Extensive Degradation of Silvex by Synergistic Action of Aquatic Microorganisms

The herbicide 2-(2,4,5-trichlorophenoxy)propionic acid (silvex) was extensively degraded by a mixed culture of a Pseudomonas species and an Achromobacter species isolated from farm pond water. Neither of the two organisms separately was able to metabolize the herbicide. In the degradation of silvex by the mixed culture, chlorine was liberated from the herbicide, the aromatic ring was cleaved, and CO₂ was evolved. Except for a minor amount of 2,4,5-trichlorophenol, no silvex metabolites as detected by TLC were found. The mixed culture also readily decomposed 2,4,5-trichlorophenol and 3,5-dichlorocatechol.