Fungal Metabolism of Toluene: Monitoring of Fluorinated Analogs by super(19)F Nuclear Magnetic Resonance Spectroscopy

Results are presented from a study in which fluorinated toluene isomers were used as substrate analogs and super(19)F nuclear magnetic resonance spectroscopy was used to characterize the pattern of metabolite accumulation as the first steps in the catabolism of toluene in six previously isolated fungi capable of growth on toluene as a sole carbon and energy source. The results show that fungi that degrade toluene by cometabolism and those that use it as the sole carbon source both degraded the fluorinated analogs, but at very different rates. All six fungi converted 2-, 3-, and 4-fluorotoluene to intermediates that matched the toluene metabolic pathway proposed for Cladosporium sphaerospermum. The data suggest that toluene was assimilated via an initial oxidation of the methyl group, with toluene first hydroxylated to benzyl alcohol and then dehydrogenated to benzoate via a putative aldehyde intermediate.