Abstract

Extensive use of hexavalent chromium Cr(VI) in various industrial applications has caused substantial environmental contamination. A marine bacterium,Streptomyces sp. MS-2 showed a high Cr(VI) reduction performance.Streptomyces sp. MS-2 completely reduced 75 mg/l Cr(VI) within 72 h of growth. The effectiveness of the bacterium for reducing Cr(VI) under different conditions was evaluated. Optimum pH and temperature were 7.0 and 37^oC, respectively. Statistical screening of medium components for Cr reduction by Streptomyces sp. MS-2 was carried out by Plackett–Burman design. Peptone, yeast extract, inoculum size, and volume of the medium were shown as significant components influencing Cr(VI) reduction. By applying a verification experiment, Streptomycessp. MS-2 completely reduced 75 mg of Cr(VI) to Cr(III) within 12 h. This optimization strategy led to a 6-fold increase in the reduction rate. This holds great promise for detoxification of Cr(VI) under a wide range of environmental conditions.

Key words: Streptomyces MS-2, hexavalent chromium, Plackett–Burman design.