Interactions of chromium with microorganisms and plants

Chromium is a highly toxic non-essential metal for microorganisms and plant s. Due to its widespread industrial use, chromium (Cr) has become a serious pollutant in diverse environmental settings. The hexavalent form of the me tal, Cr(VI), is considered a more toxic species than the relatively innocuo us and less mobile Cr(III) form. The presence of Cr in the environment has selected microbial and plant variants able to tolerate high levels of Cr co mpounds. The diverse Cr-resistance mechanisms displayed by microorganisms, acid probably by plants, include biosorption. diminished accumulation, prec ipitation, reduction of Cr(VI) to Cr(III), and chromate efflux. some of the se systems have been proposed as potential biotechnological tools for the b ioremediation of Cr pollution. In this review we summarize the interactions of bacteria, algae, fungi and plants with Cr and its compounds. (C) 2001 F ederation of European Microbiological Societies. Published by Elsevier Scie nce B.V. All rights reserved.