250 ESSENTIALS OF BACTERIOLOGY 



Attenuation. If grown through successive generations, 

 it loses power to produce fermentation. 



Streptococcus Acidi Lactici (Grotenfeld) (1889). 

 Widely distributed in nature. 



Synonyms. Bacterium lactis acidi; Bad. Giintheri. 



Origin. In sour milk. 



Appearance. Very short cells, often as large as oval cocci, 

 in pairs or small chains, outer ends pointed. 



Properties. Immotile. Stain with Gram. Growth best 

 at 3 o-35 C. 



Growth. Facultative anaerobic. Delicate, opaque, re- 

 sembling dewdrops. Bouillon containing glucose grows 

 cloudy. Gelatin not liquefied. Milk coagulated. Strong 

 acid reaction. Curd is soft and easily mixed within twenty- 

 four hours. Gas is not formed. 



In lactose-agar stab no surface growth, but all along the 

 line. 



Potato. Scant growth. 



Origin. Almost always in sour milk, and the chief cause of 

 lactic acid formation. Found at times in combination with 

 B. acidi lactici and other bacteria. Sauer-kraut fermentation 

 is due to streptococcus of lactic acid and yeasts, the latter 

 producing gas. 



Bacterium Bulgaricum. 



Synonym. Bacterium caucasicus (v. Freudenreich). 



Origin. Present in milk. Thought to be a product of 

 eastern countries, but now recognized as universal. Arises 

 from alimentary tract. 



Properties. Produces large amount of acid at higher tem- 

 perature; non-motile. 



Form. Slender rods, 2 ju to 4 n long, tending to form 

 threads. 



Staining. Gram positive. 



Growth. Best growth at 40 C. Very meager colonies, 

 hardly visible. Curdling homogeneous, changed later into 

 soluble products. Gelatin not liquefied. Used to produce 

 artificial buttermilks. 



