ENERGY SUPPLY OF THE CELL 



113 



continued small amount of fermentation at very high 

 concentrations is obvious. 



Table 17. — Rate of Lactic Fermentation per Hour 

 (By 420,000,000 cells of Lad. acidophilus per cubic centimeter) 



SUMMARY OF FACTS 



The rate of fermentation decreases with the age of the 

 culture. If sufficient substrate is available, the decrease 

 in the rate is caused by the fermentation products. 

 Addition of these to a rapidly fermenting culture will 

 decrease the rate of fermentation. 



If the added fermentation products are as high as the 

 limiting concentration, there still seems to take place a 

 slow but noticeable fermentation provided that the 

 number of fermenting cells is very large. 



SUMMARY OF THEORIES 



The retardation of a fermentation by its own products 

 has been expressed in a simple formula on the assumption 

 that the decrease of the rate of fermentation is propor- 

 tional to the concentration of products divided by the 

 limiting concentration; in other words, the decrease is 

 proportional to the products already formed, expressed 

 in terms of the total possible products. 



This assumption leads to a formula for a '^ fermentation 

 constant" representing the rate of fermentation corrected 



