Construction of new alpha -galactosidase producing yeast strains and the industrial application of these strains

摘要

The objects of this invention are new Saccharomyces cerevisiae yeast strains into which alpha -galactosidase gene (MEL+) has been transferred by using recombinant DNA methods. Baker's and distiller's yeasts producing alpha -galactosidase, are utilizable in the corresponding industry, because they are able to utilize the raffinose present in molasses, which results in greater yield of yeast (or ethanol) and reduction or elimination of the costs associated with biological oxygen demand (B.O.D.) in the effluent from factories. The improved ability of brewer's yeasts to produce alpha -galactosidase provides a sensitive method for monitoring pasteurization of beer. The new yeast strains prepared by using recombinant DNA methods produce more alpha -galactosidase than naturally occurring alpha -galactosidase producing yeast strains. Also methods for marking yeast strains and for producing stable transformants of yeasts are presented.