Investigating the degrading properties of three different strains of fungi on commonly used pesticides in Guyana

Abstract

Abstract. Fareed R, Ansari A, Seecharran D, Munroe L. 2017. Investigating the degrading properties of three different strains of fungi on commonly used pesticides in Guyana. Biofarmasi J Nat Prod Biochem 15: 5-14. Bioremediation is the use of microbes to remove various contaminants from the environment. The present research work was carried out from 2014 to 15. Aspergillus niger, Aspergillus flavus, and Penicillium spp. were employed for the biodegradation of pesticides commonly used in Guyana. Initially, the fungi were screened for ligninolytic potential by observing the decolorization/degradation of a synthetic dye (Remazol Brilliant blue) in PDA agar. The degradation of dyes was noted by the change in the original color of the dye and the visual disappearance of color from the fungus-treated Petri plates. In addition, the accumulation of the dye by the fungal mycelium was also noticed. The fungi were then tested for their tolerance to the pesticides Diuron, Malathion, and Diazinon, respectively. Using PDA agar with amoxicillin on solid media to prevent bacterial growth. The pesticides were introduced to the fungi by way of disc diffusion. Discs of a known diameter were infused with the respective pesticides at different concentrations and placed at strategic points around the inoculated fungal mycelium. The extent of inhibition was measured by comparing the growth diameter in the sample versus the growth in the control. The pesticide diazinon was found to have inhibited the fungi more when compared to Malathion and Diuron. Finally, the fungi were used to degrade the pesticides in a liquid culture-Peptone Broth. The pesticide Diuron was selected because the fungi thrived best in all pesticide concentrations. The pesticide Diuron concentration was placed in flasks containing the peptone broth with mycelial discs of the respective fungal strain. The final concentration of the pesticide was determined by using High-Performance Liquid Chromatography (HPLC). The concentration of the pesticide in each strain of fungi was decreased. Aspergillus niger was found to have the highest rate of pesticide degradation, followed by Aspergillus flavus and Penicillium.