Purification of antibiotics from Physarum gyrosum by high pressure liquid chromatography

A family of five antibiotic substances was isolated from the slime mold Physarum gyrosum by high pressure liquid chromatography (HPLC). For this purpose, mold was cultured for two weeks in a liquid medium. Soluble products were harvested by rotary evaporation of medium and extraction with 1-butanol. Paper chromatography in ethyl acetate:pyridine:water (2:2:1 v/v) was used for preliminary fractionation. Active components were separated by HPLC with a reverse-phase column packed with Bondapack C18/Porasil B (Waters Associates) and were eluted with a linear gradient of methanol:water increasing from 70 to 100% methanol over 90 minutes. Purification was completed by rechromatographing individual fractions. Purity of the active components was verified by HPLC and thin layer chromatography. Activity assays against Bacillus cereus showed these materials to be bacteriostatic rather than bacteriocidal.