Mycobiota and natural occurrence of aflatoxin, deoxynivalenol, nivalenol and zearalenone in rice freshly harvested in South Korea

The natural fungal mycobiota and contamination by aflatoxins (AFs), deoxynivalenol (DON), nivalenol (NIV), and zearalenone (ZEN) in rice from six locations (80 farms) in South Korea were surveyed during the harvest year 2010. Mycological analysis indicated that Fusarium was the predominant fungal genera, followed by Penicillium, Phoma, Myrothecium, and Cladosporium spp. Within the genus Fusarium, Fusarium graminearum was found most frequently. Polymerase chain reaction analysis targeting the AFs (aflR, omtB, ver-1 and omtA), DON/NIV (tri4, tri5, tri5–tri6, tri7 and tri13) and ZEN (pks4) biosynthetic genes showed that potential ZEN and NIV producers were the most prevalent. A similar trend was observed for the natural occurrence of all four mycotoxins. In both white and brown rice, ZEN was the main mycotoxin contaminant (range 0.4–95.4 μg/kg), followed by NIV; AFs and DON were not prevalent. The present study provides a detailed description of the fungi and natural occurrence of these four mycotoxins in rice at harvest, which may help in understanding the population dynamics and in developing effective control measures.