Microbial Degradation of Organophosphate Pesticides
Organophosphate (OP) pesticides are widely used for controlling pests and insects for better crop production in many countries. They have become an inevitable part of the modern environment as they are widely used in agriculture, household, and public health sectors and, hence, are extensively distributed throughout most ecosystems. But indiscriminate use and lack of proper technical knowhow have resulted in contamination and pollution of large varieties of ecological niches. Aside from causing environmental contamination, they affect human health especially by over-stimulating of the neurotransmission system. OP pesticides, as with other non-persistent pesticides, degrade quickly in the environment as well as are metabolized quite rapidly in humans. Depending on their fate, these OP pesticides may become bioavailable for microbial degradation. Environmental microbes, such as Aspergillus, Pseudomonas, Chlorella, and Arthrobacter, are capable of coupling a variety of biochemical mechanisms for the degradation of organophosphate pesticides, including adsorption, hydrolysis of P–O alkyl and aryl bonds, photodegradation, and enzymatic mineralization. Enzymes, such as esterase, somanase, diisopropylfluorophosphatase, phosphotriesterase, parathion hydrolase, and paraoxonase, have been isolated from microbes to study and understand the catabolic pathways involved in the biotransformation of these xenobiotic compounds. This review highlights various aspects of biodegradation of organophosphate pesticides along with biological and molecular characterization of some organophosphate pesticide-degrading bacteria.