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

Abstract

Aims: The biotransformation of L-phenylalanine into benzaldehyde (bitter almond aroma) was studied in the strain Trametes suaveolens CBS 334.85.

Methods and results: 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.

Conclusion: 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%.

Significance and impact of the study: 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.