SAKK YEAST (SA CCHAROMYCES SAKE 



223 



4. The sides and roofs of the koji cellars are covered with 

 matting of rice straw. 



5. In tlie preparation of moto the vessels are covered with 

 this matting-. 



6. Every year new matting must be made of fresh rice-straw ; 

 the renewing of these mats even takes place several times during 

 one and the same brewing season. 



Indeed, yeast identical with sake yeast was obtained upon 

 examination of the straw of the matting in the koji chamber of 

 the fresh rice straw taken from the fields, and even of the soil 

 of rice fields. Inoculations were made by transfering small chips 

 of the straw into sterilized Pastair s solution and preparing after 

 some time a gelatine plate from the yeast sediment formed. The 

 colonies of the sake )-east could easily be distinguis'-ed from 

 those of SaccJiaroviyccs viycodervia and of a small kind of )-east 

 somewhat resembling .S". e.vi^uiis ; colonies of mould-fungi and 

 bacteria were also present. Of the sake yeast thus obtained a 

 larger quantity was cultivated to enable exact comparisons to 

 be made."^ 



It is an interesting fact that in sake manufacture oJie kind of 

 yeast is principally observed although no[) recaution is taken to 

 avoid wild yeasts, as Saccharomyces apiculatiis , S. exiguns, etc. 

 In the first stage of the moto jirocess there is generally found also 

 a small kind of yeast, but later on this is no longer noticed to any' 

 notable extent. Also there occurs sometimes a development of 

 red kinds of yeast, which however are harmless. 



The sake yeast forms globular or slightly ellipsoidal cells of 

 5-9/^ in diameter, generally of 7 ji. In gemmation the cells 

 separate very soon and never form a larger connecting group like 

 the " top yeast " of the brewers. The yeast forms on gypsum-blocks 

 (tiever in tiie fermenting liquid) 1-2 ascospores, rarely three and 

 if so, the third is considerably smaller than the other two. A 

 previous good nutrition in liquids not too poor in nitrogen is 

 necessary to produce the spores.'^' I have cultivated this yeast, 

 obtained in pure culture with the usual methods, under various 

 conditions, e. g., upon sterilized potato and boiled rice with full 



(1) The investigations of Omori show that this saki yeast is a product ol a kind of 

 Ustilago frequently present in the rice fields. 



(2) I have, howevL-r, not proved that tiiese spore-like formations develop into new 

 ycast-cclls. 



