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 28AE3% on DYSG, 10AE3% on DRYES and 9AE9% on DG18 on the OTA containing samples and 0AE8% on DYSG, 0AE4% on DRYES and 0AE6% 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°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.

Penicillium verrucosum occurrence and Ochratoxin A contents in organically cultivated grain with special reference to ancient wheat types and drying practice

“…% (Figure 2). This is in accordance with Lund & Frisvad [15], who suggested that microbial interactions in the grain and microbial interactions with their environment are responsible for this lack of correlation. Some kernels and spikelets were most likely not infected by the fungus but merely surface contaminated.…”

“…All plates were incubated for 7 days at 25°C. The kernels were not surface-disinfected prior to plating, because P. verrucosum is sensitive to this procedure [15]. Based on its terra-cotta coloured reverse, the number of kernels colonized by P. verrucosum were enumerated.…”

Ochratoxin A and Brewing Technology: A Review

“…Ambient drying systems in damp autumns require longer drying and this can result in the layers of the drying grain reabsorbing moisture and allowing the mycotoxigenic mould to become established. It is also a very competitive species and able to dominate under conducive environmental conditions in the stored grain 73 . Some studies have suggested that the level of contamination by P. verrucosum is a good indication of potential contamination with ochratoxin A 70,72,91 .…”

Inhibition of ochratoxin A production of Aspergillus carbonarius by yeast species

“…Ochratoxin A is produced by several fungal species in the Penicillium and Aspergillus genera, primarily Penicillium verrucosum, Aspergillus ochraceus and Aspergilli of the section Nigri, especially A. carbonarius (EFSA 2006). While P. verrucosum is the main OTA producer in cereals (Lund & Frisvad 2003), Aspergillus species such as A. ochraceus and A. carbonarius are typically associated with coffee, species and grapes (JECFA 2001). Among these species, A. carbonarius is considered to be a major source of OTA in grapes and wine (Serra et al 2003;Sage et al 2004).…”