A study on biodegradation of propoxur by bacteria isolated from municipal solid waste

Abstract

Five different types of bacteria were isolated from Municipal Solid Waste and identified as Neisseria subflava, Staphylococcus aureus, Corynebacterium kutscheri, Bacillus pasteurii and Aeromonas species. Of these five different types, Neisseria subflava and Staphylococcus aureus were capable of growing on propoxur containing media. These two bacteria were grown on synthetic broth containing 100 and 200 ppm of propoxur respectively for 12 days. Residual phenol produced as a metabolite was estimated every 24 hours by colorimetry using 4 -aminoantipyrine method. Degradation pattern showed that, Neisseria subflava and Staphylococcus aureus degraded propoxur into residual phenol and basic compounds. Neisseria subflava showed constant increase in degradation of propoxur over the time after 144hrs of exposure to propoxur at 100 and 200 ppm. Nevertheless, degradation of 200 ppm propoxur was comparatively less than that of 100 ppm propoxur by Neisseria subflava. Staphylococcus aureus showed zigzag pattern of degradation indicating that for every 24 or 48 hrs of degradation of propoxur, there was decrease in growth rate indicating that the metabolite of propoxur was inhibiting the growth and then there was recovery once again leading to increased growth rate for another 24 hrs.