264 



BACTERIOLOGICAL CHEMISTRY 



of fermentation is constant, and is controlled by the 

 supply of inorganic phosphate derived from the hexose 

 phosphate esters by the action of the enzyme phosphatase. 

 The inorganic phosphate so formed esterifies more sugar, 

 which is fermented with liberation of the phosphate again. 

 There is no accumulation of phosphate esters nor of 

 inorganic phosphate, and the reaction proceeds at a con- 

 stant rate until all the sugar has been fermented, at 

 which stage inorganic phosphate is finally set free and the 

 sugar of the esters fermented. 



If inorganic phosphate is added to such a fermenting 

 mixture the velocity of fermentation increases temporarily, 



20 



15 ' 



10 



10 



20 30 



Minutes 



40 



— >- 



Fig. 7 {Ajtev Harden) 



due to the increased formation of the fermentable ester 

 which accumulates until all the added inorganic phosphate 

 has been converted to ester, after which the rate falls 

 back to the normal value, depending on the rate of 

 hydrolysis of the ester. Curve (2) in Fig. 7 shows this 

 effect. 



