USE OF A MODIFIED ALCOHOL-DEHYDROGENASE, ADH1, PROMOTER IN CONSTRUCTION OF DIACETYL NONPRODUCING BREWERS-YEAST

The bacterial gene, encoding alpha-acetolactate decarboxylase (alpha-A LDC), was expressed in a bottom-fermenting brewer's yeast under the co ntrol of a modified Saccharomyces cerevisiae alcohol dehydrogenase (AD HI) promoter which lacks the upstream regions from -800 bp to -1500 bp . In pilot scale brewing conditions, the level of alpha-ALDC produced was high enough to reduce the concentration of diacetyl so that lageri ng was not required. alpha-ALDC active brewer's yeast strains were als o shown to be suitable for high gravity brewing.