Comparative Analysis of Chemical, Fungal and Enzymatic Degradation of MCP

Abstract

In general three different methods are used for the cleanup of pesticides. These include chemical, microbial and enzymatic methods. Therefore, the present study is an endeavor to compare the efficiency of all the three methods for the study of degradation of monocrotophos (MCP) (150 µgml -1 ). Chemical method involved the use of 0.1N NaOH, whereas for the biological as well as enzymatic method, molecularly characterized fungal strain Aspergillus niger JQ660373 was used. %age of MCP degradation was assessed in the form of residual MCP concentration and hence degradation kinetics was premeditated. The results were confirmed by using analytical tools, High Performance Thin Layer Chromatography (HPTLC) and Fourier Transfom Infrared (FTIR). Results of the study demonstrated that degradation of MCP followed first order kinetics with the calculated half-life of 0.79 days in enzymatic method as compared to 3.16 and 4.21 days for fungal and chemical method. HPTLC chromatograms clearly indicate significant decrease in the standard MCP peak (rf 0.19-0.21) with increasing incubation duration. Molecular insight of MCP degradation as studied, suggests hydrolytic cleavage of MCP resulting in the formation of inorganic phosphates (-PO 4 ) and amines. The overall efficiency of degradation was found to be Enzymatic > Fungal > Chemical. The term "pesticide" embraces an enormous diversity of products that are used in a number of different activities and are intended for preventing, destroying, repelling or mitigating pests. Among newly developed pesticides, organophosphorus pesticides (OPPs) are most commonly used as they degrade faster in the environment. MCP (Dimethyl (E)-1-methyl-2 methyl carbamoyl vinyl phosphate) is an organophosphate with broad-spectrum contact and systemic activity against spur throated locust, sorghum midge, western flower thrips, aphids, the green vegetable bug, mites, the stem borer, potato tuber moth which are common pests of sorghum, sunflowers, tomatoes, cotton, potato, soybean and tobacco [1,2].Despite increasing crop productivity MCP is highly toxic to human beings. Mechanism of toxicity of MCP involves irreversible acetyl cholinesterase inhibition [3].Owing to its highly toxic nature, degradation of MCP from the environment is very essential. Degradation of MCP occurs by biotic as well as abiotic factors of the natural environment. These factors influence the degradation of MCP and act in tandem and complement one another in the microenvironment [4].Traditional cleanup methods of pesticides include the use of chemicals. These chemicals pose hazards on the soil fertility and soil microbial flaura and fauna. Therefore, these methods were discarded and biological methods emerged as a new tool for the degradation of pesticides.