244 NATURE OF ANTIBIOTIC ACTION 



Fumigacin is active only upon gram-positive bacteria and has a rather 

 limited bactericidal effect. Its action upon tubercle bacteria has recently 

 attracted considerable attention (27). Partially purified preparations 

 inhibited multiplication of the human strain of M. tuberculosis in dilu- 

 tions as high as i : 1,400,000. Killing effect was exerted by a dilution of 

 1:500,0005 this was measured by incubation of a heavy suspension of 

 the bacteria with different dilutions of the substance, incubating 24 

 hours, and measuring for viability. The avian type of M. tuberculosis 

 was not affected. 



A s-per gillie Acid 



Aspergillic acid is active against various bacteria, including the hu- 

 man strains of M. tuberculosis. It was suggested that its mode of action 

 is due to interference with the utilization of iron by this organism 

 (348). The favorable effect of cobaltous ion on the tuberculostatic ac- 

 tion of this antibiotic has been established (349). 



Gliotoxin 



Gliotoxin is active against both gram-positive and gram-negative bac- 

 teria (Table 39). The substance is rather toxic to animals, the minimum 

 lethal dose being 45 to 6s mg. per kilogram body weight j hematuria 

 is caused by even lower concentrations (474). 



TABLE 39. BACTERIOSTATIC ACTION OF GLIOTOXIN 



From Johnson, Bruce, and Dutcher (475). 

 Note. Units of activity by dilution method. 



