Cheese Bacteria. 



5. Neither gas formation nor coagulation, but slime formation is present, for 

 instance the Bacillus capsulatus, Bacillus viscosus, Bacillus capsulatus mucosus, Bacillus 

 lactis pituitosi, Bacterium ozacna. 



6. The tendril-shaped colony forming Bacillus aerogenes capsulatus. 



7. Without gas formation, but with liquefaction, for instance the Pneumobacillus 

 liquefaciens bovis. 



A decisive separation of these types cannot be strictly ac- 

 complished anywhere in the entire group. Each type has indi- 

 vidual or several representatives which show transitory tendencies 

 towards one or the other group, and the entire group is closely re- 

 lated to the colon aerogenes group, but in the latter, there are no 

 such pronounced lactic acid formations. The colon group is motile, 

 the aerogenes group non-motile. While the colon bacilli form indol 

 and split up proteids, these properties are absent in the aerogenes 

 group. Milk is coagulated with gas and acid formation, in which 

 the casein usually remains on the surface of the pressed-out serum 

 in the form of a spongy coagulum. The milk receives at the same 

 time an unpleasant, slightly offensive odor, and a salty, bitter taste. 

 Some varieties change the milk in this manner without the special 

 changes being perceptible. The several groups adapt themselves 

 very rapidly to their surrounding conditions, for instance to the 

 cultivation on cabbage or turnip media, and when transferred to 

 milk they impart to these the well-known changes of taste. 



Both bacteria are found in the intestines of sucklings 

 (Escherich). 



It is an important fact that most bacteria of this group are 

 destroyed in a short time at 65 deg. C., so that their occurrence 

 in pasteurized milk (in bottle pasteurization) may be an indication 

 that the heating to which the milk has been subjected was 

 insufficient. 



According to De Jong and Graaf some varieties of the colon 

 group resist heating to 70 deg. C. for a short time. 



The slender "cheese bacteria" of the third group of the lactic 

 acid producers are again divided into: 



1. Those coagulating milk with gas formation, for instance 

 Bacterium casei (Freudenreich), Bacillus caucasicus of Kefir 

 (Freudenreich) ; 



2. Those coagulating milk but with no gas formation; 



3. Those producing gas but no coagulation ; 



4. Those showing neither of these characteristics; 



5. Those producing slime; 



6. Those growing in tendril-shaped colonies. 



The bacteria of this third group are almost invariably non- 

 motile, and sporeless, mostly without capsules. They are Gram- 

 positive. The fermentation of sugar varies. In milk they mostly 

 form levo-rotary lactic acid, while the other two varieties are rarely 

 produced. Some peptonize proteids ; their growth is favored more 

 by aerobic than by anaerobic conditions. 



