The Removal of Confidor Pesticide by Different Species of Trichoderma Fungi from Contaminated Waters

Introduction: Pesticides are considered as the most important pollutants in surface water and groundwater. Neonicotinoids are new group of insecticides, derived from nicotine. Their physicochemical properties render them useful for a wide range of application techniques, including foliar, seed treatment, soil drench and stem applications. Confidor, the representative of the first generation of neonicotinoid insecticides, was patented in 1985 by Bayer and was placed on the market in 1991. The Canadian Pest Management Regulatory Agency considers confidor to have high potential for surface water contamination, leaching to groundwater and persistence in soils. Biodegradation is one of the most effective ways to destroy pesticides in the environment. The application of Bioremediation techniques is taken into consideration as an option to reduce or remove pollutants from the environment due to their low cost, high efficiency and environmentally friendly features. Bioremediation by using microorganisms has not any adverse effect after cleanup. The accumulator microorganism species, haven’t pathogenic properties and aren’t the cause of disease on the other organisms. The selection of a biomass for using in bioremediation is very important, it should be abundant in environment and adapted to environmental conditions. The aim of this study was to investigate the ability of various species of Trichoderma fungi to remove Confidor from contaminated water influenced by variables like pH, concentration of the confidor and time. Materials and Methods: In order to conduct this study three different fungal species belonging to the genus Trichoderma were used. The samples were transferred to PDA (Potato Dextrose Agar) sterile solid media for in vitro testing usage. The samples were kept in refrigerator at 4◦C temperature, after the fungal biomass reached to maximal growth; the colonies were transferred to new media and used in our experiments as resources. After complete fungal growth on the solid media, liquid media were prepared with the formula containing 250 g/l potato extract, 20 g/l dextrose and 0.25 g/l Tetracycline antibiotic (to prevent bacteria growth) in three pH (5,7,9) and three toxicant concentrations (1, 3 and 5 mg/l). Lactic acid and KOH (3%) were used to adjust pH in the prepared media. The degradation experiments were performed in a 50 ml falcon for 1 month. All experiments were maintained under similar conditions. The samples were shacken daily. After 1 mo