Waksman 



64 



Actinomycetes 



upon bacteria. They reported, however, that the lytic factor of actino- 

 mycetes was highly specific, since it had no efi^ect upon other species 

 or even upon other strains of the same species of actinomyces. When 

 growth of the organism was delayed under the influence of various fac- 

 tors or when the culture became aged, lysis took place. Different cul- 

 tures underwent lysis with varying degrees of rapidity. It was assumed, 

 therefore, that production of the lytic factor or its mode of action dif- 

 fered with the various organisms. At temperatures of 60° to 70°C., 

 lysis occurred in a few minutes. The lytic agent was resistant to a 



Fig. 16.— Method of measuring actinophage concentration Qfrom Reilly, Harris 

 and Waksman, 355). 



temperature of 80 °C. for 1 hour but was destroved at 100°C. in 5 

 minutes. Not only the living but also the dead cells of the organism 

 were affected by the lytic agent. This last suggested that the agent 

 is different in its action from that of true phage. 



With the discover)^ that the streptomycin-producing strains of S. 

 griseus are subject to attack by a virus or a phage-like agent, the problem 

 of phage action upon actinomycetes entered a new phase. The lysis 

 of the actinomyces produced by the phage appeared to be quite distinct 

 from the lytic phenomena. 



Saudek and Colingsworth (383) were the first to report that S. 

 griseus is subject to the action of a transmissible lytic agent which had 



