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Experimental study on Cr (V) reduction by Pseudomonas aeruginosa
Yun-Guo Liu1, Wei-Hua Xu, Guang-Ming Zeng
1Department of Environmental Science and Engineering, Hunan University, Changsha 410082, China.
Journal of Environmental Sciences (China)
|November 24, 2004
Summary
Pseudomonas aeruginosa effectively reduces toxic hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)). Optimal conditions include malate as a carbon source and a neutral pH, with increased cell inoculum enhancing the reduction rate.
Area of Science:
- Environmental microbiology
- Bioremediation
- Biotechnology
Background:
- Hexavalent chromium (Cr(VI)) is a toxic heavy metal pollutant.
- Bioremediation using microorganisms offers a sustainable approach for chromium detoxification.
- Pseudomonas aeruginosa is a bacterium with known metabolic capabilities.
Purpose of the Study:
- To investigate the efficiency of Pseudomonas aeruginosa in reducing Cr(VI) to Cr(III).
- To identify optimal conditions for Cr(VI) bioreduction.
- To elucidate the mechanism and end products of Cr(VI) reduction.
Main Methods:
- Microbial reduction experiments using Pseudomonas aeruginosa.
- Optimization of factors: carbon source, pH, initial Cr(VI) concentration, and cell inoculum.
- Analysis of reduction products and mechanism.
Main Results:
- Malate yielded the highest Cr(VI) biotransformation (60.86%), followed by succinate and glucose.
- Optimal pH for reduction was 7.0, achieving 61.71% efficiency.
- Reduction rate decreased with increasing Cr(VI) concentration, inhibited above 157 mg/L.
- Increased cell inoculum enhanced the reduction rate.
- Soluble enzymes were identified as the primary agents of reduction, with Cr(III) remaining soluble.
Conclusions:
- Pseudomonas aeruginosa is a potent agent for Cr(VI) bioremediation.
- Bioreduction is influenced by carbon source, pH, substrate concentration, and microbial biomass.
- The process involves soluble enzymes and results in soluble Cr(III).