Two Antagonistic Fungi, Aspergillus fumigatus and Aspergillus clavatus , and Their Antibiotic Substances

Abstract

It has been definitely established (Waksman, 1941; Waksman and Horning, 1942) that fungi capable of producing anti-bacterial substances are widely dis-tributed in nature and are not limited to any one or more taxonomic groups. Such fungi can be readily isolated from soils, manures, composts, and dust by the use of appropriate bacteria-enriched agar media. Out of some 160 antago-nistic fungi thus isolated, two organisms were selected for further study, because of their outstanding capacity to produce in culture media substances which inhibit in rather high dilutions the growth of various bacteria. These two or-ganisms were Aspergillus fumigatus Fresenius, of which 16 strains were isolated from different soils and composts, and Aspergillus clavatus Desmazieres, repre-sented by 3 isolations. The methods of testing the antibiotic action of the cul-ture filtrates of these organisms have been described in detail elsewhere (Waks-man and Homing, 1942). This paper deals specifically with the formation, concentration, and isolation of the antibiotic substances produced by these two fungi under different conditions of culture and nutrition. ASPERGILLUS FUMIGATUS