TRANSFORMATION OF PHENOL INTO PHENYLALANINE BY A METHANOGENIC CONSORTIUM

The conversion by a methanogenic consortium of phenol into phenylalani ne, with benzoic and phenylpropionic acid as intermediates, was invest igated, When C-14-labelled phenol was fed to the consortium, the radio activity was mostly transferred into methane and CO2, but 4% of the ra dioactivity was found in the water fraction after extraction of the cu lture medium with an organic solvent. Utilization of labelled compound s and analysis by gas chromatography coupled with mass spectrometry re vealed that a fraction of the benzoic acid produced was transformed in to 3-phenylpropionic acid, When fully C-13-labelled acetic acid was fe d to the consortium, the labels were incorporated at the 1 and 2 posit ions of 3-phenylpropionic acid. When deuterium-labelled 3-phenylpropio nic acid was fed to the consortium, part of the phenylalanine of the b iomass was labelled, These metabolic transformations are reversible, s ince deuterium-labelled phenylalanine generated labelled 3-phenylpropi onic acid, Cinnamic acid was also transformed into 3-phenylpropionic a cid.