Yeast YIp\|type expression recombinant plasmid(pCMA2\|1) was constructed. The expression of α\|acetolactate decarboxylase gene from \%Bacillus subtilis\% was controled by \%CUP1\% promoter and its own terminator. The recombinant plasmid pCMA2\|1 was introduced into the brewer’s yeast PJ3\|5. Transformants were selected using copper resistance as selected marker. The results of activity assay showed that PJ3\|5 didn’t produce α\|acetolactate decarboxylase(ALDC), where as the activity of α\|ALDC in transformants were induced by copper sulfate. The laboratory scale fermentation test confirmed that the total diacetyl concentration was reduced effectively by α\|ALDC in transformant.
