A convenient method for assessing mycotoxin production in cultures of aspergilli and penicillia

Production of aflatoxins, sterigmatocystin, citrinin, and ochratoxin A by Aspergillus and Penicillium species on agar in 50-ml flasks after 21 days was detected and confirmed by thin-layer chromatography. Toxins were extracted with 2.5 ml of acidified methylene chloride for 20 to 60 min. Mycotoxin concentrations were estimated by liquid chromatography. Addition of formic acid to the methylene chloride extraction solvent effected an increase in recovery of ochratoxin A from Czapek-yeast (CY) agar from 20% to 91%. Recoveries of added mycotoxins were generally higher from CY agar than from yeast extract-sucrose (YES) agar and ranged from 11% (citrinin from YES agar) to 91% (ochratoxin A from CY agar). The method described is convenient, rapid, and reproducible, since it samples the entire culture surface. Human exposure to volatile solvents is also minimized.