ANTIBACTERIAL EFFECTS 131 



Atkinson (26) tested 68 cultures of Penicillium and found that 18 

 possessed antibacterial properties. These cultures were divided into 

 two groups : first, those largely active against gram-positive bacteria and 

 producing substances like penicillin and citrininj second, those active 

 also against gram-negative bacteria and producing substances of the 

 penicillic acid and penicidin types. 



Asfergillus jlavus-oryzae Group 



The A . oryzae members of this group possess only limited antagonis- 

 tic properties. Many of the A . flavus strains, however, have apparently 

 the property of producing at least two antibacterial substances when 

 grown on suitable media and under suitable conditions. 



White and Hill (978) isolated from cultures of a strain of this or- 

 ganism grown on tryptone media a crystalline substance, aspergillic 

 acid, that showed antibacterial activity against certain gram-negative as 

 well as gram-positive bacteria. The substance was produced when the 

 organism was grown on organic media, but not on synthetic. It was 

 soluble in ether, alcohol, acetone, or acetic acid, but not in petroleum 

 ether J it was soluble in dilute acid or alkaline aqueous solutions, and 

 was precipitated by phosphotungstic acid. Aspergillic acid proved to 

 have relatively high toxicity, and showed no protective action against 

 hemolytic streptococci or pneumococci infections in mice. 



Glister, in England, isolated a strain of A. flavus (330) that also 

 produced an antibacterial agent with a wide range of activity, both 

 gram-positive and gram-negative bacteria being inhibited by the culture 

 filtrate. An extract was obtained that inhibited the growth of these bac- 

 teria in a dilution of approximately i : 200,000. 



Jones, Rake, and Hamre (461 ) demonstrated that A . flavus of White 

 produces frequent variants 5 two strains were isolated and were found 

 to give consistently far higher yields of the antibiotic substance, asper- 

 gillic acid, than those reported by White. The substance was found to 

 have wide activity, being very active against gram-positive cocci and less 

 active against the anaerobes of gas gangrene and the gram-negative ba- 

 cilli. No significant differences were found in the spectrum of activity as 

 shown by filtrates or by solutions of purified aspergillic acid. 



