Cr(VI) reduction by Bacillus coagulans isolated from contaminated soils
- Indian Inst. of Tech., Kharagpur (India)
- Univ. of West Indies, St. Augustine (Trinidad and Tobago). Dept. of Civil Engineering
Investigation on Cr(VI) reduction was conducted using bacteria isolated from soil samples receiving electroplating wastewater. Chromium reduction capacity of these isolates was compared with that of Pseudomonas aeruginosa, a pure culture procured from the Institute of Microbial Technology, as well as Bacillus circulans, a laboratory isolate from garden soil. Bacillus coagulans, isolated and identified from chromium polluted soil, gave maximum reduction potential among all organisms studied. Malate was found to yield maximum biotransformation out of four electron donors employed. B. coagulans was able to reduce Cr(VI) even at 10 mM initial Cr(VI) concentration. With an increase in initial cell density, Cr(VI) reduction capacity was also increased; however, maximum specific biotransformation occurred at low cell densities. The optimum pH for Cr(VI) reduction was 7. Sulphates and nitrates did not compete with Cr(VI) for accepting the electrons. The presence of respiratory inhibitors like DNP and NaN{sub 3} marginally reduced the Cr(VI) reduction capacity. Cell free extracts were able to reduce Cr(VI) even in the absence of external electron donors; however, marginal increase was found in the presence of malate, nicotinamide adenine dinucleotide, and reduced nicotinamide adenine dinucleotide. The contribution of cell membrane in Cr(VI) reduction was negligible. Hence, the soluble enzymes appear to be responsible for Cr(VI) reduction by B. coagulans.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 302240
- Journal Information:
- Journal of Environmental Engineering, Vol. 124, Issue 12; Other Information: PBD: Dec 1998
- Country of Publication:
- United States
- Language:
- English
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