Antibiotic produced by Fusarium equiseti NRRL 5537.

Fusarium equiseti NRRL 5537 grown on an autoclaved white corn grit medium for 3 to 4 weeks at room temperature produced a substance in excess of 5 g/kg of substrate that inhibited some gram-positive bacteria including mycobacteria. Most Bacillus subtilis, Mycobacterium phlei, and Staphylococcus aureus strains were inhibited when 1 mug of the antibiotic per ml was incorporated into the culture medium. Except for Neisseria perflava, gram-negative bacteria, yeasts, and molds were not inhibited by 128 mug/ml. The antibiotic was recovered as a white powder, had a melting point of 65 to 66 C, and had an intraperitoneal mean lethal dose in white mice of 63 mg/kg of body weight. In thin-layer chromatographic analysis the compound appeared as a single spot in two different solvent systems. Mass spectrometry determined that the molecular weight of the antibiotic was 373 with a molecular formula of C(22)H(31)NO(4). Chemical microanalysis was in accord with the formula.