Degradation of meta-trifluoromethylbenzoate by sequential microbial and photochemical treatments.

m- and p-trifluoromethyl (TFM)-benzoates are incompletely 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.