Beer brewing using a fusant between a sake yeast and a brewer's yeast

Beer brewing using a fusant between a sake yeast (a lysine auxotrophic muta nt of sake yeast K-14) and a brewer's yeast (a respiratory-deficient mutant of the top fermentation yeast NCYC1333) was performed to take advantage of the beneficial characteristics of sake yeasts, i.e., the high productivity of esters, high tolerance to ethanol, and high osmotolerance. The fusant ( F-32) obtained was different from the parental yeasts regarding, for exampl e, the assimilation of carbon sources and tolerance to ethanol. A brewing t rial with the fusant was carried out using a 100-l pilot-scale plant. The f usant fermented wort more rapidly than the parental brewer's yeast. However , the sedimentation capacity of the fusant was relatively low. The beer bre wed using the fusant contained more ethanol and esters compared to that bre wed using the parental brewer's yeast. The fusant also obtained osmotoleran ce in the fermentation of maltose and fermented high-gravity wort well.