Comparative assessment of growth and biodegradation potential of soil isolate in the presence of pesticides

Abstract

In Pakistan, to increase agricultural production, higher amounts of fertilizers and pesticides are being used. The residues of the applied pesticides stay in the environment and therefore causing contamination of air, water and land. Moreover, agricultural industries are also contributing relatively high quantities of toxic pesticides into the environment. Since most of them have no treatment facilities. These pesticides may be toxic, mutagenic or carcinogenic. They may be bioaccumulated or biomagnified by the biota. Therefore its removal from environmental systems needs special attention. In this study, bacterial isolate, Pseudomonas, designated as IES-Ps-1, was used to assess its potential for pesticide removal from industrial wastewater using the biosimulator (activated sludge process). During experimental studies conducted in the flask as well as in biosimulator, it was observed that IES-Ps-1 grows normally at low concentrations of added insecticides when compared with the control test (without pesticide). However, at high concentrations the microbial count decreased but no death occurred and the culture remained in lag phase. In many cases, the growth of organisms in the presence of the particular substrate serves as an indication about its metabolic potential. However, to confirm these results, chemical oxygen demand (COD) and HPLC analysis were performed. Under aerobic culture conditions using mechanical aerators in biosimulator, almost complete removal of Cypermethrin at 20mg/L dose occurred during 48h. The study findings indicate that IES-Ps-1 strain, can be used for the treatment of the pesticide contaminated environment. Such study may be valuable to scientist and engineers, who are trying to develop methods for the treatment of toxic organic waste using the biological treatment process.