Degradation of meta-trifluoromethylbenzoate by sequential microbial and photochemical treatments

Abstract m - and p -trifluoromethyl (TFM)-benzoates are completely degraded by aerobic bacteria that catabolize alkylbenzoates; biodegradation ceases after ring-fission with the accumulation of a trifluoromethyl muconate semialdehyde (2-hydroxy-6-oxo-7,7,7-trifluorohepta-2,4-dienoate, TFHOD) which is resistant to biochemical attack. A bacterium (Strain V-1), isolated from sea-water, grew aerobically on benzoate or m -toluate. Cells grown on benzoate or m -toluate oxidized both compounds at similar relative rates. Catabolism involved benzoate 1,2-dioxygenase (decarboxylating) and meta -cleavage to yield muconate semialdehydes. Cells grown on benzoate metabolized m -TFM-benzoate to TFHOD. The ring-fission products from m -toluate and TFHOD were degraded by sunlight, and equimolar fluoride was released from TFHOD. Sequential biochemical and photochemical treatment allowed the destruction of m -TFM-benzoate beyond the biochemically recalcitrant intermediate TFHOD.