International Journal of Environmental Sciences

Present study reports the isolation of malathion insecticide degrading bacteria from soil contaminated with malathion insecticide and their growth rate assessed in Minimal salt broth containing 50ppm of pesticides at different temperature levels viz., 25°C, 35°C, 45°C, 55°C and different pH levels viz., pH 4, pH 5, pH 6, pH 7, pH 8 and different carbon sources viz., Dextrose, Fructose, Lactose, and different nitrogen sources viz., Peptone, Yeast extract, Beef extract respectively. The isolation of pesticide degrading bacteria was carried out using Mineral Salts Medium (MSM) and the isolated bacterial isolates were identified as Bacillus amyloliquefaciens and Pseudomonas species based on staining techniques and plating on selective media. Between the two bacterial isolates, the bacteria Bacillus amyloliquefaciens, designated as MS 1 utilized the pesticides effectively and showed maximum growth. The maximum growth rate of bacteria was recorded at 35°C followed by 25°C, 45°C and 55°C and pH 7 followed by pH 6, pH 8, pH 5 and pH 4. Moreover, the growth of bacteria was maximum in the presence of Dextrose followed by Fructose and Lactose and in Peptone followed by Yeast extract and Beef extract.