Mosquitoes are one of the most dangerous insects in the world for humanity. Over one million people worldwide die from mosquito-borne diseases every year. Mosquito vectored diseases include protozoan diseases, i.e., malaria, filarial diseases such as dog heartworm, and viral diseases such as dengue, encephalitis, and yellow fever. In addition, mosquitoes transmit several diseases and parasites that dogs and horses are very susceptible too. These include dog heartworm, West Nile virus WNV , and eastern equine encephalitis EEE . Since its discovery, chemical insecticides have represented the most widely method used to control mosquito-borne vectors. However, the effects of chemical insecticides on mosquito vector populations are usually transitory because vectors can rapidly develop resistance against them. Each insecticide triggers the selection of one or more mechanisms of resistance. These mechanisms include changes in the target site of action and metabolic detoxification among others.

An intracellular nitrilase (Nit1) with cyanide-degrading activity was isolated from Trichoderma harzianum VSL291, cultivated on benzonitrile as the sole carbon source. Nit1 was purified to homogeneity by ion exchange and gel filtration chromatography with a recovery of 7.15% and a fold of 22.5. The molecular weight was estimated to be 47.7 kDa and the purified enzyme was sequenced with a system of liquid chromatography and mass spectrometry (LC-MS). The enzyme consists of 436 amino acids with a predicted molecular weight of 47.088 kDa. The sequence revealed conserved domains for a nitrilase super family such as putative active and binding sites and a Glu-Lys-Cys catalytic triad. Nit1 exhibited maximum activity (19.6 U mg -1 ) at 40 °C and a pH of 7.5. Nit1 had a strong inhibition in the presence of Al 3 +, Cu 2+ , Zn 2+ , and Ag + ions and was able to degrade KCN completely at 0.02 mmol/L, 0.05 mmol/L, and 0.1 mmol/L in 15 min, 40 min, and 45 min, respectively. The effect on KCN (0.02 mmol/L) degradation was tested in the presence of Cu2+ and Ag+ ions (0.025 mmol/L to 1.0 mmol/L) and the enzymatic activity was not affected significantly at 0.025 mmol/L, 0.075 mmol/L, and 0.125 mmol/L concentrations. However, when both ions were combined, the activity of the enzyme decreased significantly.