Natural and in vitro coproduction of cyclopiazonic acid and aflatoxins.

摘要

A total of 80 samples of animal feeds of different origins, collected from factories in Portugal, were screened for the natural co-occurrence of cyclopiazonic acid (CPA) and aflatoxins. 45 strains of Aspergillus flavus were collected from those samples and studied for their ability to produce these mycotoxins in vitro. CPA was detected by thin-layer chromatography using Erhlich's reagent for confirmation; aflatoxins were determined by HPLC with postcolumn iodination. Only 5 of the 80 samples (6.2%)were naturally contaminated with CPA (0.16 mg/kg) and 36 (45.0%) with aflatoxin B1 (AFB1) (0.001-0.016 mg/kg). An in vitro study of the 45 A. flavus strains was performed in cracked corn [maize] at 25deg C (water activity, aw=0.96), incubated for 21 days to CPA production. For in vitro production of aflatoxins, the same substrate was incubated at 28deg C for 14 days. 19 (42.2%) strains produced CPA (0.5-1.45 mg/kg CPA) and 23 (51.1%) produced AFB1 (0.001-0.844 mg/kg). Only 10 isolates (22.2%) produced both CPA and AFB1 (0.05-0.10 mg/kg and 0.001-0.230 mg/kg, respectively). 13 strains did not produce either CPA nor AFB1.