On the Origin ot Sake Yeast (Saccharomyces Sake). 



K. Yabe, Ndgnkus/ii. 



The source ot the sakcyavst which rapidly develops during the 

 first stage of sake maiuifacture, called vioto, has repeatedly been 

 a subject of discussion and even at the present day is considered 

 an open question. Korsclielt first propounded'" the hypothesis 

 that the mycelium of the same fungus that brings on the sacchari- 

 fication of the mash, is the source looked for, and believed that 

 this case is analogous to that of Mucor racemosus. But 

 Atkinsoif^^ soon afterwards expressed his doubts on this point. 

 He says : " It is, of course, a matter of great difficulty to prove 

 any preposition of this kind, but probability appears to my mind 

 to be greatly in favour of the hypothesis that the germs have been 

 either air-sown or were adherent to the grains of koji before use." 



Indeed, a series of experiments which I have made, i)artly in 

 conjunction with Prof. Kozai, have placed beyond doubt, that 

 the mycelium fungus in question, Aspergillus oryzae, is entirely 

 incapable of yielding yeast cells. I have prepared pure cultures 

 in the usual way and cultivated the pure fungus under a series 

 of very different conditions, in absence and in presence of air, of 

 good and poor nutrients, but never could detect the formation of 

 yeast cells."' Sometimes, however, the cells became somewhat 

 deformed in absence of air (growth was never observed under this 

 condition) and when thus kept in Pasteur s solution for 3-4 weeks 

 showed small bright globules, which were neither fat nor 

 glycogen, but very probably consisted of a peculiar proteid. 



(1) Mitthg. D. Ges. f. Ostasien, Tokyo 1878. 



(2) The Chemistry of Sake Brewing, Tokyo 1881. 



(3) The investigations of Atkinson and those of Kellncr, Nagaokn and lifori have 

 demonstrated the powerful action of the diastase and invertase of this fungus. 

 I may here mention, however, that mannan prepared from the root of Ainorpho- 

 phallus konjak is not at all attacked by the enzymes of this fungus ; although a rich 

 vegetation of this fungus was in contact with that gelatinised carbohydrate for three 

 weeks, no liquefaction, no formation of mannose was noticed. 



