120 PHYSIOLOGY OF BACTERIA 



At20°C rate = A^o 



At 21°C rate = KoQi 



At 22°C rate = (i^oQi)Qi = KoQi^ 



At 23°C rate = KoQi' 



At 30°C rate = KoQi^^ 



The temperature coefficient for 10°C. increase equals the temperature 

 coefficient for 1°C. increase raised to the 10th power. 



Qio = Oi 



10 



For any temperature interval AT, Qio can be found from the formula 



AT 



«■« = yji^) 



10 



The van t'Koff formula shows that the temperature coefficient 

 is not really constant. The expression 



^1- To 

 T,To 



will be different at different temperatures. If Qio = 2.0 at 20 to 

 30°C., it must change as follows: 



Qio between and 10°C. = 2.218; A = 6153; /x = 12306 

 20 and 30°C. = 2.000; A = 6153; m = 12306 

 40 and 50°C. = 1.838; A = 6153; ju = 12306 

 90 and 100°C. = 1.575; A = 6153; /x = 12306 



In fact, at the absolute zero, at — 273°C., Qio = infinite, and at very 

 high temperatures, Qio approaches 1. 



The van t'Hoff equation may be written in the form of a differential 

 equation: 



d\nK fi_ 



dT 2T2 



Upon integration between the limits Ti and T2, the van t'Hoff formula 

 is obtained, with fi = 2A. The general integration yields the 

 equation 



lnX= -^ + C 



