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

Impact of Environmental Conditions on the Concentrations of Trichothecenes, Their Glucosides, and Emerging Fusarium Toxins in Naturally Contaminated, Irradiated, and Fusarium langsethiae Inoculated Oats

Trichothecenes produced by Fusarium species are commonly detected in oats. However, the ratios of the concentrations of free trichothecenes and their conjugates and how they are impacted by different interacting environmental conditions are not well documented. This study aims to examine the effect of water activity (0.95 and 0.98 aw) and temperature (20 and 25 °C) stress on the production of T-2 and HT-2 toxins, deoxynivalenol and their conjugates, as well as diacetoxyscirpenol (DAS). Multiple mycotoxins were detected using liquid chromatography-tandem mass spectrometry from 64 contaminated oat samples. The highest concentrations of HT-2-glucoside (HT-2-Glc) were observed at 0.98 aw and 20 °C, and were higher than other type A trichothecenes in the natural oats' treatments. However, no statistical differences were found between the mean concentrations of HT-2-Glc and HT-2 toxins in all storage conditions analysed. DAS concentrations were generally low and highest at 0.95 aw and 20 °C, while deoxynivalenol-3-glucoside levels were highest at 0.98 aw and 20 °C in the naturally contaminated oats. Emerging mycotoxins such as beauvericin, moniliformin, and enniatins mostly increased with a rise in water activity and temperature in the naturally contaminated oats treatment. This study reinforces the importance of storage aw and temperature conditions in the high risk of free and modified toxin contamination of small cereal grains.

Co-occurrence of T-2 and HT-2 Mycotoxins and α and β Anomers of Their Glucosides in Wheat and Oat Grains

The aim of this study was to simultaneously determine T-2 and HT-2 toxins and the α and β anomers of their glucosides to assess their content in wheat and oat grains harvested in Poland (2020-2022). Of 298 wheat samples, only 14 (5%) contained the sum of the T-2 and HT-2 toxins (average 34.2 μg/kg; 10.6-67.7 μg/kg). In oat (n = 129), these compounds were detected much more frequently (70% of samples) at an average level of 107.5 μg/kg (6.9-949.1 μg/kg). The sum of T-2 and HT-2 glucosides was detectable in 3% of the wheat (average 16.3 μg/kg; 7.1-39.4 μg/kg) and 65% of the oat samples (average 35.1 μg/kg; 4.0-624.1 μg/kg). Following the study, T-2-3-α-glucoside was identified as the only naturally occurring anomer, while both anomers of HT-2-3-glucosides were detected with higher contents and occurrence rates of HT-2-3-β-glucoside than the α anomer of this compound.

Melatonin protects Leydig cells from HT-2 toxin-induced ferroptosis and apoptosis via glucose-6-phosphate dehydrogenase/glutathione -dependent pathway

HT-2 toxin is a mycotoxin commonly found in food and water that can have adverse effects on male reproductive systems, including testosterone secretion. Ferroptosis and apoptosis are two types of programmed cell death that have been implicated in the regulation of cellular functions. Melatonin, a powerful antioxidant with various physiological functions, has been shown to regulate testosterone secretion. However, the mechanisms underlying the protective effects of melatonin against HT-2 toxin-induced damage in testosterone secretion are not fully understood. In this study, we investigated the effects of HT-2 toxin on sheep Leydig cells and the potential protective role of melatonin. We found that HT-2 toxin inhibited cell proliferation and testosterone secretion of Leydig cells in a dose-dependent manner and induced ferroptosis and apoptosis through intracellular reactive oxygen species accumulation, leading to lipid peroxidation. Exposure of Leydig cells to melatonin in vitro reversed the defective phenotypes caused by HT-2 toxin via a glucose-6-phosphate dehydrogenase/glutathione-dependent mechanism. Interference of glucose-6-phosphate dehydrogenase disrupted the beneficial effect of melatonin on ferroptosis and apoptosis in HT-2 toxin-treated Leydig cells. Furthermore, similar results were observed in vivo in the testes of male mice injected with HT-2 toxin with or without melatonin treatment for 30 days. Our findings suggest that melatonin inhibits ferroptosis and apoptosis by elevating the expression of glucose-6-phosphate dehydrogenase to eliminate reactive oxygen species accumulation in HT-2 toxin-treated Leydig cells. These results provide fundamental evidence for eliminating the adverse effects of HT-2 toxin on male reproduction.

Temporal and spatial dynamics of Fusarium spp. and mycotoxins in Swedish cereals during 16 years

We analysed the dynamics of Fusarium spp. and mycotoxin contamination in Swedish cereals during 2004–2018. More than 1400 cereal samples from field trials were included, collected in a monitoring programme run by the Swedish Board of Agriculture. Five Fusarium mycotoxins were quantified with LC-MS/MS and fungal DNA from four species was quantified using quantitative real-time PCR. Correlation analyses revealed that deoxynivalenol (DON) and zearalenone (ZEN) were mainly associated with Fusarium graminearum, but stronger correlations with F. culmorum was seen some years. Nivalenol (NIV) was associated with F. poae and the HT-2 and T-2 toxins with F. langsethiae. Clear differences in mycotoxin contamination between different cereal crops and geographical regions were identified. The highest levels of DON and ZEN were found in spring wheat in Western Sweden. For NIV, HT-2 and T-2 toxins, the levels were highest in spring oats and spring barley. Regional differences were not detected for NIV, while HT-2 and T-2 toxins were associated with the northernmost region. We found that delayed harvest was strongly associated with increased levels of DON and ZEN in several crops. However, harvest date did not influence the levels of NIV or HT-2 and T-2 toxins. Our results suggest similar distribution patterns of DON and ZEN, in contrast to NIV and HT-2 and T-2 toxins, probably mirroring the differences in the ecology of the toxin-producing Fusarium species. Timely harvest is important to reduce the risk of DON and ZEN contamination, especially for fields with other risk factors.

Survey of Freshly Harvested Oat Grains from Southern Brazil Reveals High Incidence of Type B Trichothecenes and Associated Fusarium Species

The current study investigated the fungal diversity in freshly harvested oat samples from the two largest production regions in Brazil, Paraná (PR) and Rio Grande do Sul (RS), focusing primarily on the Fusarium genus and the presence of type B trichothecenes. The majority of the isolates belonged to the Fusarium sambucinum species complex, and were identified as F. graminearum sensu stricto (s.s.), F. meridionale, and F. poae. In the RS region, F. poae was the most frequent fungus, while F. graminearum s.s. was the most frequent in the PR region. The F. graminearum s.s. isolates were 15-ADON genotype, while F. meridionale and F. poae were NIV genotype. Mycotoxin analysis revealed that 92% and 100% of the samples from PR and RS were contaminated with type B trichothecenes, respectively. Oat grains from PR were predominantly contaminated with DON, whereas NIV was predominant in oats from RS. Twenty-four percent of the samples were contaminated with DON at levels higher than Brazilian regulations. Co-contamination of DON, its derivatives, and NIV was observed in 84% and 57.7% of the samples from PR and RS, respectively. The results provide new information on Fusarium contamination in Brazilian oats, highlighting the importance of further studies on mycotoxins.

A Two-Year Occurrence of Fusarium T-2 and HT-2 Toxin in Croatian Cereals Relative of the Regional Weather

To investigate into the T-2 and HT-2 toxin occurrence, 240 samples of unprocessed cereals (maize, wheat, barley, and oats) were sampled from different fields located in three Croatian regions during 2017-2018. In all samples, sum concentrations of T-2/HT-2 toxin were determined using the ELISA method, while the LC-MS/MS was used as a confirmatory method for both mycotoxins in positive samples (>LOD) and the establishment of T-2 over HT-2 toxin ratios. The results showed oats to be the most contaminated cereal, with T-2/HT-2 toxins detected in 70.0% of samples, followed by barley (40.9%), maize (26.8%) and wheat (19.2%), with the mean T-2/HT-2 ratio ranging from 1:2.7 in maize to 1:4.4 in oats. Sum T-2/HT-2 concentrations in two maize samples were higher than the indicative level recommended by the European Commission, necessitating subsequent investigations into the conditions under which these poorly investigated mycotoxins are produced. Statistically significantly (p < 0.05) higher concentrations of T-2/HT-2 toxin were determined in oats throughout study regions as compared to those found in wheat, but not maize and barley, while the concentrations of these mycotoxins were related to the regional weather in Croatia.

Removal of Small Kernels Reduces the Content of Fusarium Mycotoxins in Oat Grain

Cereal grain contaminated by Fusarium mycotoxins is undesirable in food and feed because of the harmful health effects of the mycotoxins in humans and animals. Reduction of mycotoxin content in grain by cleaning and size sorting has mainly been studied in wheat. We investigated whether the removal of small kernels by size sorting could be a method to reduce the content of mycotoxins in oat grain. Samples from 24 Norwegian mycotoxin-contaminated grain lots (14 from 2015 and 10 from 2018) were sorted by a laboratory sieve (sieve size 2.2 mm) into large and small kernel fractions and, in addition to unsorted grain samples, analyzed with LC-MS-MS for quantification of 10 mycotoxins. By removing the small kernel fraction (on average 15% and 21% of the weight of the samples from the two years, respectively), the mean concentrations of HT-2+T-2 toxins were reduced by 56% (from 745 to 328 µg/kg) in the 2015 samples and by 32% (from 178 to 121 µg/kg) in the 2018 samples. Deoxynivalenol (DON) was reduced by 24% (from 191 to 145 µg/kg) in the 2018 samples, and enniatin B (EnnB) by 44% (from 1059 to 594 µg/kg) in the 2015 samples. Despite low levels, our analyses showed a trend towards reduced content of DON, ADON, NIV, EnnA, EnnA1, EnnB1 and BEA after removing the small kernel fraction in samples from 2015. For several of the mycotoxins, the concentrations were considerably higher in the small kernel fraction compared to unsorted grain. Our results demonstrate that the level of mycotoxins in unprocessed oat grain can be reduced by removing small kernels. We assume that our study is the first report on the effect of size sorting on the content of enniatins (Enns), NIV and BEA in oat grains.

Trichothecenes in Cereal Grains - An Update

Trichothecenes are sesquiterpenoid mycotoxins produced by fungi from the order Hypocreales, including members of the Fusarium genus that infect cereal grain crops. Different trichothecene-producing Fusarium species and strains have different trichothecene chemotypes belonging to the Type A and B class. These fungi cause a disease of small grain cereals, called Fusarium head blight, and their toxins contaminate host tissues. As potent inhibitors of eukaryotic protein synthesis, trichothecenes pose a health risk to human and animal consumers of infected cereal grains. In 2009, Foroud and Eudes published a review of trichothecenes in cereal grains for human consumption. As an update to this review, the work herein provides a comprehensive and multi-disciplinary review of the Fusarium trichothecenes covering topics in chemistry and biochemistry, pathogen biology, trichothecene toxicity, molecular mechanisms of resistance or detoxification, genetics of resistance and breeding strategies to reduce their contamination of wheat and barley.

Mycobiota and Mycotoxic Contamination of Feed Cereals

The cereals are a suitable substrate for the growth of microscopic filamentous fungi. Micromycetes are capable of reducing the nutritional value of feedstuff and they can produce several mycotoxins. The most frequent genera of microscopic filamentous fungi are Fusarium, Penicillium, Alternaria and Aspergillus. The contamination by microscopic fungi and mycotoxins was determinated in 56 samples of feed cereals originating from the Slovak Republic. The most common genera of fungi detected in the feed cereals included: Alternaria (67.8 %), Fusarium (44.6 %), Penicillium (39.2 %), Mucor (30.3 %), Rhizopus (28.5 %), Cladosporium (21.4 %), Scopulariopsis (8.9 %) and Aspergillus (1.7 %). Deoxynivalenol was present in 24 samples (42.8 %) and zearalenone in 15 samples (26.7 %). The values of both mycotoxins did not reach the regulatory limits and thus they do not pose a risk to livestock nutrition.

Risk of Exposure to Multiple Mycotoxins from Maize-Based Complementary Foods in Tanzania

This study estimated exposure to multiple mycotoxins in 249 infants aged between 6 and 12 months in three agro-ecological zones of Tanzania. Maize-based complementary food intakes were estimated using two 24 h dietary recalls. Using @Risk software, probabilistic exposure assessment was conducted by modeling maize intake data (kg/kg body weight/day) with previously determined multiple mycotoxin (except for ochratoxin A (OTA) and zearalenone (ZEA), present in only a few samples) contamination data (μg/kg) in maize. Maize intakes ranged from 0.13 to 185 g/child/day (average = 59 ± 36 g/child/day). The estimated mean exposures were higher for aflatoxins (6-fold), fumonisins (3-fold), and deoxynivalenol (2-fold) than health-based guidance values of 0.017 ng/kg body weight/day, 2 μg/kg body weight/day, and 1 μg/kg body weight/day, respectively. The population at risk of exposures above the limits of health concern ranged from 12% for HT-2 toxin through 35% for deoxynivalenol to 100% for aflatoxins. The exposure varied among the agro-ecological zones. Strategies targeting multiple mycotoxins in maize are urgently needed to minimize exposures in Tanzania.

Mycotoxins content and its association with changing patterns of Fusarium pathogens in wheat in the Czech Republic

Mycotoxin content in 244 samples of wheat ears randomly collected during 2014 and 2015 from various localities in the Czech Republic was analysed using liquid chromatography coupled to mass spectrometry (LC-MS). Mean mycotoxin concentration in 2014 was highest for deoxynivalenol (DON; 760 μg/kg), followed by zearalenone (ZEA; 115 μg/kg), 3-acetyldeoxynivalenol (3-ADON; 88 μg/kg), deoxynivalenol-3-glucoside (83 μg/kg), and enniatins (ENNs; 102 μg/kg). In 2015, DON (66 μg/kg) also had the highest concentration level, followed by ENNs (35 μg/kg), nivalenol (2 μg/kg), and beauvericin (2 μg/kg). The maximum limit for DON in the European Union (1,250 μg/kg) was exceeded in 2% of samples, and the maximum limit for ZEA (100 μg/kg) was exceeded in 0.8% of samples. Fusarium species causing head blight were identified using PCR assays. During 2014-2015, Fusarium poae considerably dominated (48.7% average value of occurrence in the samples). Other species were detected in much lower frequencies in both years: Fusarium graminearum (average frequency of occurrence 13.7%), Fusarium avenaceum (11.9%), Fusarium culmorum (4.2%), and Fusarium equiseti (2.9%). Fusarium langsethiae was identified only in 2015, at a frequency of 10.2%, and Fusarium sporotrichioides was present only sporadically in 2014.

Impact of Mechanical and Thermal Energies on the Degradation of T-2 and HT-2 Toxins during Extrusion Cooking of Oat Flour

The type A trichothecenes T-2 toxin (T-2) and HT-2 toxin (HT-2) are naturally occurring toxic food contaminants, with the highest concentrations found in contaminated oats. The influence of thermal food processing on these toxins is poorly understood, and only a few publications address the degradation rates. Therefore, we systematically investigated the degradation of T-2 and HT-2 during both laboratory and industrial-scale extrusion cooking of oats. Extrusion cooking under laboratory conditions was performed with oats fortified with T-2 or HT-2 as well as with naturally contaminated oat flour dust. The experiments were designed according to industrial conditions in terms of temperature, water content, pressure, residence time, and oat content. Flour mixtures containing naturally contaminated oats were used for industrial-scale processing. Degradation rates under laboratory conditions were up to 59.6 ± 1.51 and 47.2 ± 0.53% for T-2 and HT-2, respectively, in fortified extrudates but were decreased to 35.1 ± 1.55 and 22.0 ± 4.68% when naturally contaminated flour samples were used. The results show a higher degradation of T-2 during extrusion cooking than of HT-2. Moisture content, mechanical shear, and temperature showed an impact on the toxin degradation and can be optimized to counteract food contamination.

Changes in the Fusarium Head Blight Complex of Malting Barley in a Three-Year Field Experiment in Italy

In this study, conducted for three years on eleven malting barley varieties cultivated in central Italy, the incidence of different mycotoxigenic fungal genera, the identification of the Fusarium species associated with the Fusarium Head Blight (FHB) complex, and kernels contamination with deoxynivalenol (DON) and T-2 mycotoxins were determined. The influence of climatic conditions on Fusarium infections and FHB complex composition was also investigated. Fusarium species were always present in the three years and the high average and maximum temperatures during anthesis mainly favored their occurrence. The FHB complex was subject to changes during the three years and the main causal agents were F. poae, F. avenaceum, F. tricinctum and F. graminearum, which, even if constantly present, never represented the principal FHB agent. The relative incidence of Fusarium species changed because of climatic conditions occurring during the seasons. The FHB complex was composed of many different Fusarium species and some of them were associated with a specific variety and/or with specific weather parameters, indicating that the interaction between a certain plant genotype and climatic conditions may influence the presence of Fusarium spp. causing infections. With regard to mycotoxin contamination, T-2 toxin, in some cases, was found in kernels at levels that exceeded EU recommended values.

Deoxynivalenol Exposure in Norway, Risk Assessments for Different Human Age Groups

Deoxynivalenol (DON) is the most common mycotoxin in Norwegian cereals, and DON is detected in most samples of crude cereal grain and cereal food commodities such as flour, bran, and oat flakes. The Norwegian Scientific Committee for Food Safety assessed the risk for adverse effects of deoxynivalenol (DON) in different age groups of the domestic population. This review presents the main results from the risk assessment, supplemented with some recently published data. Impairment of the immune system together with reduced feed intake and weight gain are the critical effects of DON in experimental animals on which the current tolerable daily intake was established. Based on food consumption and occurrence data, the mean exposure to DON in years with low and high levels of DON in the flour, respectively, were in the range of or up to two times the Tolerable Daily Intake (TDI) in 1-year-old infants and 2-year-old children. In years with high mean DON concentration, the high (95th-percentile) exposure exceeded the TDI by up to 3.5 times in 1-, 2- , 4-, and 9-year-old children. The assessment concluded that exceeding the TDI in infants and children is of concern. The estimated dietary DON intakes in adolescent and adult populations are in the range of the TDI or below, and are not a health concern. Acute human exposure to DON is not of concern in any age group.

Multiplex Dipstick Immunoassay for Semiquantitative Determination of Fusarium Mycotoxins in Oat

A multiplex competitive antibody-based assay in a dipstick format for the simultaneous detection of major of Fusarium mycotoxins in oats is described. Ground oats sample is extracted with a mixture of methanol and water. Sample extract is diluted and directly analyzed by a multiplex dipstick. The test kit employs a microwell of reagents containing antibodies linked to gold particles and a dipstick made up of a nitrocellulose membrane were specific capture lines are located. In the presence of oats extract each antibody binds the corresponding mycotoxin before starting to run vertically on the dipstick in the direction of the capture lines. In 10 min red lines rise from the background on the dipstick. Results are interpreted by an optical reader measuring the ratio between each test line and a control line located on the top of the strip.

Co-Occurrence of Regulated, Masked and Emerging Mycotoxins and Secondary Metabolites in Finished Feed and Maize-An Extensive Survey

Global trade of agricultural commodities (e.g., animal feed) requires monitoring for fungal toxins. Also, little is known about masked and emerging toxins and metabolites. 1926 samples from 52 countries were analysed for toxins and metabolites. Of 162 compounds detected, up to 68 metabolites were found in a single sample. A subset of 1113 finished feed, maize and maize silage samples containing 57 compounds from 2012 to 2015 from 44 countries was investigated using liquid chromatography and mass spectrometry. Deoxynivalenol (DON), zearalenone (ZEN) and fumonisins showed large increases of annual medians in Europe. Within a region, distinct trends were observed, suggesting importance of local meteorology and cultivars. In 2015, median DON concentrations increased to 1400 μ g·kg - 1 in Austria, but were stable in Germany at 350 μ g·kg - 1 . In 2014, enniatins occurred at median concentrations of 250 μ g·kg - 1 in Europe, at levels similar to DON and ZEN. The latter were frequently correlated with DON-3-glucoside and ZEN-14-sulfate. Co-occurrence of regulated toxins was frequent with e.g., enniatins, and moniliformin. Correlation was observed between DON and DON-3-glucoside and with beauvericin. Results indicate that considerably more than 25% of agricultural commodities could be contaminated with mycotoxins as suggested by FAO, although this is at least partly due to the lower limits of detection in the current survey. Observed contamination percentages ranged from 7.1 to 79% for B trichothecenes and 88% for ZEN.

Updated survey of Fusarium species and toxins in Finnish cereal grains

The aim of the project was to produce updated information during 2005-14 on the Fusarium species found in Finnish cereal grains, and the toxins produced by them, as the last comprehensive survey study of Fusarium species and their toxins in Finland was carried out at the turn of the 1960s and the 1970s. Another aim was to use the latest molecular and chemical methods to investigate the occurrence and correlation of Fusarium species and their mycotoxins in Finland. The most common Fusarium species found in Finland in the FinMyco project 2005 and 2006 were F. avenaceum, F. culmorum, F. graminearum, F. poae, F. sporotrichioides and F. langsethiae. F. avenaceum was the most dominant species in barley, spring wheat and oat samples. The occurrence of F. culmorum and F. graminearum was high in oats and barley. Infection by Fusarium fungi was the lowest in winter cereal grains. The incidence of Fusarium species in 2005 was much higher than in 2006 due to weather conditions. F. langsethiae has become much more common in Finland since 2001. F. graminearum has also risen in the order of importance. A highly significant correlation was found between Fusarium graminearum DNA and deoxynivalenol (DON) levels in Finnish oats, barley and wheat. When comparing the FinMyco data in 2005-06 with the results of the Finnish safety monitoring programme for 2005-14, spring cereals were noted as being more susceptible to infection by Fusarium fungi and the formation of toxins. The contents of T-2 and HT-2 toxins and the frequency of exceptionally high DON concentrations all increased in Finland during 2005-14. Beauvericin (BEA), enniatins (ENNs) and moniliformin (MON) were also very common contaminants of Finnish grains in 2005-06. Climate change is leading to warmer weather, and this may indicate more changes in Finnish Fusarium mycobiota and toxin contents and profiles in the near future.

A non-linear model for temperature-dependent sporulation and T-2 and HT-2 production of Fusarium langsethiae and Fusarium sporotrichioides

This research has produced new quantitative data on the sporulation and T-2+HT-2 toxin production that could be further integrated to develop a comprehensive disease or toxin prediction model for Fusarium langsethiae and Fusarium sporotrichioides. Experiments were conducted to determine the effect of temperature or incubation time on sporulation and the effect of temperature on T-2+HT-2 toxin production of strains of the two species. F. sporotrichioides demonstrated a preference for higher temperatures than F. langsethiae during sporulation; the optimum temperature was 24.5 ± 0.7 °C for F. langsethiae and 32.3 ± 2.1 °C for F. sporotrichioides, according to the Beta equation fitted to the data. The dynamics of sporulation over different incubation times were fitted by a Gompertz function. The maximum spore production was estimated to be after 18 and 8 d incubation at optimum temperatures for F. langsethiae and F. sporotrichioides, respectively. F. sporotrichioides produced more T-2+HT-2 than F. langsethiae. The best fit of the effect of temperature on T-2+HT-2 production in wheat grains was obtained with a Beta equation showing an optimum temperature of 14.7 ± 0.8 °C for F. langsethiae and 12.1 ± 0.2 °C for F. sporotrichioides. The optimum temperature for mycotoxin production was lower than for sporulation.

Gizzard erosion and ulceration syndrome in chickens and turkeys: a review of causal or predisposing factors

Gizzard erosion and ulceration syndrome (GEU) was described for the first time in the 1930s. The main focus of early studies was on nutritional deficiencies and peroxidation of highly polyunsaturated fatty acids as causative factors. During the 1970s and 1980s the focus was moved towards toxic substances in the feed. Scott's review in 1985 concluded that overproduction of gastric acid induced by gizzerosine was a major cause of GEU. During the last decades, serotype 1 of fowl adenovirus A and Clostridium perfringens have been implicated as important pathogenic agents in the development of GEU in chickens. Although GEU is globally distributed and its subclinical form appears to be common in commercial poultry flocks, the condition is rarely mentioned in standard textbooks on poultry health. This regrettable fact is probably due in part to the lack of one definitive cause of the syndrome.

Determination of T-2 and HT-2 toxins in food and feed: an update

Based on the recent scientific opinion of the European Food Safety Authority (EFSA) Panel on Contaminants in the Food Chain on the risks to human and animal health related to the presence of T-2 and HT-2 toxins in food and feed that was published by EFSA in the EFSA Journal, this article provides an update on the determination of these Fusarium mycotoxins. After a brief introduction into the chemistry of these toxins, both chromatographic and immuno-analytical methods are discussed for the determination of these type A trichothecenes. During the last decade, liquid chromatography with (tandem) mass spectrometry has become the most frequently used method for the determination of T-2 and HT-2 toxins, often within a multi-analyte approach. However, complex matrices and the resulting signal suppression effects, as observed particularly in electrospray-mass spectrometry methods owing to matrix effects, may require careful optimisation of clean-up, usage of matrix matched standards, or e.g. the use of internal standards. For specific purposes where extremely low limits of quantification are needed, e.g. for the analysis of duplicate diets, a dedicated gas chromatography method with multistage mass spectrometry has become available. Other novel analytical approaches to determine T-2 and HT-2 toxins in food and feed include biosensor-based methods in surface plasmon resonance and electrochemical formats, as well as DNA microchip assays. For rapid screening, several immunochemical methods (mostly ELISAs) have become available and some are sold as commercial test kits. Whereas these methods work fast, cross-reactivities with other trichothecenes can have an undesired effect on their accuracy. While proficiency tests including T-2 and HT-2 toxins have been carried out, none of the chromatographic or immunochemical methods have been formally validated in interlaboratory validation studies. There are no certified reference materials available for T-2 and HT-2 toxins.

Comparative effects of fungicides and environmental factors on growth and T-2 + HT-2 toxin production by Fusarium sporotrichioides and Fusarium langsethiae strains on an oat-based matrix

The objective of this study was to compare the effect of the fungicides prochloraz and tebuconazole (0-1 µg/ml) on lag phase, growth rate, and T-2 + HT-2 toxin production by strains of Fusarium sporotrichioides and Fusarium langsethiae on oat-based media under different conditions of water activity (aw; 0.98 and 0.95) × temperature (15 and 25 °C). Relative effective dose values for the fungicides required to inhibit growth by 50% (ED50) and 90% (ED90) and T-2 + HT-2 production were determined. The lag phases prior to growth were prolonged at the marginal aw × temperature conditions tested and by the presence of the fungicides. The growth rates of F. sporotrichioides and F. langsethiae were similarly inhibited by prochloraz compared with the controls. However, in the presence of tebuconazole, F. langsethiae was much more tolerant with very little inhibitory effects of the fungicide. The ED50 values ranged from 0.08 to ≯1.0 µg/ml for prochloraz and from 0.34 to ≯1.0 µg/ml for tebuconazole in the case of F. sporotrichioides. For F. langsethiae, these values were 0.09 to ≯1.0 and 0.31 to ≯1.0 µg/ml at the two temperatures and aw levels tested. Prochloraz (0.2-0.4 µg/ml) effectively inhibited toxin production at 15 °C and the two aw levels examined. However, at 25 °C the fungicide was less effective, regardless of the aw level. For tebuconazole, there were significant differences in efficacy against the F. sporotrichioides and F. langsethiae strains. The latter species produced consistently higher amounts of T-2 + HT-2 toxin at both 15 and 25 °C and 0.98 aw. The differential tolerance to the fungicides between the fungal species is discussed in terms of growth and toxin production.

Temporal Variation of Mycotoxin Producing Fungi in Norwegian Cereals

Spring barley is grown on about half of the Norwegian cereal area. The rest of the area is equally divided between wheat and oats. Most years the domestic production provides 70%–80% of the domestic market for bread wheat. Barley and oats are mainly grown for animal feed. During the years 2008–2012, severe epidemics of Fusarium head blight have led to increased mycotoxin contamination of cereals. During that period, precipitation was above normal during anthesis and grain maturation. The most important mycotoxin producers have been F. avenaceum, F. culmorum, F. graminearum and F. langsethiae. Increased deoxynivalenol contamination of Norwegian cereals during recent years is due to severe F. graminearum epidemics.

Assessment and introduction of quantitative resistance to Fusarium head blight in elite spring barley

Breeding for resistance is a key task to control Fusarium head blight (FHB), a devastating disease of small cereals leading to economic losses and grain contamination with mycotoxins harmful for humans and animals. In the present work, FHB resistance of the six-rowed spring barley 'Chevron' to FHB in Germany was compared with those of adapted German spring barley cultivars. Both under natural infection conditions and after spray inoculation with conidia of Fusarium culmorum, F. sporotrichioides, and F. avenaceum under field conditions, Chevron showed a high level of quantitative resistance to the infection and contamination of grain with diverse mycotoxins. This indicates that Chevron is not only a little susceptible to deoxynivalenol-producing Fusarium spp. but also to Fusarium spp. producing type A trichothecenes and enniatins. Monitoring the initial infection course of F. culmorum on barley lemma tissue by confocal laser-scanning microscopy provided evidence that FHB resistance of Chevron is partially mediated by a preformed penetration resistance, because direct penetration of floral tissue by F. culmorum was observed rarely on Chevron but was common on susceptible genotypes. Alternatively, F. culmorum penetrated Chevron lemma tissue via stomata, which was unusual for susceptible genotypes. We generated double-haploid barley populations segregating for the major FHB resistance quantitative trait loci (QTL) Qrgz-2H-8 of Chevron. Subsequently, we characterized these populations by spray inoculation with conidia of F. culmorum and F. sporotrichioides. This suggested that Qrgz-2H-8 was functional in the genetic background of European elite barley cultivars. However, the degree of achieved resistance was very low when compared with quantitative resistance of the QTL donor Chevron, and the introgression of Qrgz-2H-8 was not sufficient to mediate the cellular resistance phenotype of Chevron in the European backgrounds.

A survey of trichothecenes, zearalenone and patulin in milled grain-based products using GC-MS/MS

An analytical protocol based on QuEChERS and gas chromatography-tandem mass spectrometry (GC-MS/MS) was successfully applied for the determination of trichothecenes, patulin and zearalenone in 182 milled grain-based samples. The analytical method was validated following the SANCO 1495/2011 document. LOQs were lower than 10μgkg(-1) for the selected mycotoxins. Recoveries of fortified cereals ranged between 76-108% and 77-114% at 20 and 80μgkg(-1), respectively, with relative standard deviation lower than 9%. More than 60% of the samples analysed showed deoxynivalenol contamination, followed by HT-2 toxin and nivalenol with frequencies of 12.1% and 10.4%, respectively. Co-occurrence of mycotoxins was also present in major cereals. A risk characterisation was carried out based on probable daily intake (PDI) and tolerable daily intake (TDI). Despite PDI of the average consumers were below TDI, special attention should be paid in high consumers as well as other susceptible population.

Deoxynivalenol and other selected Fusarium toxins in Swedish wheat--occurrence and correlation to specific Fusarium species

Wheat is often infected by Fusarium species producing mycotoxins, which may pose health risks to humans and animals. Deoxynivalenol (DON) is the most important Fusarium toxin in Swedish wheat and has previously been shown to be produced mainly by Fusarium graminearum. However, less is known about the co-occurrence of DON and F. graminearum with other toxins and Fusarium species in Sweden. This study examined the distribution of the most important toxigenic Fusarium species and their toxins in winter wheat (2009 and 2011) and spring wheat (2010 and 2011). DNA from seven species was quantified with qPCR and the toxin levels were quantified with a multitoxin analysis method based on liquid chromatography/electrospray ionisation-tandem mass spectrometry (HPLC/ESI-MS/MS). The method enabled detection of many fungal metabolites, including DON, zearalenone (ZEA), nivalenol (NIV), T-2 toxin, HT-2 toxins, moniliformin (MON), beauvericin (BEA), and enniatins (ENNs). It was found that Fusarium poae and Fusarium avenaceum were present in almost all samples. Other common Fusarium species were F. graminearum and F. culmorum, present in more than 70% of samples. Several species occurred at lower DNA levels in 2011 than in other years, but the reverse was true for F. graminearum and Fusarium langsethiae. The most prevalent toxins were ENNs, present in 100% of samples. DON was also common, especially in spring wheat, whereas ZEA and NIV were common in 2009 and in winter wheat, but less common in 2011 and in spring wheat. Only three samples of spring wheat contained T-2 or HT-2 above LOQ. Annual mean levels of several mycotoxins were significantly lower in 2011 than in other years, but the reverse applied for DON. The strongest correlations between mycotoxin and Fusarium DNA levels were found between F. avenaceum and ENNs (r(2) = 0.67) and MON (r(2) = 0.62), and F. graminearum and DON (r(2) = 0.74). These results show that several Fusarium species and toxins co-occur in wheat. The highest toxin levels were detected in spring wheat and DON and ENNs, the latter belonging to the group of so called "emerging toxins", which were the most prevalent toxins and those occurring at the highest levels.

Chicken cytochrome P450 1A5 is the key enzyme for metabolizing T-2 toxin to 3'OH-T-2

The transmission of T-2 toxin and its metabolites into the edible tissues of poultry has potential effects on human health. We report that T-2 toxin significantly induces CYP1A4 and CYP1A5 expression in chicken embryonic hepatocyte cells. The enzyme activity assays of CYP1A4 and CYP1A5 heterologously expressed in HeLa cells indicate that only CYP1A5 metabolizes T-2 to 3'OH-T-2 by the 3'-hydroxylation of isovaleryl groups. In vitro enzyme assays of recombinant CYP1A5 expressed in DH5α further confirm that CYP1A5 can convert T-2 into TC-1 (3'OH-T-2). Therefore, CYP1A5 is critical for the metabolism of trichothecene mycotoxin in chickens.

Analysis of T-2 and HT-2 toxins in oats and other cereals by means of HPLC with fluorescence detection

Bearing in mind the high toxicity of T-2 and HT-2 toxins which occur in cereals (mainly in oats) EU plans legal limits for these mycotoxins. The occurrence data are insufficient because reliable and sensitive analysis methods are not available.A sensitive HPLC gradient method was developed which is applicable with common HPLC equipment (HPLC with fluorescence detection). After extraction of the toxins from sample matrix with methanol/water the diluted extracts were cleaned-up using immunoaffinity columns and then derivatized with 1-anthroylnitrile/DMAP. The T-2 and HT-2 toxins were separated from peaks of the cereal matrix and derivatization reagent by means of a relatively complex HPLC gradient method. The method was validated for oats, wheat, rye, barley, and maize. The recovery rates were in the range of 70-99%, the precision (RSDR) of 3-8%. The limits of detection of T-2 and HT-2 toxins were 1 μg/kg. A total of 119 samples of cereals and cereal products was analyzed according to the optimized method. The analyses of 54 samples of dehulled oats and of 11 samples of processed oat products from food industry had a contamination frequency of 100%. The contents (sum of T-2 and HT-2 toxins) amounted to 3 to 174 μg/kg for the dehulled oats and to 4 to 48 μg/kg for the processed oat products. 29 samples of maize and maize products had a contamination frequency of 80% (2-106 μg/kg in the sum of T-2 and HT-2 toxins). In the samples of wheat and barley the toxins were detected only occasionally (contents: 1-10 μg/kg), in rye not at all.

The natural occurrence of T-2 toxin and fumonisins in maize samples in Croatia

Maize (Zea mays) considered to be one of the most frequent crops in Croatia, is often contaminated with Fusarium mycotoxins. The aim of this study was to investigate the possible contamination of maize with T-2 toxin and fumonisins on 46 samples from different regions of Croatia. The highest concentrations of T-2 toxin and fumonisins were 210 and 25,200 ng/g, with mean values of 110 and 4,509 ng/g, respectively, pointing to maize contamination with these mycotoxins after the period of the year with extremely high rainfall.

Contamination level of T-2 and HT-2 toxin in cereal crops from Aba area in Sichuan Province, China

The contamination level of T-2 and HT-2 toxin in cereal crops from Aba area in Sichuan Province of China was investigated by rapid liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The results revealed the high incidence of T-2 and HT-2 toxin and relatively low contamination level in the samples. The incidence of HT-2 toxin was 49.74% and its average level was 3.746 μg/kg. The incidence of toxin was 11.64% and the average level was 0.565 μg/kg. The maximum of T-2 and HT-2 toxin concentration was 3.332 and 34.510 μg/kg, respectively. In addition, contaminated samples not only included homegrown products, but included external purchased rice and flour, which may be attributed to bad storage environment and sanitary conditions.

Mycotoxin production of Fusarium langsethiae and Fusarium sporotrichioides on cereal-based substrates

The present study investigated and compared the mycotoxin production of two Fusarium species, F. sporotrichioides and F. langsethiae, isolated from grain samples. Fusarium strains were cultivated at 25°C for 7 days on two types of solid media, i.e. rice-flour and cereal-flour agar. Toxins produced were measured after the incubation period with a multi-mycotoxin method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS). Both F. sporotrichioides and F. langsethiae synthesised type-A trichothecenes, i.e. T-2 and HT-2 toxins, diacetoxyscirpenol (DAS) and neosolaniol (NEO). In addition, both species could be verified as beauvericin producers. The toxin production occurred in both cereal-based assays but was more predominant on the carbohydrate-rich rice-flour medium. The two species were potent producers of T-2 toxin, the highest amounts measured being at a level of 20,000 μg/kg after 7 days' incubation. Differences between the species were observed regarding the quantitative production of the other trichothecenes: F. sporotrichioides was a more prolific producer of HT-2 toxin and beauvericin, whereas F. langsethiae produced higher amounts of DAS and NEO. On rice-flour assay, the toxin production was monitored during the growth period. The production started rapidly at an early growth phase and several toxins could be detected already after the 1st day of incubation, the highest concentrations being at mg/kg level. The results also indicated that the biosynthesis by F. sporotrichioides and F. langsethiae shifted towards the other type-A trichothecenes at the expense of T-2 toxin at the end of the cultivation.

Hydrogen-bonding interactions in T-2 toxin studied using solution and solid-state NMR

The structure of T-2 toxin in the solid-state is limited to X-ray crystallographic studies, which lack sufficient resolution to provide direct evidence for hydrogen-bonding interactions. Furthermore, its solution-structure, despite extensive Nuclear Magnetic Resonance (NMR) studies, has provided little insight into its hydrogen-bonding behavior, thus far. Hydrogen-bonding interactions are often an important part of biological activity. In order to study these interactions, the structure of T-2 toxin was compared in both the solution- and solid-state using NMR Spectroscopy. It was determined that the solution- and solid-state structure differ dramatically, as indicated by differences in their carbon chemical shifts, these observations are further supported by solution proton spectral parameters and exchange behavior. The slow chemical exchange process and cross-relaxation dynamics with water observed between the hydroxyl hydrogen on C-3 and water supports the existence of a preferential hydrogen bonding interaction on the opposite side of the molecule from the epoxide ring, which is known to be essential for trichothecene toxicity. This result implies that these hydrogen-bonding interactions could play an important role in the biological function of T-2 toxin and posits towards a possible interaction for the trichothecene class of toxins and the ribosome. These findings clearly illustrate the importance of utilizing solid-state NMR for the study of biological compounds, and suggest that a more detailed study of this whole class of toxins, namely trichothecenes, should be pursued using this methodology.