Genotoxicity of 2,4,5‐trichlorophenoxyacetic acid biodegradation products in the Salmonella reversion and lambda prophage‐induction bioassays

Abstract

Pseudomonas cepacia strain AC1100 has been isolated and reported to utilize 2,4,5‐trichlorophenoxyacetic acid (2,4,5 T) as sole carbon and energy source Metabolites from the 2,4,5‐T degradation pathway were tested for their mutagenicity in the Salmonella reversion bioassay and genotoxicity in the prophage‐induction bioassay The parental compound (2,4,5‐T) and three reported metabolites (2,4,5 trichlorophenol, 2,5‐dichlorohydroquinone, and 2‐chlorosuccinate) were negative with and without metabolic activation in Salmonella typhimurium strains TA98, TA100, TA102, and TA104 Conversely, 2,4,5‐T and 2,4,5 trichlorophenol were positive in the prophage‐induction bioassay with added S9 2,4,5‐Trichlorophenol was approximately 100 fold more genotoxic than 2,4,5‐T 2,5‐Dichlorohydroquinone was a weak direct‐acting genotoxicant in this assay In order to determine if strain AC1100 eliminated genotoxicity, 2,4,5 T medium was inoculated and the genotoxicity and the amount of 2,4,5‐T remaining were examined over the growth period As cell numbers increased, the percentage of 2,4,5‐T remaining in the medium decreased This decrease coincided with a decrease in genotoxicity in the prophage‐induction bioassay No mutagenic response was observed in the Salmonella reversion assay