L-phenylacetylcarbinol production by yeast petite mutants

The yeast Saccharomyces cerevisiae is able to biotransform benzaldehyde into L-phenylacetylcarbinol (L-PAC), a key intermediate in the production of ephedrine and pseudoephedrine, by the action of pyruvate decarobxylase (PDC) enzyme. This biotransformation can alternatively be performed by acetohydroxyacid synthase (AHAS) which is a mitochondrial enzyme. In the yeast petite mutants, AHAS accumulates in the cytosol. In the current study, wild-type yeast cells and yeast petite mutants were examined for L-PAC biosynthesis. The results showed higher L-PAC titers in the yeast petite mutants. In addition, the effect of cell immobilization and carbon source (glucose or molasses) on L-PAC production was investigated. It was found that cell immobilization enhances L-PAC formation. The highest L-PAC concentration (2.4 g/l) was obtained at 2 g/l of benzaldehyde using the immobilized petite mutants grown on molasses.