African Journal of
Microbiology Research

  • Abbreviation: Afr. J. Microbiol. Res.
  • Language: English
  • ISSN: 1996-0808
  • DOI: 10.5897/AJMR
  • Start Year: 2007
  • Published Articles: 5233

Full Length Research Paper

Statistical optimization of medium components for chromate reduction by halophilic Streptomyces sp. MS-2

Mona E. M. Mabrouk
Botany Department, Faculty of Science, Damanhour, Alexandria University, Egypt.
Email: [email protected]

  •  Accepted: 18 March 2008
  •  Published: 31 May 2008


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 37oC, 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.