Factors affecting chromium(VI) reduction by Thiobacillus ferrooxidans

Abstract

The ability of Thiobacillus ferrooxidans cultures to reduce chromium(VI) to chromium(III) was evaluated under different conditions. In T. ferrooxidans cultures with sulphur as energy source, the capacity for chromium(VI) reduction was related to the generation of sulphur compounds (sulphite, thiosulphate and polythionates) with high reducing power. In contrast with other chromium(VI)-reducing microorganisms, T. ferrooxidans showed higher chromium(VI) reduction at low pH. The reduction of chromium(VI) also increased with the age of the culture. A T. ferrooxidans cells were capable of growing under anaerobic conditions with chromium(VI) as the terminal-electron acceptor.