Shifting the biotransformation pathways of L-phenylalanine into benzaldehyde by Trametes suaveolens CBS 334.85 using HP20 resin.

Abstract

The biotransformation of L-phenylalanine into benzaldehyde (bitter almond aroma) was studied in the strain Trametes suaveolens CBS 334.85. Cultures of this fungus were carried out in the absence or in the presence of HP20 resin, a highly selective adsorbent for aromatic compounds. For the identification of the main catabolic pathways of L-phenylalanine, a control medium (without L-phenylalanine) was supplemented with each of the aromatic compounds, previously detected in the culture broth, as precursors. Trametes suaveolens CBS 334.85 was shown to biosynthesize benzyl and p-hydroxybenzyl derivatives, particularly benzaldehyde, and large amounts of 3-phenyl-1-propanol, benzyl and p-hydroxybenzyl alcohols as the products of both cinnamate and phenylpyruvate pathways. The addition of HP20 resin, made it possible to direct the catabolism of L- phenylalanine to benzaldehyde, the desired target compound, and to trap it before its transformation into benzyl alcohol. In these conditions, benzaldehyde production was increased 21-fold, from 33 to 710 mg l-1 corresponding to a molar yield of 31%. These results showed the good potential of Trametes suaveolens as a biotechnological agent to synthesize natural benzaldehyde which is one of the most important aromatic aldehydes used in the flavour industry.