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 distributed 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 antagonistic 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 organisms were Aspergillus fumigatus Fresenius, of which 16 strains were isolated from different soils and composts, and Aspergillus clavatus Desmazieres, represented by 3 isolations. The methods of testing the antibiotic action of the culture filtrates of these organisms have been described in detail elsewhere (Waksman 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 When grown in simple synthetic media A. fumigatus produces an antibiotic substance, which has been designated as "fumigacin" (Waksman, Horning and Spencer, 1942). The medium used most extensively for this purpose was that of Czapek-Dox or a glucose-nitrate solution, which consists of 40 g. glucose, 3 g. NaNO3, 1 g. KH2PO4, 0.5 g. KCl, 0.5 g. MgSO4 7H20, 0.01 g. FeSO4.7H20, and 1000 ml. tap water.-The antibiotic substance was found to be produced in this medium during the early stage of growth of the organism: its presence could be demonstrated even within 3 days incubation at 28°C; it reached a maximum in 7-8 days, and then gradually disappeared on further incubation. The reduction in activity is due either to the destruction of the active substance or to its transformation into an inactive or at least a less active type of compound. In view of the recent announcement made by Oxford and Raistrick (1942) that fumigatin, a maroon-colored pigment produced by A. fumigatus, also has antibacterial properties, it was desirable to establish first the possible relation between the nature and formation of fumigatin and fumigacin, as well as their chemical and biological differences. This can be done by comparing the results on fumigacin obtained in this laboratory, with those on fumigatin reported from

Occurrence and significance of mycotoxins in forage crops and silage: a review

“…Some isolates of A fumigatus produce a steroid like antibiotic, helvolic acid (Wakeman et al 1943). Aspergillus fumigatus has also been reported as being able to synthesise dicoumarol and 4-hydroxy coumarin in cultures containing o-coumaric acid (Bye et al 1968 ;Bye and King 1970).…”

The Nature of the Antibiotic Substances Produced by Aspergillus fumigatus

“…This was confirmed by the observation that the two fractions of gliotoxin obtained from sulfate-containing media contained sulfur whereas the two others did not. The previous findings on the toxicity of fumigacin, as reported by Waksman, Horning and Spencer (1943) and by Robinson (1943) must now be considered in a new light, namely in terms of purified fumigacin, freed from the gliotoxin fraction. Whereas earlier reports indicated that 4 mg of fumigacin injected into 20 gm weight mice by the intraperitoneal method showed evidence of toxicity, the purified fumigacin was tolerated by mice even in concentrations of 16 mg/20 gm.…”

“…The method of extraction of fumigacin from the medium was found to have a considerable influence upon the purity of the fumigacin obtained and upon the amount of gliotoxin accompanying it. When the medium is treated by the WHS method (Waksman, Horning, and Spencer, 1943), namely, adsorption on norit, followed by extraction with chloroform, or ether followed by chloroform, only E, limited amount of gliotoxin is found admixed with the fumigacin. However, where the two substances are extracted directly from the medium, using the MWH method (Menzel, Wintersteiner, and Hoogerheide, 1944) a much larger yield of gliotoxin is obtained, the yield of fumigacin remaining, however, practically the same.…”

“…Gliotoxin contains 8.59 per cent nitrogen and 19.65 per cent sulfur. These investigators demonstrated that the crystalline preparation of fumigacin obtained by Waksman, Horning, and Spencer (1943) contains about 20 per cent of a gliotoxin fraction. This accom-…”

Wild rice as fermentation substrate for mycotoxin production

“…A sample of processed wild rice that had become damp and moldy through accident was examined by plating out on Czapek solution agar and identifying the isolates. Since the predominating species was found to be A. clavatus, a known Pat producer (16), a composite sample of the moldy rice was extracted and assayed for this toxin by the methods of Pohland and Allen (12). In addition, a typical isolate from the moldy wild rice was tested, along with a known Pat-producing strain, A. clavatus NRRL 1980, as control, for ability to produce Pat.…”