Degradation of Monocrotophos in Sandy Loam Soil by Aspergillus sp

摘要

The present study premeditated to explore and compare the potential of Aspergillus sp. to degrade monocrotophos in soil. Two different strains of Aspergillus sp. viz Aspergillus niger JQ660373 and Aspergillus flavus, were tested under anaerobic conditions for their monocrotophos (150 μg Kg-1) degrading ability in sandy loam soil for a period of 30 days. The water-holding capacity was maintained at 60% and samples were incubated at 25 ± 4 °C. After regular time interval of 5 days, the samples were collected and estimated for residual monocrotophos concentration. Residual monocrotophos was extracted with ethyl acetate and estimated by spectrophotometric method at 254nm. The degradation of monocrotophos in soil was observed to be rapid and followed first order kinetics. A 99% of applied pesticide was degraded within 30 days of incubation. It was found that Aspergillus niger was more efficient for the degradation of monocrotophos than Aspergillus flavus. The half life of monocrotophos for Aspergillus niger and Aspergillus flavus was found to be 7.35 and 9.23 days, respectively. Degradation process was assessed by HPTLC and FTIR analysis. These revealed reduction in the peak of standard monocrotophos as a measure of hydrolytic cleavage of vinyl bond with the formation of inorganic phosphates and release of carbon dioxide and ammonia. It could be concluded from the study that these two fungal strains had the ability to degrade monocrotophos in soil.