Waksman — 62 — Actinomycetes 



activated when the culture is heated to 100°, but not to 80°, for 5 

 minutes. 



The lytic factor of actinomycetes is very specific. It does not act 

 upon other species or even on closely related forms. It is not to be 

 confused with the transmissible or phage factor which affects certain 

 actinomycetes. In contrast to actinophage, the lytic agent acts also 

 upon the dead cells of the organism. 



A thermophilic actinomyces isolated (207) from composts of horse 

 manure was found to grow well on various media, but it underwent 

 lysis when grown in a synthetic medium containing ammonium sul- 

 fate and starch, after 24 to 48 hours' incubation at 50°C. During 

 growth, the pH of the culture changed from 7.0 to 5.7. The addition 

 of CaCOs to the medium prevented the production of acid as well as 

 of lysis. 



After maximum growth has been attained, S, griseus, the organism 

 that produces streptomycin, undergoes lysis (395). This takes place 

 more rapidly under submerged than under stationary conditions of 

 cultivation. The whole culture tends to become viscous as a result 

 of formation of the lysed material. Apparently the maximum peak of 

 streptomycin production is associated with the setting in of lysis of the 

 culture. When lysis has progressed too far, production of streptomycin 

 ceases, and even that already produced may be destroyed. 



Dmitrieff and Souteeff (91) observed that a culture of an or- 

 ganism designated as Actinomyces hovis, and which evidently belonged 

 to the genus Streptomyces, underwent lysis in various media. When 

 the organism was grown on agar media, the production of lysis was 

 found to be associated only with the formation of a certain t)'pe of 

 colony. As a result of lysis, two types of daughter colonies were 

 formed: one was similar to the mother colony and was characterized by 

 capacity for lysis; the other type of colony did not lyse and was morpho- 

 logically different from the first. The cultures that originated from the 

 colonies capable of undergoing lysis were strongly proteolytic and did 

 not form any aerial mycelium. The cultures obtained from nonlysing 

 colonies were less proteolytic and produced a chalky aerial mycelium, 

 which changed the reaction of litmus milk to alkaline. In broth cul- 

 tures, lysis took place in 2 to 3 weeks; it was associated with the living 

 organism and was of the nature of a nonenzymatic and nontransmissi- 

 ble lytic factor. 



These results are comparable to those obtained later by Schatz and 

 Waksman (395) in the production of inactive strains by S. grisetis. 

 These strains were free of aerial mycelium, produced no streptomycin, 

 underwent much more rapid lysis, and formed much more acid in the 

 medium (Table 5). 



Effect of actinophage upon actinomycetes.— VJiu^oi.^ and WiE- 

 RiNGA (509) observed that cultures of actinomycetes isolated from in- 

 fected potatoes underwent lysis. This phenomenon was ascribed to the 



