On the Vegetable Cheese, Natto, 



BY 



K- Yabe, Nogakushi. 



Since remote times there has been prepared in Japan from 

 soya beans, a sort of vegetable cheese called natto. The beans 

 are first boiled in water for five hours to render them exceedingly 

 soft. The still hot mass is in small portions wrapped in straw 

 and the bundles thus formed, well tied at both ends, are then 

 placed in a cellar, in the middle of which a fire is kindled, 

 whereupon the cellar is well closed. The heat is left to act 

 for twenty-four hours, after which the product is ready for con- 

 sumption. Although the moderate heat of the cellar acts only 

 for twenty-four hours, there is still a considerable bacterial 

 change going on. The microbes may be derived either from 

 the air or from the straw. Of course it can not be expected 

 that bacteria on the surface of the soya beans would still be 

 very active. They are probably killed by the five hour's 

 boiling. Z) This product has a peculiar but not putrid smell. 

 The soft mass of the beans is kept together by a very thick 

 viscid substance. In this substance I have found four kinds of 

 microbes present, and the chemical decomposition of proteids 

 must be due to one or more of these microbes. 



1. The Microbes of Natto. 



A trace of the viscid liquid of the cheese was inoculated in 

 a gelatine solution and a plate culture was prepared. After a 

 few days numerous colonies (1260) appeared, of which four 

 different kinds could be observed, and of these were prepared 

 pure cultures. Three of these different cultures were formed by 

 micrococci, and one by a small, not motile, bacillus liquifying 



1) Exceptional cases where bacteria can stand boiling heat still longer are 

 known, for instance with Bacillus subtilis. 



