142 



FUNGI AS ANTAGONISTS 



Aspergillus jufnigatus Group 



Four antibacterial substances were isolated from strains of A . fumi- 

 gatus: the two pigments, spinulosin and fumigatin (702), which are 

 not selective in their action against bacteria, the colorless fumigacin 

 that is active largely against gram-positive organisms (957), and glio- 

 toxin (339, 631). Helvolic acid, isolated from a strain of A. jumigatus 

 (126, 161), was found (631, 955) to be identical with purified fumi- 

 gacin. 



Fumigacin is active against S. aureus in dilutions of i : 200,000 to 

 1 : 750,000 and is very stable. The pigment fumigatin, however, was 

 said to deteriorate on standing, inhibition of S. aureus being reduced 

 from 1 150,000 to 1 : 25,000 in 7 days. Fumigacin has a certain degree 

 of resistance to high temperatures. Boiling in aqueous solution for 5 to 

 10 minutes reduced but did not destroy completely its activity. Heat- 

 ing at 80° C. for 15 minutes reduced the activity only slightly. When 

 fumigacin was dissolved in alcohol and precipitated by addition of nine 

 volumes of water, the alcohol-water solution was found to contain 0.25 

 mg. per ml. A comparison of the antibacterial activity of fumigacin with 

 that of the other substances produced by A. jumigatus is given in 

 Table 27. 



A number of fungi, largely Aspergilli and usually members of the 

 A . jumigatus group, have been found to be able to inhibit the growth 



TABLE 27. CHEMICAL PROPERTIES AND BACTERIOSTATIC ACTIVITY OF FOUR 

 ANTIBIOTIC SUBSTANCES PRODUCED BY ASPERGILLUS FUMIGATUS 



MELTING 

 CRYSTALLI- POINT 



SUBSTANCE ZATION ° C. FORMULA 



BACTERIOSTATIC ACTIVITY 

 IN DILUTION UNITS 



B. sub- 

 E. coli S. aureus tills 



Spinulosin Purplish-bronze 



plates 201 CgHgOg 



Fumigatin Maroon-colored 



needles 116 CgHgOg 



Fumigacin Very fine white 



needles 215-220 C32H44O8 



Gliotoxin Elongated 



plates 195 C13H14O4N2S2 6,000 1,500,000 750,000 



1,200 200,000 40,000 

 1,200 2,000,000 100,000 



