Inhibition aspects of the bioconversion of L-phenylalanine to 2-phenylethanol by Saccharomyces cerevisiae

The inhibitory impacts of the bioconversion of L-phenylalanine (L-Phe) to 2-phenylethanol (PEA), a very important natural aroma compd., on the metab. of Saccharomyces cerevisiae Giv 2009 were investigated in batch and chemostat cultures. The bioconversion was found to be completely growth assocd. and lead to a maximal final PEA concn. of 3.8 g/l of PEA. This was attained in a fed-batch procedure on glucose in order to prevent the formation of ethanol, which generally reduced the final achievable PEA concn. by its synergistic inhibitory effect. Chemostat cultures revealed that the bioconversion uncoupled the catabolism from anabolism of S. cerevisiae esp. under oxidative growth conditions and thereby reduced the crit. diln. rate Dcrit. In addn., higher specific oxygen uptake rates qO2 were found in the presence of the bioconversion at oxidative growth than the maximal respiratory capacity qO2max found in continuous cultures without bioconversion. [on SciFinder (R)]