Some aspects of the phenylacetylcarbinol biosynthesis by Saccharomyces cerevisiae

The biosynthesis of phenylacetylcarbinol (PAC) by Saccharomyces cerevisiae in media containing benzaldehyde and fermentable sugars was studied under different experimental conditions. In shaking cultures with small volumes of medium a sigmoidal production curve for PAC was obtained. During the first and second part of the fermentation period (5 to 10 hours), the number of living yeast cells increased. In the third period (from the 10th to the 20th hour), the number of living yeast cells decreased rapidly. In agitated batch cultures the PAC produced during the first 5 hours of fermentation decreased only slowly on further incubation. In agitated but non aerated batch cultures, the PAC production increased rapidly, but the yields were much lower than in aerated batches. Acetone dried cells of baker's yeast produced PAC from benzaldehyde but no benzylalcohol. Besides PAC and acetylbenzoyl, a new biosynthetic product, trans-cinnam-aldehyde was determined.