Diacetyl content reduction in industrial brewer's yeast through ILV2 disruption and BDH1 expression

Diacetyl is crucial to beer maturation because of its characteristic buttery taste. New industrial brewer's yeast strains, including single ILV2 allele disruption (QI2), single ILV2 allele disruption and BDH1 overexpression (QI2GB1), and BDH1 overexpression (B1Y), were constructed by disrupting the gene (ILV2) involved in a-acetolactate synthesis and introducing the diacetyl reductase gene (BDH1). The diacetyl content and fermentation performance of the three recombinant strains were examined and compared. Results showed that the diacetyl concentration in QI2, QI2GB1, and B1Y decreased by 17.83, 28.26, and 9.57 %, respectively, compared with that in the host strain S2. The fermentation ability in terms of fermentation degree and major flavors yield of the three recombinant strains was similar to that of the host. This study may serve as a reference for the brewing industry and for research on diacetyl reduction.