Abstract
An antibiotic substance has been purely isolated from the culture filtrates of Gloeosporium olivarum Alm. which was grown for 12 days in the presence of 0.03% 2-methyl-4 chlorophenoxyacetic acid (MCP). The yield was 0.181mg/ml of the original filtrate. This compound of white needle-shaped crystals, m. p. 55°C, is thermostable, nearly insoluble in cold water, but soluble in hot water and many organic solvents. It contains C, H, O, Cl and the hydroxyl group characteristic to a primary or secondary alcohol, but does not contain S, P and N·The one-dimensional paper-partition chromatogram of the antibiotic developed by ascending technique with acetone-methanol-water mixtures (30:5:65v/v) showed a single inhibiting zone at Rf 0.73. When the antibiotic was incorporated into agar media at the dilution of 1:5, 000, the growth of G. olivarum and Cochliobolus miyabeanus was almost completely inhibited, the dilution end-point being about at I:40, 000 and 1:30, 000 against the former fungus and Corticium centrifugum respectively. Conidial germination of G. olivarum was entirely inhibited at 1:3, 000. In the other experiment by paper disk method, it also exerted a toxicity against other 5 species of phytopathogenic fungi and 5 species of bacteria. The inhibitory activity of MCP in vitro on G. olivarum is considered to be attributable to this antibiotic produced by addition of MCP rather than to its direct effect on the pathogen.
