Quantitative PCR (qPCR) for estimating the presence of Fusarium and its mycotoxins in barley grains.

Members within the Fusarium sambucinum species complex (FSAMSC) are able to produce mycotoxins, such as deoxynivalenol (DON), nivalenol (NIV), zearalenone (ZEN) and enniatins (ENNs) in food products. Consequently, alternative methods for assessing the levels of these mycotoxins are relevant for quick decision-making. In this context, qPCR based on key mycotoxin biosynthetic genes could aid in determining the toxigenic fungal biomass, and could therefore infer mycotoxin content. The aim of this study was to verify the use of qPCR as a technique for estimating DON, NIV, ENNs and ZEN, as well as Fusarium graminearum sensu lato (s.l.) and F. poae in barley grains. For this purpose, 53 barley samples were selected for mycobiota, mycotoxin and qPCR analyses. ENNs were the most frequent mycotoxins, followed by DON, ZEN and NIV. 83% of the samples were contaminated by F. graminearum s.l. and 51% by F. poae. Pearson correlation analysis showed significant correlations for TRI12/15-ADON with DON, ESYN1 with ENNs, TRI12/15-ADON and ZEB1 with F. graminearum s.l., as well as ESYN1 and TRI12/NIV with F. poae. Based on the results, qPCR could be useful for the assessment of Fusarium presence, and therefore, provide an estimation of its mycotoxins' levels from the same sample.

Characterization of the Fusarium sambucinum species complex and detection of multiple mycotoxins in Brazilian barley samples.

This study investigated the fungal diversity in Brazilian barley samples, focusing on the Fusarium sambucinum species complex and the presence of multiple mycotoxins: aflatoxins B1, B2, G1, G2 beauvericin (BEA), enniatins (ENNs) A, A1, B, and B1, deoxynivalenol (DON), fumonisins (FB) B1 and B2, HT-2 and T-2 toxins, nivalenol (NIV) and ochratoxin A (OTA) from two different regions, São Paulo (SP) and Rio Grande do Sul (RS). The majority of the isolates belonged to the Fusarium sambucinum species complex (FSAMSC), with F. graminearum s.s. characterized as the major contaminant. F. meridionale and F. poae were the second most frequent fungi isolated from SP and RS, respectively. All of the F. graminearum s.s. isolates demonstrated 15-ADON genotype, whereas F. poae and F. meridionale were all NIV. The majority of the F. cortaderiae isolates were NIV, with only one 3-ADON genotype. Mycotoxin analysis revealed that none of the samples were contaminated by aflatoxins, OTA, FB2 and type A trichothecenes, however, all of the samples were contaminated with at least one Fusarium toxin. Contamination by DON, ZEA, ENNB and ENNB1 levels were significantly higher in RS. Co-contamination of BEA, DON, ENNs, NIV and ZEA in 18.5% and 24.2% of the analyzed samples was observed, from SP and RS respectively. More than 20% of the samples from RS presented DON and ZEA levels above the regulations established by Europe and Brazil. The results provide further information on the FSAMSC from South America and detected multiple Fusarium toxins in barley samples. This highlights the importance for further studies on the possible interactions of these mycotoxins in order to determine potential risks to animal health.

Fusarium Mycotoxins in Two Hulless Oat and Barley Cultivars Used for Food Purposes.

Hulless oats and hulless barley are highly valued for their excellent nutritional attributes and are increasingly being promoted in human nutrition. However, special attention should be paid to the risk of their contamination by Fusarium mycotoxins, as the rate of mycotoxin reduction during processing could be much lower than that for hulled cereals. In the present study, mycotoxin contamination of two cultivars, each of hulless oats and barley suitable for food purposes were studied in a 3-year field trial established in two contrasting environments. The contents of the mycotoxins regulated by law (deoxynivalenol and zearalenone) were low, and the present legal limits for their maximum content in unprocessed cereals were far from being exceeded. The mycotoxins most frequently occurring in hulless barley were enniatins (enniatin B, enniatin B1 and enniatin A1), beauvericin and nivalenol; hulless oats most frequently contained the HT-2 and T-2 toxins, beauvericin and enniatin B. The contents of enniatins and nivalenol were higher in barley than in oats. Close, positive relationships between the contents of the individual enniatins and between enniatins, beauvericin and nivalenol were observed, which implies that co-exposure could enhance the toxic potential of these mycotoxins through synergistic effects. The results highlight the need to pay more attention to the occurrence of enniatins, beauvericine and nivalenol in hulless oats and barley used for food purposes.