Penicillium verrucosum in wheat and barley indicates presence of ochratoxin A

Abstract

AIMS: The aims of this study were to isolate and identify ochratoxin A (OTA) producing fungi in cereals containing OTA and to determine the best selective and indicative medium for recovery of OTA producing fungi. METHODS AND RESULTS: Seventy-six wheat, barley and rye samples from Europe containing OTA and 17 samples without OTA were investigated using three different media, dichloran yeast sucrose agar (DYSG), dichloran rose bengal yeast extract sucrose agar (DRYES) and dichloran 18% glycerol agar (DG18). Hundred kernels were plated on each medium and the kind and number of fungal OTA producers were recorded as percentage of infestation. Penicillium verrucosum was the sole OTA producer found in cereals. The average percentage of infestation of P. verrucosum counts was recorded as 28.3% on DYSG, 10.3% on DRYES and 9.9% on DG18 on the OTA containing samples and 0.8% on DYSG, 0.4% on DRYES and 0.6% on DG18 for the samples without OTA. CONCLUSIONS: Penicillium verrucosum was the sole OTA producer in European cereals. Determination of P. verrucosum infestation and infection was best detected on DYSG after 7 days at 20 degrees C. The percentage of infestation of P. verrucosum found on DYSG and OTA content in cereals were correlated. More than 7% infestation of P. verrucosum indicated OTA contamination. SIGNIFICANCE AND IMPACT OF THE STUDY: The developed method could be used as a cereal quality control.