ANTAGONISTIC PROPERTIES 107 



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 other gram-negative bacteria, such as Ps. aeruginosa; however, 

 it was inactive toward 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 (349). Gratia (347) 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 (972, 973) made a detailed study of the lytic activity of an 

 actinomyces culture, presumably identical with the one 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 

 (971). It was precipitated by acetone, alcohol, and ammonium sulfate. 

 Most of the gram-negative bacteria were not attacked either by actino- 

 mycetin or by the living culture of the antagonist. Only a few of the 

 gram-positive bacteria, including certain pneumococci and streptococci, 

 could be dissolved by sterile actinomycetin, A definite parallelism in 

 the activity of the preparation against dead bacteria and of the living 



