Biodegradation of Difenoconazole Using Fungal-Bacterial Consortia

Abstract

Abstract Pesticides are used all over the world in agricultural operations to reduce the damage of pests and to improve the productivity of agricultural crops. The excessive use of these chemical compounds has led to the deterioration of soil and increase the level of pollution of water and air resources. Moreover, the continuous use and non-target toxicity of pesticides has become a major concern to the agricultural ecosystem that directly hinders the productivity of agricultural products. Therefore, this study aimed to isolate and identify fungal and bacterial species with the ability to biodegrade fungicide via conducting preliminary tests to find out which of them have the ability to grow in a treated medium with a fungicide Difenoconazole, which belongs to the group of the pesticides Triazoles. The fungi and bacteria that succeeded in growing were as follow Aspergillus flavus, Aspergillus ochraceus, Bacillus cereus S1 and Bacillus cereus S2 were identified by extracting their genomic DNA and applying the primers ITS and 16s rRNA for both examined fungi and bacteria, respectively. The fungi were laboratory adapted to multiple concentrations reaching the highest concentration of 550 mgL-1, while bacteria reached 1200 mgL-1 laboratory to break down the pesticide. The results of the combinations tested as the B. cereus S1 and B. cereus S2 were the fastest growing in the liquid medium PDB at the concentration of 325 mgL-1. While the combination A. flavus and B. cereus S1 had the highest biodegrading ability at the same concentration, which led to the disappearance of the pesticide Difenoconazole turbidity in the liquid medium as a result of its consumption by fungal and bacterial isolates. As for the treatment of the pesticide in the solid PDA medium to know its effect on the growth of fungi and the formation of spores, the results revealed that fungal isolates increase their vegetative growth when the concentration increases, the production of fungal spores decreases, and indicates the ability of the fungi to use the pesticide as an energy source.