Microbial degradation of organophosphorus pesticides using whole cells and enzyme extracts

The use of microbial phosphotriesterases in the degradation of organophosphorus compounds employed as pesticides, plasticizers and petroleum additives is a sustainable alternative for bioremediation of water and soils, decontamination of particular foods and as poisoning antidote. Whole cells of six wild type microorganisms-Streptomyces phaeochromogenes, Streptomyces setonii, Nocardia corynebacterioides, Nocardia asteroides and two Arthrobacter oxydans-selected in our lab as phosphotriesterase sources, were further tested as biocatalysts in the hydrolysis of paraoxon, methyl paraoxon, methyl parathion, coroxon, coumaphos, dichlorvos and chlorpyrifos, highlighting 98% conversion of chlorpyrifos into its hydrolysis products using whole cells of S. phaeochromogenes at pH 8 and 40 °C. Immobilized whole cells and enzyme extracts were also assessed, observing as a general trend, that there is no significant variation in hydrolytic activity between them. These results suggest that according to the circumstances, immobilized whole cells (avoiding cellular disruption and centrifugation) or enzyme extracts (which can be handled more easily) could be used.

Bacteria; Biodegradation; Bioremediation; Organophosphorus compounds; Pesticides; Phosphotriesterases.