Reduction of chromate by marine bacillus megaterium TKW3

K. H. Cheung, H. Y. Lai, Ji Dong Gu

Research output: Contribution to journalConference articlepeer-review


Hexavalent chromium (Cr6+) is an important corrosion inhibitor and is also highly toxic pollutant, which can be detoxified and precipitated through reduction to Cr3+. Bacillus megaterium TKW3 isolated from contaminated sediments was capable of reducing Cr6+ in concomitance with metalloids (Se4+, Se6+ and As5+). Notwithstanding the approximately 50% inhibition, it is firstly reported that bacteria reduced Cr6+ and Se4+ [to elemental Se] simultaneously. No significant difference was observed among electron donors (glucose, maltose and mannitol) on Cr6+ reduction of B. megaterium TKW3. The process was mediated by a novel aerobic membrane-associated reductase with Cr6+induced expression, and specific reductive activity of 0.220 nmol (Cr6+) mg-1 (protein) min-1. Respiratory inhibitor NaN3 did not obstruct the reductase activity. Transmission electron microscopy with energy dispersive X-ray analyzer confirmed the aggregation and accumulation of Cr along intracellular membrane region. 2-Dimensional gel electrophoresis analysis of the proteins expressed by B. megaterium TKW3 exposed to Cr6+ vs. that without Cr6+ in culture media revealed positive expression of specific proteins. Further identification of the amino acid sequence of this novel reductase would facilitate understanding of its enzymatic action on Cr6+ reduction and bioremediation.

Original languageEnglish
Pages (from-to)65211-652110
Number of pages586900
JournalNACE - International Corrosion Conference Series
StatePublished - 2006
Externally publishedYes
EventCorrosion 2006 - Orlando, FL, United States
Duration: 10 Sep 200614 Sep 2006


  • Bacillus megaterium
  • Chromate reductase
  • Corrosion inhibitor
  • Heavy metals
  • Proteomics


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