Purpose: Fusarium species and the contamination level of NIV and ZEN in rice from Korea were assessed.
Methods: Eighty rice samples were freshly harvested from 12 farm fields in Korea. After isolation of Fusarium species from the paddy rice, NIV and ZEN-producing strains were determined and characterized with multiplex PCR. We extracted DNA from 480 of Fusarium isolates, and amplified four genes in the NIV biosynthetic pathway (tri4, tri5-6 intergenic region, tri7 and tri13), and pks4 gene for ZEN biosynthesis. Rice was milled using a laboratory-scale test mill to produce four fractions: white rice, bran, brown rice and hulls. The four milling fractions were analyzed for NIV and ZEN with validated analytical method using high-performance liquid chromatography (HPLC) with UV absorbance and fluorescence detection.
Results: F. graminearum was the most frequent isolate in rice samples (92.5%), followed by F. proliferatum (33.8%), F. equiseti (29.4%), F. asiaticum (24.4%) and F. culmorum (8.1%). PCR assay results showed that NIV/ZEN genotype was the most predominant (75.4%) followed by ZEN genotype (10.2%) and NIV genotype (1.0%). Recoveries of NIV and ZEN in milling fractions with HPLC were 86.5 – 123.5% and 79.5 – 92.0%, respectively. The contamination levels in hulls, brown rice, bran and white rice were 180.4, 36.1, 108.5 and 12.4 µg/kg for NIV, and 537.8, 18.1, 93.9 and 0.6 µg/kg for ZEN, respectively. The contaminations of NIV and ZEN in rice have a good correlation with the frequency of toxigenic Fusarium isolates.
Significance: We confirmed that Fusarium species in Korean paddy rice was generally NIV and ZEN genotype and the contamination level of NIV and ZEN was reduced through milling process. This information is necessary of high priority in order to product the consumer’s health from the risk of exposure to these toxins.