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

Aims: The biotransformation of L-phenylalanine into benzaldehyde (bitter al mond aroma) was studied in the strain Trametes suaveolens CBS 334.85. Methods and Results: Cultures of this fungus were carried out in the absenc e or in the presence of HP20 resin, a highly selective adsorbent for aromat ic compounds. For the identification of the main catabolic pathways of L-ph enylalanine, a control medium (without L-phenylalanine) was supplemented wi th 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 larg e amounts of 3-phenyl-1-propanol, benzyl and p-hydroxybenzyl alcohols as th e products of both cinnamate and phenylpyruvate pathways. Conclusions: The addition of HP20 resin, made it possible to direct the cat abolism of L- phenylalanine to benzaldehyde, the desired target compound, a nd to trap it before its transformation into benzyl alcohol. In these condi tions, 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 potenti al 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.