Studies on Antibacterial Products Formed by Molds: I. Aspergillic Acid, a Product of a Strain of Aspergillus Flavus.

In 1940 one of us (White) reported that a strain of Aspergillusflavus, grown on certain liquid media, yielded filtrates that showed antibacterial activity against certain gram-negative as well as gram-positive bacteria. This was the second reported case of such behavior by a mold, the first being that of Fleming (1929), who found that a strain of Penicillium notatum formed a product that was inhibitory, but not markedly lethal, to certain gram-positive bacteria. Fleming's mold has since been the subject of much further investigation, culminating in the preparation of a highly potent product by McKee and Rake (1942) and in the recent report by Meyer et al. (1942) which describes the isolation of an extremely potent, crystalline inhibitory substance, to which the name "penicillin" is given. The present paper presents details of the isolation of an active crystalline substance from liquid cultures of our strain of Aspergillus flavus. Glister (1941) has also reported obtaining a potent antibacterial concentrate from an Aspergillus, but apparently not in pure crystalline form. Whether the active part is the same as our product is not apparent at this time. We propose to call our substance "aspergillic acid."