Biotransformation of benzaldehyde into (R)-phenylacetylcarbinol by filamentous fungi or their extracts

Extracts of 14 filamentous fungi were examined regarding their potential fo r production of (R)-phenylacetylcarbinol [(R)-PAC], which is the chiral pre cursor in the manufacture of the pharmaceuticals ephedrine and pseudoephedr ine. Benzaldehyde and pyruvate were transformed at a scale of 1.2 ml into P AC by cell-free extracts of all selected strains, covering the broad taxono mic spectrum of Ascomycota, Zygomycota and Basidiomycota. Highest final PAC concentrations were obtained with the extracts of Rhizopus javanicus and F usarium sp. [78-84 mM (11.7-12.6 g/l) PAC within 20 h from initial substrat e concentrations of 100 mM benzaldehyde and 150 mM pyruvate]. (R)-PAC was i n about 90-93% enantiomeric excess. Rhizopus javanicus had the advantage of faster growth than Fusarium sp. Rhizopus javanicus mycelia were used as an example in a biotransformation process based on whole cells and benzaldehy de and glucose as substrates. The substrate pyruvate was generated through the fungal fermentation of glucose. Only 19 mM PAC (2.9 g/l) were produced within 8 h from 80 mM benzaldehyde, with evidence of significant benzyl alc ohol production.