Reduction of chromate (CrO42-) by an enrichment consortium and an isolate of marine sulfate-reducing bacteria

K. H. Cheung, Ji Dong Gu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

134 Scopus citations


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 SO42-), 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.

Original languageEnglish
Pages (from-to)1523-1529
Number of pages7
Issue number9
StatePublished - Sep 2003
Externally publishedYes


  • Bioremediation
  • Hexavalent chromium
  • Marine enrichment consortium
  • Metal reduction
  • Sole electron acceptor
  • Sulfate-reducing bacteria


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