Chromium, the seventh most abundant element on earth, is a group VI-B transition metal. It is found in nature in bound form constituting approximately 0.1 to 0.3 mg.g-1 of the earth's crust. . The element's name is derived from the Greek word "chroma" meaning color, as many of its compounds are intensely colored. Cr can exist in several oxidation states, among which the trivalent Cr(III) and hexavalent Cr(VI) species are the most stable and abundant forms (Zayed & Terry et al., 2003). The most stable form of chromium is its trivalent oxidation state which is mainly found geologically in the form of chromite (FeCr2O4) (Cervantes et al., 2001). Cr(III) is of natural origin, while Cr(VI) is of anthropogenic origin. This is the result of the dissolution of chromite and subsequent oxidation of Cr(III) to aqueous Cr(VI) in the presence of the common manganese mineral birnessite (Oze et al., 2007). Cr(VI) generally associates with oxygen to form the oxyanions chromate (CrO42-) and dichromate (Cr2O7 2-). Cr(VI) compounds are highly soluble and therefore mobile in aquatic systems, while Cr(III) derivatives, in the form of hydroxides, oxides and sulfates, are insoluble in water and exist primarily linked to organic matter in soils and aquatic systems (Cervantes, C et al., 2001; Zayed and Terry, 2003). Chromium differs significantly in its physicochemical properties and biological reactivity with respect to its oxidation states. While Cr(VI) species and dichromates are extremely soluble in water and mobile in the environment, Cr(III) species are much less soluble and relatively immobile (Viamajala et al., 2004). Chromium is an essential micronutrient necessary for the growth of many species. microorganisms for maintenance...... middle of paper ...... heavy metals (Ha et al., 2010). The majority of bacteria used in biosorption systems produce EPS which plays a key role as bio-sorbents for metal remediation and recovery (Sheng GP et al., 2010). There are several negatively charged functional groups such as hydroxyl, carboxyl, phenolic and sulfhydryl groups present in EPS which help in the adsorption of chromium (Sethuraman P et al., 2010). . Exopolysaccharides (EPS) which help in the fixation, tolerance and reduction of hexavalent chromium (Ozturk et al., 2009). Studies relating to the reduction of hexavalent chromium to trivalent form by native microbial species isolated from different sources have been reported in the past (Sethuraman P. et al., 2010; Wei-hua XU et al., 2009; K. Sundar et al., 2011). The central role of EPS as well as the cell in chromium adsorption and reduction has been noted (K. Sundar et al.., 2011).