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BACILLUS ACIDI LACTICI. Hueppe. 



BACILLUS OF LACTIC ACID FERMENTATION. IS ONLY ONE OF A LARGE 

 NUMBER OF BACTERIA GIVING RISE TO LACTIC ACID. 



Origin. Sour milk. 



Form. Short, thick rods, about one-half as long as 

 long as wide; usually in pairs, rarely in chains. 



Motility. Has no motion. Brownian movement, 

 however, is marked. 



Sporulation. Hound, terminal spores observed. 



Anilin Dyes. Stain readily. 



Growth. Abundant and fairly rapid. 



Gelatin Plates. The deep colonies are round or oval, yellow, sharp bor- 

 dered, finely granular. The surface colonies spread, forming thin plaques, 

 with irregular, wavy borders. The outer zone of the colony is at first almost 

 transparent and shows markings resembling the venation of leaves. 



Stich Cultures. Slight growth along the stich, but on the surface it is 

 considerable and spreads rapMly as in thin, dry, pearly-white covering. In 

 old cultures bundles of crystals form along the stich at or near the surface. 



Streak Cultures. On agar, forms a grayish white, moist, spreading 

 growth, which offers no. special characteristics. On potatoes, it forms a 

 brownish yellow, slimy covering. 



31Wc. In sterilized milk converts the lactose or milk-sugar into lactic 

 acid and carbonic acid. The acid reaction thus produced causes a precipita- 

 tion of the casein or curd. This change occurs only in presence of air. 



Oxygen requirements. Is a facultative anaerobe. 

 Temperature. Grows between 10 and 45. Opti- 

 mum about 350. 



Behavior to Gelatin. Not liquefied. 



Aerogenesis. Gas is produced in milk. 



Pathogenesis. No effect. 0.75 per cent, lactic acid 

 stops the growth. Production of lactic acid in the mouth 

 and dental caries ; abnormal fermentations in the stomach, 

 in the intestines. Lactic acid bacteria favor the growth 

 of anaerobic bacteria. 



