Waksman — 102 — Actinomycetes 



added to soil infected Phytoinonas tahaci protected the plants against in- 

 fection. The importance of such lytic agents in soil processes and their 

 relation to true antibiotics are matters for further investigation. 



The ability to coagulate milk and to dissolve the coagulum is also 

 a common property of actinomycetes. Whether this is due to the for- 

 mation of a special enzyme of the nature of rennet or lab or whether 

 it is a property of the proteolytic mechanism of the organisms remains 

 to be determined. 



Many strains of actinomycetes are able to hemolyze blood cells, as 

 a result of production of hemolysins. These enzyme systems are dis- 

 tinct from the true proteolytic enzymes, and are also fairly resistant to 

 heat. They apparently have no relation to the pathogenic properties of 

 the organisms producing them. 



Table 19: Distribution of bacteriolytic properties among actinomycetes C503); — 



The species of Nocardia are usually much weaker proteolytic forms 

 than the Streptomyces species. Some of the nocardias, notably the red 

 and green types, do not liquefy gelatin at all. This is true of N. aster- 

 oides, an important pathogen, and of the saprophytic N. riiber, N. 

 viridis, and others. Some of the yellow species (N. (lava) are weak 

 liquefiers. The lemon-yellow forms (N. citrea) and the white types 

 (N. alhd), however, liquefy gelatin energetically. 



While the proteolytic property of actinomycetes is a constant char- 

 acteristic, it is essential to remember that the occurrence and the rate 

 of proteolysis, as measured by the extent and rapidity of the reaction, 

 are influenced by environment and are variable properties. 



Although no enzyme preparations comparable to those of certain 

 fungi and bacteria are obtained on a large scale from actinomycetes, 

 there is no doubt that such preparations could easily be obtained. 

 Whether they would have any distinct advantages is hard to tell. 

 Possibly the thermophilic capacity of some of the organisms might yield 

 enzymes which would be more heat-tolerant than those produced by 

 fungi and bacteria. 



