INTRODUCTION OF FLOCCULATION INTO INDUSTRIAL YEAST, SACCHAROMYCES-CEREVISIAE SAKE, BY PROTOPLAST FUSION

Protoplast fusion was applied to obtain intraspecific fusion in yeast strains in order to overcome restrictions imposed by the natural matin g system. Acriflavine was used to construct petite mutants from non-fl occulent industrial Saccharomyces cerevisiae sake strain. UV radiation was used to construct ura(-) mutants from a respiratory competent and highly flocculent S. cerevisiae NCYC869 strain. Fusion products were selected by complementation on minimal medium. The frequency of appear ance of prototrophic hybrids was five per 10(5) protoplasts. The stabl e hybrids showed not only the S. cerevisiae sake characteristics but a lso flocculation ability, thereby confirming the success of the fusion .