An easy screening method for fungi producing ochratoxin A in pure culture

A simple screening method has been developed for detecting ochratoxin production by fungi, based on high-performance liquid chromatographic determinations on extracts obtained from agar plugs cut from pure Petri dish cultures. Two culture media, Yeast Extract Sucrose agar and Czapek Yeast Extract agar, and three extraction solvents (methanol, methylene chloride/formic acid, and methanol/formic acid) were compared. All of the isolates tested produced ochratoxin A in one or both culture media after 7 or 14 days of incubation. Based on the results obtained, the use of both culture media is recommended. As extraction solvent, either methanol or methanol-formic acid could be used. This method also provides quantitative information on the level of ochratoxin produced by the cultures. The simplicity of the method makes it very useful when many fungal isolates need to be screened.