Biodegradation of chlorphyrifos byKlebsiella sp. isolated from an activated sludge sample of waste water treatment plant in damascus
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A chlorpyrifos (CPY)-degrading bacterial strain was isolated from an activated sludge sample collected from theDamascus Wastewater Treatment Plant, Syria. The isolation ofKlebsiella sp. was facilitated by the addition of CPY at a rate of 3.84 g/L of sludge weekly (selection pressure). Identification ofKlebsiella sp. was done using major staining and biochemical differentiation tests (Gram stain, cytochrome oxidase and some relevant saccharide fermentation tests using biochemical assays).Klebsiella sp. was maintained by culturing in a poor medium consisting of mineral salts and CPY as the sole carbon source. When 3 activated sludge samples were incubated in the presence of CPY (13.9 g/L sludge), 46 % of added CPY were degraded within 4 d. By comparison, within 4 d the isolatedKlebsiella sp. was found to break down 92 % of CPY when co-incubated in a poor mineral medium in which CPY was the sole carbon source (13.9 g/L poor medium). IsolatedKlebsiella sp. was able to tolerate up to 17.3 g of CPY in the poor medium.
KeywordsSole Carbon Source Chlorpyrifos American Public Health Association Methyl Parathion Waste Water Treatment Plant
Damascus Wastewater Treatment Plant
mineral salt medium
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