Microbial Detoxification of Dimethoate and Methomyl Residues in Aqueous Media

Abstract

The extensive and random application of major organic pollutants, mainly pesticides, threatens ecosystems and human health. The present study was conducted to isolate and identify microorganisms from some water resources contaminated with pesticides. We investigated the ability of the identified microbes to grow in water spiked with dimethoate and methomyl. We also evaluated the potential effect of the identified microbial isolates on dimethoate and methomyl biodegradation in water. In addition, the total detoxification of dimethoate and methomyl residues in water after treatment with the most effective microbial isolates was confirmed using toxicity tests and analyzing biochemical parameters and histopathological changes in the kidney and liver of treated rats. The microbial isolates were identified as Xanthomonas campestris pv. Translucens and Aspergillus fumigates. Results showed that X. campestris pv. Translucens and A. fumigatus grow in media supplemented with dimethoate and methomyl faster than in other media without both pesticides. About 97.8% and 91.2% of dimethoate and 95% and 87.8% of methomyl (initial concentration of both 5 mg L−1) were biodegraded within 32 days of incubation with X. campestris pv. Translucens and A. fumigatus, respectively. There was no remaining toxicity in rats treated with dimethoate- and methomyl-contaminated water with respect to biochemical parameters and histopathological changes. Collectively, the identified bacterial isolate showed high potential for the complete degradation of dimethoate and methomyl residues in water.

Photocatalytic Detoxification of Some Insecticides in Aqueous Media Using TiO2 Nanocatalyst

“…The application of heterogeneous photocatalytic water purification processes has gained considerable attention the last few years resulting from its effectiveness in degrading and mineralizing the recalcitrant organic compounds and also because of the possibility of using solar UV and the visible-light spectrum [5][6][7]16,17]. Recently, water treatments with a nanocatalyst have been considered as a potential treatment and are becoming increasingly available worldwide because of the effective production of nanomaterials with modest resources and less waste (i.e., reducing pollution).…”

“…It should be stressed that pesticide contamination of surface and groundwater from agricultural use has been a concern for a long time [4][5][6][7][8][9]. In the last few decades, contamination by organochlorine pesticides (OCPs), organophosphorus, and carbamates has attracted considerable attention due to their resulting toxicity and persistence in the environment.…”

“…Several conventional methods have been adopted for treatment of surface and groundwater sources contaminated with pesticides; however, the advanced oxidation method has been considered among the most effective technologies [16][17][18][19]. Advanced oxidation processes (AOPs), constituted by the combination of several oxidants, are characterized by the generation of very reactive and oxidizing free radicals in aqueous solutions such as hydroxyl radicals, which possess great destruction power [5][6][7][16][17][18]. To the best of our knowledge, conventional photocatalysts such as TiO 2 and ZnO can be used in low initial concentrations not only to remove pesticides [5][6][7]9,17,20,21], but also other organic pollutants [22].…”

“…Advanced oxidation processes (AOPs), constituted by the combination of several oxidants, are characterized by the generation of very reactive and oxidizing free radicals in aqueous solutions such as hydroxyl radicals, which possess great destruction power [5][6][7][16][17][18]. To the best of our knowledge, conventional photocatalysts such as TiO 2 and ZnO can be used in low initial concentrations not only to remove pesticides [5][6][7]9,17,20,21], but also other organic pollutants [22]. Heterogeneous photocatalysis containing semiconducting photocatalysts used in AOPs has recently emerged as an advanced oxidation process in an environmental decontamination method suitable for the treatment of water, aqueous wastes, and wastewater [17,[23][24][25].…”

“…However, after remediation of pesticide residues in water, a toxicity assessment is still required to confirm the complete detoxification of any possible potential hazard from both original pollutants and their metabolites [6,7,16]. This method remains inaccurate because sometimes the degradation products of pesticides are more toxic than the pesticides themselves.…”