Chromium(VI)-resistant yeast isolated from a sewage treatment plant receiving tannery wastes

Abstract

A Cr(VI)-resistant yeast, designated strain DBVPG 6502, was isolated from a sewage treatment plant receiving wastes from tannery industries in Italy. The strain was tentatively identified as a species of Candida based on morphological and physiological analyses. This strain was highly resistant to Cr(VI) when compared with eight other yeast species, growing at Cr(VI) concentrations of up to 500 micrograms/ml (10 mM). This resistance was constitutive. The Cr(VI)-resistant yeast did not reduce Cr(VI) to Cr(III) species under aerobic conditions. The yeast showed very little accumulation of Cr(VI). Consequently, the mechanism of resistance of the yeast to Cr(VI) appears to involve reduced accumulation of Cr, as has been shown in Cr(VI)-resistant bacteria.