Chlorpyrifos biodegradation by a Locally Isolated Bacterium Pseudomonas sp. B5-2

Chlorpyrifos has been considered as one of the most frequently used organophosphorus insecticides in agriculture worldwide. There has been considerable public concern regarding its neurotoxicity and its genotoxicity on mammals, aquatic organisms, and other non-target species. In this study 23 bacterial isolated strains from different origins were tested for their ability to resist and subsequently degrade chlorpyrifos (CP). Seven of these strains showed a resistance to up to 1000mg/L CP on solid minimal mineral salt medium (MMSM) and the strain Pseudomonas sp. B5-2 was selected for further analysis after a selection on liquid MMSM. The effect of different concentrations of CP on the growth of the selected strain was tested, and 200 mg/L was the highest concentration that supports its growth. The ability of the selected strain to eliminate CP was investigated in the presence and in the absence of glucose as an external carbon source. The results showed that the strain utilized chlorpyrifos (200 mg/L) as the sole source of carbon better than in presence of an external carbon source (glucose) with an elimination rate of 67.06% and 14.61%, respectively. These results highlight the potential of this bacterium to be used in the cleanup of contaminated pesticide waste in the environment.