To improve ethanol production capability, a flocculent yeast,
Saccharomyces cerevisiae TJ1, was hybridized with other high-alcohol producing strains by protoplast fusion. A fusant strain of strain TJ1 hybridized with an Awamori-brewing strain, N1, produced 12.4 (w/v)% of ethanol even at 40°C. The fusant showed good flocculence and good sedimentation. In a repeated batch culture with cell reuse at 37°C, an average productivity of 13 g/
·h was attained.