1. IntroductionIn bacterial and yea

1. Introduction
In bacterial and yeast systems, pyruvate is readily decarboxylated and the resulting hydroxyethyl- thiamin
diphosphate carbanion couples to benzaldehyde to generate (L)-phenylacetylcarbinol (L-PAC), which is
the commercial precursor to ephedrine (Meyer et al., 2011).The L-PAC production is catalyzed by pyruvate
decarboxylase (PDC) and is associated with by-product formation, viz. benzyl alcohol, due to the activity of
an alcohol dehydrogenase (ADH) and/or oxidoreductases (Figure 1). Some traces of benzoic acid as a byproduct
have also been reported (Khan and Daugulis, 2011). L-PAC can be produced by chemical
synthesis from cyanohydrins (Brusse et al., 1988; Jackson et al., 1990) but the biotransformation route
from benzaldehyde is preferred industrially.