HEXAVALENT-CHROMIUM REDUCTION BY A CHROMATE-RESISTANT BACILLUS SP STRAIN

Bacillus strain QC1-2, isolated from a chromium-polluted zone, was sel ected by its high ability to both tolerate and reduce hexavalent chrom ium [Cr(VI)] to less-toxic trivalent chromium [Cr(III)]. Cell suspensi ons of strain QC1-2 rapidly reduced Cr(VI), in both aerobic and anaero bic conditions, to Cr(III) which remained in the supernatant. Cr(VI) r eduction was dependent on the addition of glucose but sulfate, an inhi bitor of chromate transport, had no effect. Studies with permeabilized cells and cell extracts showed that the Cr(VI) reductase of strain QC 1-2 is a soluble NADH-dependent enzyme.