224 



ON THE OKIGIN OF SAKE YEAST. 



access of sterilized air, but never observed anything like a myce- 

 lium ; the cells preserved their form, whether they had been 

 obtained from fermenting moto or directly from the rice straw. 



The sake yeast still exhibits considerable fermenting energy 

 in presence of 12 per cent, alcohol, but at 16 per cent it is very 

 feeble. In a 10 per cent, sugar solution containing various propor- 

 tions of alcohol, after six days only 0.1%' sugar was found when 

 alcohol amounted to 4^ ; 5.46_%' sugar at 12% alcohol, and 8.64% 

 at 16% alcohol. In regard to the higher alcohols I observed 

 thai the development and fermentation is stopped by ^% propylic, 

 ^% isobutylic, \% amylic and 0.$% caprylic alcohol. 



Cane sugar solutions can, in presence of some meat extract, 

 be fermented by sake yeast, even in concentrations as high as 45 

 per cent., but the action sets in later. The presence of as much as 

 6 per cent, sodium chloride does not essentially interfere with the 

 fermentation of a 10% cane sugar nourishing solution, while lO^ 

 sodium chloride depresses the fermenting energy by nearly one 

 half and 22% stops it entirely. 



In a mixture of 10% cane sugar and 4% tartaric acid, in 

 which the so-called " wild " yeasts still show development, neither 

 sake yeast from the juoto mash nor that directly from the rice 

 fields showed any sign of development within four weeks ; this 

 yeast behaves, therefore, like beer yeast, to which indeed it has 

 a close resemblance. 



In this connection it may be mentioned that in Japan some 

 kinds of vegetable cheese, as 7mtto and tama-miso are also 

 ripened and influenced by microbes of rice straw. The fungi on 

 the rice straw i.e. from swampy and heavily manured rice fields 

 also play a role in the manufacture of arrac in Java. Crushed 

 rice wrapped in rice straw for three days represents the so-called 

 ragi, something similar to our koji. The diastase-yielding 

 fungus, as well as the yeast, (5. Vorderinanni) is also derived from 

 the rice fields. 



(i)Cf. my investigation on Natto, Bullet, of the College of Agriculture II, Xo. 2. 



