Deoxynivalenol and other selected Fusarium toxins in Swedish oats — Occurrence and correlation to specific Fusarium species

• Most oat samples were contaminated with more than four toxigenic Fusarium species.
• DON, NIV, beauvericin and enniatins were present in < 90% of the samples.
• Higher levels of DON and F. graminearum in 2011.
• F. graminearum, DON and ZEA levels were higher in the West part of Sweden.

Fusarium moulds frequently contaminate oats and other cereals world-wide, including those grown in Northern Europe. To investigate the presence of toxigenic Fusarium species and their toxins in oats, samples were taken during 2010 and 2011 in three geographical regions of Sweden (east, west, south). The samples were analysed by real-time PCR for the specific infection level of seven Fusarium species associated with oats and other cereals (Fusarium poae, Fusarium graminearum, Fusarium langsethiae, Fusarium culmorum, Fusarium tricinctum, Fusarium sporotrichioides and Fusarium avenaceum) and with a multi-mycotoxin method based on liquid chromatography/electrospray ionisation-tandem mass spectrometry (HPLC/ESI-MS/MS) for the detection of many fungal metabolites, including deoxynivalenol (DON), zearalenone (ZEA), nivalenol (NIV), T-2 toxin, HT-2 toxins, moniliformin (MON), beauvericin (BEA) and enniatins (ENNs).Most samples contained at least four of the seven Fusarium species analysed and F. poae, F. langsethiae and F. avenaceum were present in approximately 90–100% of all samples. The most common toxins detected were DON, NIV, BEA and ENNs, which were present in more than 90% of samples. Most Fusarium species and their toxins occurred in higher concentrations in 2010 than in 2011, with the exception of DON and its main producer F. graminearum. Significant regional differences were detected for some moulds and mycotoxins, with higher levels of F. graminearum, DON and ZEA in western Sweden than in the east (P < 0.05) and higher levels of F. tricinctum and MON in the south (P < 0.05).Correlation analysis showed significant correlations between many Fusarium species and toxin levels. For example, F. tricinctum was significantly correlated to F. avenaceum (r = 0.72, P < 0.001), DON to ZEA (r = 0.52, P < 0.001), DON to F. graminearum (r = 0.77, P < 0.001) and the sum of T-2 and HT-2 to F. langsethiae (r = 0.77, P < 0.001).The multi-toxin approach employed allowed simultaneous detection of many Fusarium mycotoxins in each sample. In combination with real-time PCR analysis of seven toxigenic Fusarium spp., the results gave an overall picture of the presence of Fusarium and their toxins in Swedish oats and revealed significant annual and regional differences. This is the first study of the so-called emerging mycotoxins (e.g., ENNs, MON and BEA) in oats grown in Sweden.