FORMATION OF TOLUENE BY MICROORGANISMS FROM ANOXIC FRESH-WATER SEDIMENTS

In artificial anoxic lakewater that had been inoculated with anoxic lake sediment, toluene was liberated by microorganisms and accumulated in the water. Phenylalanine, phenyllactate and phenylpyruvate proved to be effective precursors. Media supplemented with phenylacetate developed toluene even in a shorter period of time than the other three compounds. 2-Phenylethanol, phenylacetaldehyde, and phenylacetic acid ethyl ester only weakly supported the formation of toluene. The effectiveness of benzaldehyde was very low, and cinnamate did not at all support the formation of toluene. The transformation of phenylalanine to toluene was complete and resulted in the formation of stoichiometric amounts. Labelling experiments with deuterated phenylalanine showed no loss of label in the toluene molecule and no dilution by unlabelled toluene. The experiments support the view that phenylalanine that has been liberated from proteinaceous matter by hydrolysis is degraded in anoxic hypolimnia of lakes and anoxic sediments of rivers only to the stage of toluene. This reaction is responsible for the accumulation of toluene in these environments.