Natural contamination of spring barley with group A trichothecene mycotoxins in south-eastern Poland

Natural Co-Occurrence of Mycotoxins in Foods and Feeds and Their in vitro Combined Toxicological Effects

Some foods and feeds are often contaminated by numerous mycotoxins, but most studies have focused on the occurrence and toxicology of a single mycotoxin. Regulations throughout the world do not consider the combined effects of mycotoxins. However, several surveys have reported the natural co-occurrence of mycotoxins from all over the world. Most of the published data has concerned the major mycotoxins aflatoxins (AFs), ochratoxin A (OTA), zearalenone (ZEA), fumonisins (FUM) and trichothecenes (TCTs), especially deoxynivalenol (DON). Concerning cereals and derived cereal product samples, among the 127 mycotoxin combinations described in the literature, AFs+FUM, DON+ZEA, AFs+OTA, and FUM+ZEA are the most observed. However, only a few studies specified the number of co-occurring mycotoxins with the percentage of the co-contaminated samples, as well as the main combinations found. Studies of mycotoxin combination toxicity showed antagonist, additive or synergic effects depending on the tested species, cell model or mixture, and were not necessarily time- or dose-dependent. This review summarizes the findings on mycotoxins and their co-occurrence in various foods and feeds from all over the world as well as in vitro experimental data on their combined toxicity.

Fusarium phytotoxin trichothecenes have an elicitor-like activity in Arabidopsis thaliana, but the activity differed significantly among their molecular species

Phytopathogenic fungi such as Fusarium spp. synthesize trichothecene family phytotoxins. Although the type B trichothecene, deoxynivalenol (DON), is thought to be a virulence factor allowing infection of plants by their trichothecene-producing Fusarium spp., little is known about effects of trichothecenes on the defense response in host plants. Therefore, in this article, we investigated these effects of various trichothecenes in Fusarium-susceptible Arabidopsis thaliana. Necrotic lesions were observed in Arabidopsis leaves infiltrated by 1 microM type A trichothecenes such as T-2 toxin. Trichothecene-induced lesions exhibited dead cells, callose deposition, generation of hydrogen peroxide, and accumulation of salicylic acids. Moreover, infiltration by trichothecenes caused rapid and prolonged activation of two mitogen-activated protein kinases and induced expression of both PR-1 and PDF1.2 genes. Thus, type A trichothecenes trigger the cell death by activation of an elicitor-like signaling pathway in Arabidopsis. Although DON did not have such an activity even at 10 microM, translational inhibition by DON was observed at concentrations above 5 microM. These results suggested that DON is capable of inhibiting translation in Arabidopsis cells without induction of the elicitor-like signaling pathway.

Natural occurrence of scirpentriol in cereals infected by Fusarium species

Wheat, barley and oat grain samples naturally contaminated with Fusarium spp. were analysed for the presence of scirpentriol (STO). This toxin was detected in 1, 37 and 8% of 248 wheat, 32 barley and 99 oat grain samples, respectively, and the maximum concentration was 83 microg x kg(-1). Samples of wheat and oat grain with visible scab symptoms were also analysed, and STO (mean level 255 microg x kg(-1)) was detected only in oat samples infected with F. sporotrichioides and F. poae as the dominant species. We analysed 15 barley samples that were subdivided based on seed size into fractions of <2.5 and > 2.5 mm in diameter. The smaller kernels contained an average 94% of the STO in the samples (in kernel fraction > 2.5 mm 28 microg x kg(-1), <2.5 mm 297 microg x kg(-1)). In oats, STO levels were highest in the chaff, lower in the stalk's apical internode and lowest in the grain.

Natural contamination of oat with group A trichothecene mycotoxins in Poland

Ninety-nine naturally contaminated oat grain samples were collected in 12 plant breeding stations in different parts of Poland. T-2 toxin, HT-2 toxin and diacetoxyscirpenol (DAS) levels were determined by gas chromatography with mass selective detection (GC-MS). HT-2 was the major toxin with an incidence of 24% and its average level in positive samples was 21 microg kg(-1). The incidence of T-2 and DAS was 15 and 12%, and their average levels were 60 and 23 microg kg(-1), respectively. The highest concentrations of HT-2, T-2 and DAS were 47, 703 and 111 microg kg(-1), respectively. Sixty-five samples were free of detectable amounts of the toxic metabolites analysed.

The occurrence of HT-2 toxin and other trichothecenes in Norwegian cereals

A total of 449 grain samples, 102 barley, 169 wheat and 178 oat samples were collected from different regions of Norway from 1996-1998 crops, mainly from grain loads and silos. The samples were analysed for type A and B trichothecenes, the largest groups of mycotoxins produced by the Fusarium species, by gas chromatography with mass spectrometric detection (GC-MS). Factors affecting the presence of the different trichothecenes are discussed. Deoxynivalenol (DON) and HT-2 toxin were the trichothecenes most frequently detected, followed by T-2 toxin, nivalenol, and scirpentriol, scirpentriol being detected only in seven samples (> 20 micrograms/kg). Oats were the grain species most heavily contaminated with an incidence (% > 20 micrograms/kg) and mean concentration of positive samples of 70% (115 micrograms/kg) for HT-2 toxin, 30% (60 micrograms/kg) for T-2 toxin, 57% (104 micrograms/kg) for DON, and 10% (56 micrograms/kg) for nivalenol. The corresponding values for barley were 22% (73 micrograms/kg), 5% (85 micrograms/kg), 17% (155 micrograms/kg) and 6% (30 micrograms/kg), and for wheat 1.2% (20 micrograms/kg), 0.6% (20 micrograms/kg), 14% (53 micrograms/kg) and 0% for HT-2, T-2, DON and nivalenol, respectively. Norwegian oats were found to contain HT-2 and T-2 toxin in concentrations that might be at threat to human health for high consumers of oats. The amount of DON was significantly lower than in the crop from previous years.

Occurrence of trichothecenes in Argentinean beer: a preliminary exposure assessment

The presence of trichothecenes (deoxynivalenol, 3-acetyl deoxynivalenol, 15-acetyl deoxynivalenol, nivalenol, neosolaniol and diacetoxyscirpenol) was studied in 50 samples of Argentinean beer (nine different brands). Gas chromatography with electron capture detector was used for identification and quantification of these mycotoxins. The only mycotoxin detected was deoxynivalenol (DON). It was present in 44% of the samples, 18% were contaminated with more than 20 ng/ml. Toxin levels ranged from 4 to 221 ng/ml in positive samples. This is the first report on DON contamination of Argentinean beer. The estimate of probable daily intake (PDI) of DON from beer consumption in Argentina does not indicate a health hazard, but it has to be taken into account in calculations of total DON exposure in the population.