Novel sucrose unassimilating flocculent yeast

Abstract

An object of the present invention is to provide a sucrose unassimilating yeast which has a flocculation ability and has much of a proven performance of food production. The present invention pertains to a yeast strain expressed by accession number: NITE BP-1587.

1 .  Saccharomyces cerevisiae  strain NITE BP-1588. 
     
     
         2 . The  Saccharomyces cerevisiae  strain according to  claim 1 , wherein the strain is employed for a method of producing sugar and ethanol comprising a step of fermenting sugar liquid derived from a plant with yeast. 
     
     
         3 . The  Saccharomyces cerevisiae  strain according to  claim 1 , wherein the strain is employed for a method of producing sugar and ethanol comprising steps of:
 removing non-sugar components contained in sugar liquid derived from a plant to clarify the sugar liquid; and   adding yeast to the clarified sugar liquid to carry out ethanol fermentation at a given temperature under an anaerobic condition for an appropriate length of time.   
     
     
         4 . A method of producing sugar and ethanol comprising a step of fermenting sugar liquid derived from a plant with the  Saccharomyces cerevisiae  strain according to  claim 1 . 
     
     
         5 . A method of producing sugar and ethanol comprising steps of: removing non-sugar components contained in sugar liquid derived from a plant to clarify the sugar liquid; and
 adding the  Saccharomyces cerevisiae  strain according to  claim 1  to the clarified sugar liquid to carry out ethanol fermentation at a given temperature under an anaerobic condition for an appropriate length of time.   
     
     
         6 .  Saccharomyces cerevisiae  strain NITE BP-1587 obtained by a breeding method comprising:
 subjecting a yeast strain deposited under accession number NBRC 10055 and a yeast strain deposited accession number NITE BP-1589 to spore isolation to acquire an isolated spore showing type a or type a as a mating type;   mating the isolated spore of the yeast strain deposited under accession number NBRC 10055 and the isolated spore of yeast strain deposited under accession number NITE BP-1589 which have different mating types to create a mated strain;   carrying out, as for the created mated strain, tetrad dissection to acquire an isolated spore; and   screening the obtained isolated spore to select the  Saccharomyces cerevisiae  yeast strain and having a character of a sucrose unassimilating property and flocculation.   
     
     
         7 .  Saccharomyces cerevisiae  strain obtained by diploidizing the  Saccharomyces cerevisiae  strain according to  claim 6 . 
     
     
         8 . A method of breeding a  Saccharomyces cerevisiae  yeast strain comprising: subjecting a yeast strain deposited under accession number NBRC 10055 and a yeast strain deposited under accession number NITE BP-1589 to spore isolation to acquire an isolated spore showing type a or type a as a mating type;
 mating the isolated spore of the yeast strain deposited under accession number NBRC 10055 and the isolated spore of the yeast strain deposited under accession number NITE BP-1589 which have different mating types to create a mated strain;   carrying out, as for the created mated strain, tetrad dissection to acquire an isolated spore; and   screening the obtained isolated spore to select the  Saccharomyces cerevisiae  yeast strain and having characters of a sucrose unassimilating property and flocculation.   
     
     
         9 . A method of breeding a yeast strain according to  claim 8 , further comprising: diploidizing the obtained  Saccharomyces cerevisiae  yeast strain.