90 BACTERIA AS ANTAGONISTS 



antagonist. A lytic effect was also exerted upon staphylococci (824) and 

 gram-negative bacteria (504, 505). The substance was precipitated by 

 10 per cent tungstic acid and lead acetate and was thermostable. 



Much and Sartorius (664) came to the conclusion that B. mycoides 

 Flugge comprises two groups of organisms. One produces branching 

 colonies on agar and forms no pellicle in meat broth, the flaky growth 

 dropping to the bottom and the medium remaining more or less clear. 

 The second group forms flat surface growth similar to that of B. mes- 

 enterkus on agar and a pellicle on the surface of liquid media. Many 

 of the pellicle-forming strains have the capacity, in varying degrees, of 

 dissolving various cultures of bacteria. This is not due to their proteo- 

 lytic activity, since members of the first group may be more actively 

 proteolytic. The culture filtrate of the antagonist dissolves the bacteria 

 but does not destroy their antigenic properties. The lytic substance, 

 designated as Much-lysin, was said to have a double effect: one, bound 

 to the living cells of the organism, had nothing to do with phage, and 

 the other, found in the bacteria-free filtrate, had an apparent similarity 

 to phage but was distinct from it. 



The idea that in the case of bacterial antagonists one is dealing with 

 specific strains rather than with distinct species was further emphasized 

 by Franke and Ismet (292). Various strains of B. mycoides, desig- 

 nated as cytolitkusy were shown to be able to lyse many pathogenic and 

 nonpathogenic bacteria but not their own cells j the same action was 

 exerted by the culture filtrate (Table 11). The lytic action of strains of 

 B. subtilis upon different bacteria, including M. tuberculosis (927), 

 pneumococci, typhoid, diphtheria, and other organisms, has also been 

 definitely established. 



Pringsheim (738) isolated a strain of B. mesentericus-vulgatus that 

 had a decided inhibiting effect upon a variety of bacteria, particularly 

 Corynebacterium difhtheriae. On agar plates the antagonist produced 

 a circular zone of inhibition, just beyond which was a ring of larger 

 colonies, indicating a stimulating effect. It was suggested that the an- 

 tagonist produced a toxin that was stimulating in small doses and in- 

 jurious in larger concentrations. The active substance was thermolabile 

 and nonfilterable. The antagonistic properties appeared to be inherent 

 in the particular strain of an organism and were not increased by serial 



