Production and Isolation of an Antibiotic from Monascus purpureus and its Relationship to Pigment Production

The cultural conditions and isolation methods for Monascidin A, an antibiotic from Monascus purpureus , are reported. A static liquid culture medium consisting of yeast extract (0.8%) and glucose (10%) is most suitable for antibiotic production in that most of the pigments accumulated within the mycelium while the antibiotic dissolved in the culture medium. Silica gel adsorption chromatography was used to separate major pigment components from the biologically active fractions, using an eluting solvent of benzene: methanol:chloroform (30:10:9, v/v/v). Further purification using silica gel TLC plates developed with benzene:methanol:chloroform (30:20:9, v/v/v) separated the active fractions into two components, a fluorescent yellow pigment and the pale yellow antibiotic. The dose response of Bacillus subtilis to the purified antibiotic was determined and the minimum effective dosage was about 1.5 μg per 6 mm paper assay disc.