134 



PHYSIOLOGY OF BACTERIA 



ferred to the cold medium. The author has tested the 

 minimum temperature of fermentation of streptococci 

 by transfering the centrifuged bacteria from 250 c.c. of 

 a full-grown lactose broth culture to 150 c.c. of sterile 

 milk, after both milk and bacteria had been cooled to 

 the temperature of the experiment. The acid produced 

 by these bacteria is given in Table 26. 



Table 26. — Lactic Acid Produced in Milk by Large Numbers of 



Cells 

 (Strept. cremoris No. 23) 



{Strept. lactis) 



All three streptococci produced acid at -|-5.5°C. and 

 even at — 1°C. Strept. lactis and Strept. cremoris 23 multi- 

 plied at 5.5°C. if inoculated into milk in small numbers, 

 at the rate of about one generation in from twenty-four 

 to forty-eight hours; Strept. cremoris 18 did not multiply. 



