Bioremediation of Malathion from Environment by an IsolatedBacillussp. S14

Pesticide pollution has been increased owing to their growing use to increase agricultural productivity. Pesticide residues are causing serious ecological problems as they are harmful to nontarget organisms. Physical and chemical methods of removal of pesticide molecules often involve a lengthy and expensive treatment process. In this respect bioremediation of pesticide is more effective. A bacterial strain Bacillus species (S14) capable of removing Malathion was isolated and identified in our laboratory. Maximum Malathion removal (68%) using growing cells was observed under the following environmental conditions: 50 ml medium in a 250 ml Erlenmeyer flask, pH 7.5, temperature 28°C, shaker speed 120 rpm, initial Malathion concentration 50 mg/l, inoculum concentration 4% (20 h cell suspension). Maximum Malathion uptake (90.09%) by the isolated strain occurred at pH 6.5, temperature 25°C, using 0.32 g/l washed biomass (dry basis) in 6 h. Freundlich isotherm had a better fit with the data. Scanning electron micrographs exhibited adsorption of the pesticide on the cell surface of the Bacillus species (S14). Functional groups responsible for biosorpton were identified by infrared spectral analysis. Different functional groups, such as amine, amide present on cell surface are mainly responsible for adsorption process.