal contaminated sediments.
authors.affiliation: Department of Ecology & Biodiversity, Laboratory of Environmental Toxicology, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, PR China.
authors.forename: K H
authors.initials: KH
authors.lastname: Cheung
authors.forename: Ji-Dong
authors.initials: JD
authors.lastname: Gu
mesh_terms: D000327:Adsorption; D002840:Chromates / Q000737:chemistry* / Q000378:metabolism*; D019015:Geologic Sediments / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction; D011506:Proteins / Q000032:analysis; D013431:Sulfates / Q000737:chemistry; D016999:Sulfur-Reducing Bacteria / Q000302:isolation & purification* / Q000378:metabolism*
chemical_list: D002840:Chromates; D011506:Proteins; D013431:Sulfates