88 BACTERIA AS ANTAGONISTS 



produced on artificial media an active substance that suppressed the 

 growth of Helminthosforium sativum. It increased sporulation of the 

 fungus, inhibited or retarded spore germination, caused abnormal 

 hyphal development, and induced mutations in certain strains of the 

 fungus. The substance was thermostable and diffusible. It passed 

 through a Berkfeld filter, was absorbed by infusorial earth, withstood 

 freezing and desiccation, and did not deteriorate readily. It was de- 

 stroyed by alkalies but not by acids. It was inactivated or destroyed, 

 however, by certain fungi and bacteria. 



TABLE 13. BIOCHEMICAL CHARACTERISTICS OF ACTIVE AND INACTIVE 

 STRAINS OF SPORE-FORMING SOIL BACTERIA 



NONSPORE-FORMING BACTERIA: PS. AERUGINOSA, 

 PS. FLUORESCENS, AND S. MARCESCENS 



Among the bacteria, those belonging to the fluorescent, green- 

 pigment and red-pigment producing groups have probably received 

 the greatest attention as antagonists. Bouchard ( 8 1 ) first reported, in 

 1888, that Ps. aeruginosa was antagonistic to B. anthracis; the presence 



