On the Behaviour of Yeast at a High Temperature, 



BY 



T. Nakamura, NogakusM. 



It is a well-known fact that certain bacteria can be deprived 

 of their fermenting power without their life being" otherwise 

 impaired ; though in this case they lead only an aerobic existence. 

 It seemed to me of some interest to study closely also living 

 yeast deprived of its fermenting power. 



At the same time I wished to collect some imforniation about 

 the maximum of temperature which yeast can resist for sonic time. 

 Numerous observations have been made on this point, but they 

 do not agree w'ell, as the time of exposure to the high tempera- 

 ture was not always taken into account, and pure-cultures free 

 Irom ascospores were not selected for such experiments. 



When the time of exposure is but short, the noxious effects 

 will be less marked at the same high temperature tlian during a 

 longer exposure. Kayser observed with some varieties of yeast 

 a resisting power at 6o° when heated (in the moist state) for only 

 five minutes. In the dry state the cells were not even killed at 85°, 

 some varieties resisted even 100°. Other authors state that 

 ordinary beer-yeast loses its power of fermentation at 40° while 

 the cells are killed at 70°. Schitt.zeiibergcr, again, states that the 

 temperature of 53° is the highest that yeast can resist. 



