Isolation and identification of actinomycetes degrading the fungicid Allial from the activated sludge of the wastewater treatment plant Ibn Ziad (Constantine city)

The old methods of agriculture were based on the use of intensive manual labor. The twentieth century saw the birth of a revolution in agricultural practices, which relied mainly on plant protection techniques. These new perspectives have paved the way for an agriculture dominated by pesticides. The use of these molecules has improved yields and crop diversity to meet the nutritional needs of the growing world population. However, in recent years, other health and environmental problems have arisen due to uncontrolled overuse. Allial (fosetyl aluminum) is a systemic fungicide of the phosphonate class. It is not very persistent in soils and water and is recalcitrant to hydrolysis at environmental pH. This fungicide is also very soluble in water and can therefore reach surface waters by leaching from agricultural soils. Photolysis of this xenobiotic is not possible. In order to remove this fungicide from wastewater, biological treatment methods are necessary. Activated sludge microorganisms can play an important role in its biodegradation. In this study, were isolated actinomycetes from activated sludge of the wastewater treatment plant of Ibn Ziad. These bacteria, known by their extraordinary metabolic diversities, were tested for their aptitudes to degrade this toxic pesticide. Minimum salt medium supplemented with different concentrations up to 200 mg/L of fosetyl aluminum as the only carbon source. The cultures were incubated during 5 days at a temperature of 30° C. According to the results obtained, five isolates of actinobacteria showed a significant potential for the biodegradation of this fungicide. The identification of these isolates by analysis of the 16S rDNA gene allowed to assign them to the Streptomyces genus.