482 MANUAL OF MILK PRODUCTS 



When milk containing bacteria of this type is held under 

 conditions favorable to its growth, the acid produced will 

 inhibit other forms and the milk will eventually become a 

 practically pure culture of the Bacillus bulgaricus. There can 

 be no question that, under conditions favorable to its growth, 

 this bacterium is able to suppress very effectively other kinds 

 of bacteria, even many of those which produce an acid fermen- 

 tation. This is well illustrated in the manufacture of cheese 

 of the Emmental or Swiss type. Cheese made by this method 

 from milk containing gas-forming bacteria will become filled 

 with gas bubbles in the press. If a comparatively small 

 amount of a culture of the Bacillus bulgaricus is added to this 

 milk, the high temperature at which the cheese is held promotes 

 its vigorous development, and the gas formers are completely 

 suppressed. 



There is little doubt that if this organism could be estab- 

 lished in the large intestine under conditions favorable to its 

 growth it would soon produce a state of affairs which would at 

 least inhibit the growth of the bacteria that usually decompose 

 the proteins. The evidence that this takes place, even when 

 large quantities of the bacteria are ingested, is by no means 

 conclusive. On the one side the associates of Metchnikoff 

 have produced considerable evidence to show that when B. 

 bulgaricus is taken into the digestive system it becomes estab- 

 lished in the intestines, where it persists for some time after 

 the feeding ceases. Cohendy, who fed four patients for ex- 

 tended periods on milk curdled with B. bulgaricus, concluded 

 that this organism was readily established in the intestines, 

 and that it persisted there for a considerable time after the 

 subject had ceased to take fermented milk. This was said to 

 be especially true if a diet containing suitable nourishment for 

 the ingested organism was adopted. It is stated that the mul- 

 tiplication of these bacteria took place in the upper two-thirds 

 of the colon. The stools were acid or neutral. 



