ANTIBACTERIAL EFFECTS 143 



of M. tuberculosis. As pointed out previously, Vaudremer recorded in 

 1 913 (934) that the fungus produces a thermostable substance which is 

 responsible for the antituberculosis effect. Zorzoli (1051) reported in 

 1940 that A. fumigatus produces a thermostable substance (100° C. 

 for I hour) which interferes with the growth of M. tuberculosis. Ashes- 

 hov and Strelitz (27) observed a marked action oi A. fumigatus prepa- 

 rations upon the B.C.G. but not upon the avian strain of M. tuberculo- 

 sis; the bacteriostatic activity was greater against M. tuberculosis 

 B.C.G. than against staphylococci, although the bactericidal activity was 

 lower. Culture filtrates and extracts of various unidentified fungi were 

 found capable of inhibiting the growth of the organism (647). One 

 such extract was designated as mycocidinj its effect upon the human 

 tubercle bacillus was both bacteriostatic and bactericidal (328). Jen- 

 nings (464) reported that helvolic acid (fumigacin), one of the anti- 

 biotics produced by A. fumigatus y in concentrations of 1:10,000 in- 

 hibited completely and in i : 100,000 only partly, the growth of the 

 tuberculosis organism isolated from sputum. 



A . ustus produces in ordinary Czapek-Dox medium with 4 per cent 

 glucose and o.i per cent yeast extract, after 14 to 19 days' incubation, a 

 substance that inhibits the growth of M. tuberculosis and M. ranae 

 (539). This antibiotic can be extracted from the medium with ether and 

 other organic solvents. The ether residue is dissolved in phosphate 

 buffer of fH. 1 1 .0. On acidification of the alkaline solvent, a yellow 

 flocculent precipitate is obtained. This substance inhibited the growth 

 of M. ranae in a dilution of 1:150,000, and the acid precipitate in 

 1 : 300,000 dilution. By means of a "countercurrent distribution" the 

 active agent was separated into two crystalline and one partially crys- 

 talline preparations (438). 



The mycelium of A. ustus was found (188) to contain a group of 

 antibiotics, one of which was designated as ustin. This substance was 

 active against gram-positive, including acid-fast, bacteria (1:500,000). 

 It is inhibited by serum albumins and by lipids. 



Aspergillus clavatus Group 



This comprises a number of strains that produce highly active anti- 

 biotic substances. By treating the culture filtrate with charcoal and 



