Degradation of phenylalanine and tyrosine by Sporobolomyces roseus

Abstract

Ammonia-lyase activity for L-phenylalanine, m-hydroxyphenylalanine and L-tyrosine was demonstrated in cell-free extracts of Sporobolomyces roseus. Cultures of this organism converted DL-[ring-C14]phenylalanine and L-[U-C14]tyrosine into the corresponding cinnamic acid. Tracer studies snowed that these compounds were further metabolized to [Cl4]protocatechuic acid. Benzoic acid and p-hydroxybenzoic acid were intermediates in this pathway. Washed cells of the organism readily utilized cinnamic acid, p-coumaric acid, caffeic acid, benzoic acid and p-hydroxybenzoic acid. Protocatechuic acid was the terminal aromatic compound formed during the metabolism of these compounds. The cells of S. roseus were able to convert m-coumaric acid into m-hydroxybenzoic acid, but the latter compound, which accumulated in the medium, was not further metabolized. 4-Hydroxycoumarin was identified as the product of o-coumaric acid metabolism by this organism.