CHAPTER 5 



BACTERIA AS ANTAGONISTS 



Following the early work of Pasteur (674) on the antagonistic ef- 

 fects of bacteria against the anthrax organism, considerable attention 

 has been centered upon bacteria as agents possessing antibacterial prop- 

 erties. A systematic study of this phenomenon was first made by Babes 

 in 1885 (150), followed by Garre in 1887 and Freudenreich in 1888. 

 Freudenreich (299) demonstrated that when certain bacteria were 

 grown in a liquid medium, the filtrate obtained by passing the culture 

 through a porcelain candle supported the growth of the typhoid or- 

 ganism not at all or only very feebly. Garre (311) observed that Ps. 

 -putida inhibited the growth of S. aureus, E. tyfhosa, and Bacillus muco- 

 sus-cafsulatus but not of B. anthrac'ts and other bacteria. It was soon 

 reported (524), however, that B. anthracis was also killed by the 

 Pseudomonas antagonist, whereas the growth of 5. aureus and V . 

 comma was only retarded j no effect at all was exerted upon E. tyfhosa 

 and E. coli. In consequence, the antagonist was claimed to be active 

 against B. anthracis but not against other bacteria. Olitsky {6ss) con- 

 cluded that Ps. fuorescens inhibited the growth not only of E. tyfhosa 

 but also of B. anthracis, V . comma, S. marcescens, and S. aureus. These 

 and other apparently contradictory results were undoubtedly due to 

 diflFerences in the specific nature of the strains of the organisms used by 

 the various investigators and to different methods of cultivation. 



The presence of Ps. fiuorescens in sewage was found (517) to reduce 

 greatly the period of survival of the typhoid organism. The latter did 

 not develop even in gelatin upon which Ps. fluorescens had previously 

 grown (326, 430, 431, 432), and it could not be detected in sterile sew- 

 age in which the antagonist was present for seven days. According to 

 Frost (302), E. tyfhosa can be antagonized by a number of different 

 soil bacteria, of which Ps. fluorescens exhibits the strongest effect. He 

 observed that although P. vulgaris acted more rapidly, the active sub- 

 stance did not diffuse to so great a distance in the medium, thus point- 



