84 BACTERIA AS ANTAGONISTS 



it liquefied gelatin and hemolyzed red blood corpuscles. When various 

 bacteria cultivated on a solid medium were suspended in physiological 

 salt solution and seeded with the antagonist, the latter developed abun- 

 dantly and the bacterial suspensions became clarified. The lysed solu- 

 tions of pneumococcus prepared by the use of the filtrate of B. subtilis 

 could be used for purposes of vaccination. In this connection, Nicolle 

 spoke of the work of Metchnikoff who had proved, in 1897, that or- 

 ganisms belonging to the B. subtilis group are capable of destroying 

 various bacterial toxins. Humfeld and Feustel (442) recently demon- 

 strated that an acid extract of B. subtilis cultures has a very high activity 

 against certain plant pathogens. This substance was designated as sub- 

 tilin. 



Rosenthal (768) isolated, from soil and from fecal matter, facultative 

 thermophilic antagonistic bacteria belonging to the B. mesentericus 

 group capable of dissolving both living and dead bacteria. The simul- 

 taneous growth of the antagonist with V . comma and other bacteria 

 brought about the clarification of the culture of the latter in about 5 or 

 6 days. These bacteriolytic organisms were designated as "lysobacteria." 

 It was recognized that the action of antagonists is different from that of 

 phage in several respects: (a) the filtrate of the antagonist is active 

 against other bacteria 5 (b) both living and dead cultures of bacteria are 

 dissolved J (c) antagonistic action is not so specific as that of phage j (d) 

 races of E. colt resistant to phage are dissolved by the filtrate of the an- 

 tagonist. The active substance was believed to be of the nature of an 

 enzyme. Friedlander's bacillus was not acted upon, possibly because of 

 the formation of a pellicle by the bacillus. The active substance was 

 formed in 4 to 5 days but increased in activity after 2 to 3 weeks. It was 

 essential that a surface pellicle of the organism be maintained. Sub- 

 merged growth was less favorable. Fresh filtrates had the greatest ac- 

 tivity, the property being lost after storage for 3 months. The substance 

 was thermolabile, activity being destroyed at 70° C. The filtrate of an 

 organism dissolved by the action of the antagonist proved to be as ac- 

 tive as the filtrate of the culture of the antagonist. It acted injuriously 

 upon intestinal bacteria not only in vitro but also in vivo. 



Much and associates (620) isolated several strains of B. mycoides 

 that possessed strong antagonistic properties. The active strains were 



