Hexavalent chromium reducing bacteria: mechanism of reduction and characteristics.

As a common heavy metal, chromium and its compounds are widely used in industrial applications, e.g., leather tanning, electroplating, and in stainless steel, paints and fertilizers. Due to the strong toxicity of Cr(VI), chromium is regarded as a major source of pollution with a serious impact on the environment and biological systems. The disposal of Cr(VI) by biological treatment methods is more favorable than traditional treatment methods because the biological processes are environmentally friendly and cost-efficient. This review describes how bacteria tolerate and reduce Cr(VI) and the effects of some physical and chemical factors on the reduction of Cr(IV). The practical applications for Cr(VI) reduction of bacterial cells are also included in this review.