Detoxification and Bioremediation Potential of a Pseudomonas fluorescens Isolate against the Major Indian Water Pollutants

A Pseudomonas fluorescens strain was isolated from the soil of industrial estate of Aligarh, India. This strain was resistant to some of the major Indian water pollutants, namely Cd²⁺, Cr⁶⁺, Cu²⁺, Ni²⁺, Pb²⁺, BHC, 2,4-D, mancozeb and phenols up to the levels occurring in the highly polluted regions. Moreover, the test strain seems to have a great potential for the detoxification of these pollutants. The decrease in toxicity as determined by the Allium cepa test was recorded as 62.5% for the model water containing the mixture of test heavy metals, 71.9% for the pesticides, 73.2% for phenols, and 58.5% for combination of all these toxicants. These values were obtained after 24 hours, exposure to the immobilized cells of the test isolate in the calcium alginate matrix at the concentrations of these polutants supposedly present in the highly polluted water systems in India. The efficiency of bioremediation for certain heavy metals at the same concentrations by means of immobilized cells of the test Pseudomonas fluorescens isolate was estimated to be 75.9% for cadmium, 74.2% for hexavalent chromium and 61.0% for lead during the 24 hours' treatment. In view of the preliminary work, the test isolate seems to be a good candidate for the bioremediation of water pollutants.

Keywords:

• Bioremediation
• Detoxification
• Pseudomonas fluorescens
• Water pollutants

ACKNOWLEDGMENTS

The authors are thankful to the university authorities for providing the essential facilities for carrying out this research.

Notes

*Each experiment was performed twice and the plates for each dose were run in triplicate. Values are mean ± SD.

*Heavy metals: a mixture of Cd²⁺ + Cr⁶⁺ + Pb²⁺

**1× heavy metals : Cd²⁺ (124 ppm) + Cr⁶⁺ (10 ppm) + Pb²⁺ (198.18 ppm).

***Inhibition with respect to −ve control i.e. without toxicants.

****Efficiency of detoxification = percent inhibition in untreated—percent inhibition in treated samples at the toxicants concentrations.

*Pesticides: a mixture of BHC + 2,4-D + mancozeb.

**1× Pesticides : BHC (500 ppb) + 2,4-D (78 ppb) + mancozeb (312 ppb).

***Inhibition with respect to control i.e., without toxicants.

****Efficiency of detoxification = percent inhibition in untreated—percent inhibition in treated samples at the same toxicants concentrations.

*Phenols: a mixture of catechol + cresol + phenol + resorcinol.

**1× phenols: cathechol (110 ppm) + cresol (108 ppm) + phenol (94 ppm) + resorcinol (110).

***Inhibition with respect to control i.e., without toxicants.

****Efficiency of detoxification = percent inhibition in untreated—percent inhibition in treated samples at the same toxicants concentrations.

*Toxicants: a mixture of heavy metals + pesticides + phenols.

**Inhibition with respect to control i.e., without toxicants.

**Percent detoxification = percent inhibition in untreated—percent inhibition in treated samples at the toxicants concentrations.

*AAS—Atomic absorption spectrophotometer.

**Percent bioremediation × 100.