1 38 BACTERIOPHAGES 



under conditions in which adsorption is reversible, depending on 

 whether the mixture is diluted or not before centrifugation. 



1. Kinetics of Adsorption 



Krueger (1931) investigated the adsorption of a phage to liv- 

 ing and heat-killed staphylococci. He found that with an excess 

 of bacteria, the adsorption follows the kinetics of a first-order 

 reaction. The rate of adsorption is 



-dP/dt = kBP (1) 



in which k is the velocity constant, B is the bacterial concentra- 

 tion, and P is the phage concentration. The appropriate solu- 

 tion yields 



^ = ^log^ (2) 



in which Pq is the concentration of unadsorbed phage at the 

 beginning, and P at the end, of the time interval t. 



Krueger found k to be 2.4 X 10"!" ml. per minute either with 

 living or heat-killed bacteria. 



Equations (1) and (2) are generally applicable to adsorption of 

 phage, as indicated by further work described below. In them 

 B can be considered constant provided the ratio of phage to bac- 

 teria is kept sufficiently low so that the bacterial surfaces remain 

 effectively unaltered. This explains why the two-body inter- 

 action can be described by first-order kinetics. 



Krueger (1931) also attempted to study adsorption-equilib- 

 rium with results that are not now interpretable owing to 

 ambiguities of his assay method (Chapter III). 



A very extensive study of phage adsorption was made by 

 Schlesinger (1932a) using coliphage WLL. This phage was re- 

 ported by Burnet (1934a) to be related to phage CI 6 and hence 

 is also related to T2. The bacterium used was E. coli 88, either 

 as a broth culture of living cells, or as a cell suspension killed by 

 heating at 70 ° C. for one hour. Adsorption was carried out at 

 37 ° C. In these experiments the amount of unadsorbed phage 



