The isolation of a fungal metabolite which exhibits antimicrobial synergy with sterigmatocystin

Abstract

A metabolite, which acted synergistically with sterigmatocystin to inhibit the growth of several Gram positive bacteria, has been isolated from several strains of Aspergillus nidulans. Preliminary characterization of this metabolite indicated that it was a high‐molecular‐weight glycoprotein. Dihydrosterigmatocystin, aflatoxin B, and aflatoxin Gt all failed to exhibit antimicrobial synergy with the glycoprotein. Thus, the synergy with the glycoprotein was specific for sterigmatocystin and the presence of the unsaturated bifuran moiety was shown to be essential to the antimicrobial action of the synergy.

The effect of the synergy between sterigmatocystin and a fungal metabolite on Bacillus subtilis

“…We therefore believe that the site of action of component I is the bacterial cell and not STG. In the preceding paper (Perry et al 1982) we reported that component I was a glycoprotein with a molecular weight in excess of 300000. Such a molecule would certainly not readily be able to enter the bacterial cell, suggesting that the site of action is extracellular.…”

“…Agents which were known to alter the permeability of bacterial cells (Sebek 1967;Hamilton 1971;Plotz & Davis 1962;Storm 1974) were tested for their ability to exhibit antimicrobial synergy with STG. Thus the MIC values of penicillin G, polymixin B, bacitracin and Triton Xi00 against B. subtilis were established both in the presence (5pglml) and absence of STG, using the agar plate diffusion assay described previously (Perry et al 1982).…”