ANTAGONISTIC PROPERTIES 113 



ture of a white actinomyces developed on the plates, each colony being 

 surrounded by a clear zone of dissolved bacterial cells. By transferring 

 this culture to a suspension of dead staphylococci in sterile saline, a 

 characteristic flaky growth was produced, the bacterial suspension be- 

 coming clarified in 36 hours. When the lysed emulsion was filtered, the 

 filtrate could again dissolve a fresh suspension of dead staphylococci. 

 This culture was found able to attack all staphylococci tested as well as 

 certain gram-negative bacteria, such as Ps. aeruginosa; however, it was 

 inactive against M. tuberculosis and E. coli. Some antagonistic strains 

 could also attack E. coli, though this property was readily lost. 



This type of antagonism was believed to be widely distributed in na- 

 ture and to be directed against many bacteria, pathogenic and sapro- 

 phytic. The culture of the antagonist in bouillon gave a very active 

 agent, whereas the lysed bacterial suspension was weaker in its action. 

 The active substance was present extensively in old cultures and was 

 fairly stable. The material obtained by lysing the suspension of bacteria 

 by means of an antagonist was designated as "mycolysate." It did not 

 possess the toxicity of the nonlysed suspension but it preserved its anti- 

 genic properties {2>S^)' Gratia (354) also reported that actinomycetes 

 were able to attack living cells of bacteria, except E. coli and E. tyfhosa 

 which had to be first killed by heat before they could be dissolved. 



Welsch (100 1, 1002) made a detailed study of the lytic activity of 

 an actinomyces culture, presumably identical with that employed by 

 Gratia and later described as Actinomyces alhus. The culture was grown 

 in different media, the best results being obtained in very shallow layers 

 of ordinary bouillon. The active substance present in the filtrate was 

 designated as "actinomycetin." It was able to dissolve, at least partly, 

 all dead bacteria, whether killed by heat or by chemicals, gram-positive 

 or gram-negative, though gram-negative bacteria were, as a rule, more 

 susceptible. The growing culture of the antagonist brought about better 

 clarification (lysis) of the bacterial suspension than the filtrate. The 

 solubilizing properties of the active agent, its susceptibility to heat and 

 to ultraviolet rays, its size as measured by ultrafiltration, suggested its 

 protein nature. The kinetics of its action pointed to its being an enzyme. 

 It was precipitated by acetone, alcohol, and ammonium sulfate. Most 

 of the gram-negative bacteria were not attacked either by actinomycetin 



