Chromate resistance, transport and bioreduction by Exiguobacterium sp. ZM-2 isolated from agricultural soil irrigated with tannery effluent
✍ Scribed by Mohammad Zubair Alam; Abdul Malik
- Book ID
- 102391822
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 145 KB
- Volume
- 48
- Category
- Article
- ISSN
- 0233-111X
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✦ Synopsis
Abstract
Bacterial strain Exiguobacterium sp. ZM‐2 isolated from agricultural soil irrigated with tannery effluents, was examined for its resistance to hexavalent chromium. Exiguobacterium sp. ZM‐2 could resist 12.37 mM of potassium chromate. The isolate was also found resistant to other heavy metal ions. Exiguobacterium sp. ZM‐2 was able to reduce 500 μM hexavalent chromium completely within 56 h under in vitro conditions. Chromate reduction was severely affected in presence of metabolic inhibitors, sodium cyanide and sodium azide. No chromate reduction was observed in presence of 1 mM sodium cyanide while only 17% of 250 μM chromate was reduced when medium contained 1 mM sodium azide. A 10 mM sodium sulphate inhibited hexavalent chromium reduction up to 35%. On the other hand, use of 1 mM 2, 4‐dinitrophenol, an uncoupling agent, stimulated the chromate reduction, indicating that the respiratory‐chain‐linked electron transport to Cr (VI) was limited by the rate of dissipation of the proton motive force. Cell free extract of Exiguobacterium sp. ZM‐2 readily reduce Cr (VI) to Cr (III). The kinetics of chromate reductase fit well in the linearized Lineweaver‐Burk plot and showed a K~m~ of 106.1 μM Cr (VI) and V~max~ of 1.24 μmol/min per mg of protein. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)