A survey on the occurrence of Fusarium mycotoxins in Bavarian cereals from the 1987 harvest

Reaction of winter wheat (Triticum aestivum L.) cultivars to infection with Fusarium spp.: mycotoxin contamination in grain and chaff

This study compares the susceptibility of winter wheat (Triticum aestivum L.) cultivars to Fusarium head blight (FHB) and accumulation of mycotoxins in kernels and chaff under different climatic conditions in two locations-Cerekwica near Poznan (Central West Poland) and Sitaniec, near Zamosc, Lublin region (South East Poland). Very high variations were found in the concentrations of mycotoxins (zearalenone, ZEA; nivalenol, NIV; deoxynivalenol, DON; moniliformin, MON) in examined fractions: Fusarium-damaged kernels (FDK) and healthy looking kernels (HLK) and in chaff for individual cultivars in both locations. In most cases, significantly higher concentrations of investigated toxins were recorded in wheat from the area of Lublin than from Poznan (p < 0.05). The highest Fusarium infection rates and mycotoxin biosynthesis levels were observed in the Lublin location, with the percentage of the FDK fraction ranging 8.1-81.6. In this region, ZEA concentration (microg g(-1)) after inoculation with F. culmorum and F. graminearum ranged from 0.02-0.48 and 0.32-1.04, respectively. In the Poznan area, the toxin concentrations were considerably lower, ranging 0.01-0.10 and 0.03-0.13 microg g(-1) for both isolates, respectively. The concentration of DON was significantly higher than ZEA or NIV levels. The levels of MON accumulation (microg g(-1)) in the FDK fraction were between 0.14 and 1.73 (Poznan area) and ND (not detected) to 2.51 (Lublin area). F. avenaceum infection rate ranged 7-35% in samples where the toxin was detected.

Fumonisin B1 and zearalenone contamination of wheat in Croatia and influence of fungicide treatments

In Croatia, a trial was conducted to determine the presence of theFusariummycotoxins fumonisin B1and zearalenone in wheat kernels and to evaluate the efficacy of nine fungicides on Fusarium head blight severity as well as fumonisin B1and zearalenone accumulation in wheat grain. Fumonisin B1and zearalenone were detected in all grain samples in mean concentrations ranging from 182.0 to 446.6 µg kg-1(fumonisin B1) and from 2.59 to 5.33 µg kg-1(zearalenone). No significant differences were found among fumonisin B1and zearalenone content in wheat grain for the different fungicide treatments. No correlation was revealed between Fusarium head blight severity and fumonisin B1or zearalenone content in wheat grain, nor between fungicide efficacy and fumonisin B1or zearalenone content in wheat grain. Under conditions of high disease pressure, efficacy of the fungicides was between 85.7% (tebuconazole + triadimefon) and 72.1% (carbendazim).

Mycotoxins nivalenol and deoxynivalenol differentially modulate cytokine mRNA expression in Jurkat T cells

Deoxynivalenol (DON) and its hydroxylated form nivalenol (NIV) are Fusarium mycotoxins that occur in cereal grains alone or in combination. Several studies have shown that these metabolites affect lymphocyte functions. However, the molecular mechanisms underlying their activities are still partially known. To address this issue, we examined the influence of NIV and DON in modulating IFNgamma, IL-2 and IL-8 mRNA levels in Jurkat T cells. In PMA/ionomycin stimulated cells, pre-incubated with increasing concentrations of NIV, transcription was induced in the range 0.06-2 microM; higher concentrations of NIV were found non-stimulating (4 microM) or inhibitory (8 microM) for IFNgamma and IL-2 whereas IL-8 was still induced. DON administration elicited a similar profile for IL-8 and IFNgamma, whilst IL-2 mRNA was induced in a broader range of concentrations. Combination of NIV and DON at 1:1 and 1:10 ratios essentially restored the cytokine transcriptional pattern observed with NIV alone but the level of transcripts, with the exception of IL-8, peaked at lower concentrations suggesting interactive effects. Moreover both mycotoxins caused inhibition of cell proliferation, mediated by induction of apoptosis, confirming previous results and highlighting the usefulness of Jurkat as a T-cell model to study the effects of mycotoxins on the immune functions in humans.

Natural occurrence of mycotoxins in staple cereals from Ethiopia

The occurrence of mycotoxins in barley, sorghum, teff (Eragrostis tef) and wheat from Ethiopia has been studied. Samples were analyzed for aflatoxin B(1) (AFB1), ochratoxin A (OTA), deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEN) using high performance liquid chromatography (HPLC) and for fumonisins (FUM) using enzyme linked immunosorbent assay (ELISA). AFB1 and OTA were detected in samples of all the four crops. AFB1 was detected in 8.8% of the 352 samples analyzed at concentrations ranging from trace to 26 microg kg(-1). OTA occurred in 24.3% of 321 samples at a mean concentration of 54.1 microg kg(-1) and a maximum of 2106 microg kg(-1). DON occurred in barley, sorghum and wheat at 40-2340 microg kg(-1) with an overall incidence of 48.8% among the 84 mainly 'suspect' samples analyzed; NIV was co-analyzed with DON and was detected at 40 microg kg(-1) in a wheat sample and at 50, 380, and 490 microg kg(-1) in three sorghum samples. FUM and ZEN occurred only in sorghum samples with low frequencies at concentrations reaching 2117 and 32 microg kg(-1), respectively. The analytical results indicate higher mycotoxin contamination in sorghum, which could be related to the widespread storage of sorghum grain in underground pits leading to elevated seed moisture contents. This is the first report on the occurrence of OTA in teff.

Accumulation of type A trichothecenes in maize, wheat and rice by Fusarium sporotrichioides isolates under diverse culture conditions

Toxigenic isolates of Fusarium sporotrichioides were tested for the production of type A trichothecenes (T-2 toxin, HT-2 toxin, diacetoxyscirpenol and neosolaniol) when grown on three substrates (maize, rice and wheat) under various conditions of temperature and water activity in the laboratory for 3 weeks. Trichothecenes were determined by high-performance liquid chromatography with fluorescence detection, after derivatisation with coumarin-3-carbonyl chloride. This is the first time this analytical method has been applied to an extensive study of trichothecene accumulation. With minor exceptions, greater trichothecene production occurred when samples were incubated at 20 degrees C and moistened with 35% water (water activity 0.990) although incubation conditions affected the substrates studied in different ways. No correlation between the different pairs of trichothecenes was found except for neosolaniol and diacetoxyscirpenol (r=0.56). Principal component analysis results show that the data points can be grouped in three rough clusters related to cereal type, which points out that the composition of these cereals can influence the production of type A trichothecenes.

Quantification of deoxynivalenol in wheat using an immunoaffinity column and liquid chromatography

A simple and accurate method to quantify the mycotoxin deoxynivalenol (DON) in wheat is described. The method uses immunoaffinity chromatography for DON isolation and liquid chromatography (LC) for toxin detection and quantification. Wheat samples are extracted in water, filtered twice and applied to an immunoaffinity column. Following a water wash, DON is eluted from the column with methanol and injected onto an LC system with a UV detector for quantification. Test performance was evaluated in terms of antibody specificity, limit of detection, percentage recovery, precision, column capacity, assay linearity and comparison with the GC-electron-capture detection (ECD) method of Tacke and Casper. Specificity of the immunoaffinity column cleanup procedure was confirmed with only DON (>80%) and its 15-C derivatives (40-50%) being recognized by the antibody while 3-C DON derivatives, nivalenol, T-2 and fusarenon-X did not bind. The limit of detection is at least 0.10 microg/g. Percentage recovery for the entire assay range averages 90% with an average relative standard deviation of 8.3%. Naturally contaminated samples showed comparable precision. Column capacity was determined to be 3.3 microg. The assay showed a high degree of linearity (r2=0.999) and an optimum assay range of 0.10 to 10.0 microg/g. Comparative analysis of 28 naturally or artificially contaminated wheat samples using DONtest-HPLC and the GC-ECD method of Tacke and Casper showed that DONtest-HPLC is a statistically significant predictor of the GC-ECD method (r2=0.982).

[Comparative investigations of mycotoxological status of alternatively and conventionally grown crops]

100 samples of rye and 101 samples of wheat coming out of both conventional and alternative or ecological production were investigated for contamination with mycotoxins with interest for our degree of latitude. Deoxynivalenol (DON) was found with thin-layer-chromatography in 131 of 201 samples altogether. A top level of 1250 micrograms DON kg-1 in rye of alternative offspring was detected. The average burden in contaminated rye coming from ecological production was 427 micrograms kg-1 and a mean level of 160 micrograms kg-1 resulting in rye out of conventional growth conditions. In wheat, conventionally grown yield showed slightly lower contamination (mean levels of 420 micrograms DON kg-1 towards 486 micrograms kg-1). The toxins 3-acetyl-deoxynivalenol, nivalenol and fusarenone X were detected in some samples by thin-layer-chromatography. This results could not be confirmed by gas chromatography -mass spectrometry. Zearalenone was found in 40 out of the number of 201 samples of grain by HPLC with fluorescence detection. An average of 6 micrograms and 24 micrograms zearalenone kg-1 in conventionally and alternatively grown wheat and 4 micrograms and 51 micrograms zearalenone kg-1 in conventionally and alternatively produced rye was detected. The highest finding of zearalenone was 199 micrograms kg-1 in alternatively grown rye. Skin toxicity testing did not show any reference of contamination with type-A-trichothecenes. No correlation between contamination of zearalenone or deoxynivalenol and thousand-kernel-weight was detected.

Use of monoclonal antibodies for the analysis of mycotoxins

Hybridomas producing monoclonal antibodies against aflatoxin M1, ochratoxin A, zearalenone, T-2 toxin, diacetoxyscirpenol, 3-acetyl-deoxynivalenol, fusarenon X, and roridin A were developed after immunization of BALB/c mice and fusion of the splenocytes with myeloma cells. The antibodies were characterized in terms of immunoglobulin subclass, sensitivity, and specificity. The use of these antibodies in competitive enzyme immunoassays, either as microtiter plate assays or membrane-based quick tests, as well as for the production of immunoaffinity columns is described. The advantages and disadvantages of monoclonal antibodies compared to polyclonal antisera for the improvement of mycotoxin analysis are discussed.

[Effect of the fungicide matador (tebuconazole/triadimenol) on mycotoxin production by Fusarium culmorum]

Applications of the fungicide Matador to winter wheat (Slejpner) inoculated at earing with Fusarium culmorum resulted in a considerable decrease in the incidence of Fusarium headblight. In the study presented here, subsequent mycotoxin analyses by selected ion monitoring gas chromatography-mass spectrometry revealed higher levels of nivalenol (NIV) in samples singly treated with Matador at 1 L/ha. Amounts as high as 2432 micrograms NIV/kg and 860 micrograms NIV/kg, representing a 16- or six-fold increase as compared to controls, were found in wheat treated with the fungicide 3 h before or 24 h after inoculation of the grain with F. culmorum, respectively. In parallel, higher cytotoxic activities of these samples were obtained when testing crude sample extracts in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-cell culture bioassay using swine kidney monolayers as target cells. It is concluded that treatment of grain with the fungicide Matador could result in a marked stimulation of the production of NIV by F. culmorum. As the incidence of Fusarium headblight did not correlate with the amount of mycotoxins found, the need for mycotoxin analyses combined with bioassays such as the MTT-cell culture assay is recommended for a meaningful assessment of the quality of grain treated in such a manner.

Studies on the application of enzyme immunoassays for the Fusarium mycotoxins deoxynivalenol, 3-acetyldeoxynivalenol, and zearalenone

Polyclonal antisera against zearalenone (ZEA) were produced in rabbits after immunization with ZEA-oxime coupled to human serum albumin. Using these antibodies and a ZEA-oxime-horseradish peroxidase conjugate in a competitive direct enzyme immunoassay (EIA), the detection limit for ZEA was 70 pg/ml. The relative cross-reactivities of the assay with ZEA, alpha-zearalenol, beta-zearalenol, zearalanone, alpha-zearalanol, and beta-zearalanol, respectively, were 100%, 37.3%, 7.2%, 59.2%, 5.3%, and 3.9%, respectively. This EIA and two EIAs for deoxynivalenol (DON) and 3-acetyldeoxynivalenol(3-AcDON) (Usleber et al., 1991) were used to analyze wheat samples. The limits of determination for DON, 3-AcDON, and ZEA in wheat were 200 ppb, 50 ppb, and 20 ppb, respectively. The analysis of reference materials (wheat flour) containing DON by EIA showed good agreement with the nominal values. The EIA for ZEA was in addition used to analyze biological fluids, obtained during a feeding trial. Two lactating cows were administered 25 mg and 100 mg ZEA per day, respectively, over a period of 6 days. Serum, milk, urine, and feces were assayed in the ZEA-EIA with and without sample treatment with beta-glucuronidase prior to the analysis. Maximum toxin levels (ZEA-equivalents) found in milk were 0.4 and 1.2 ppb (glucuronides). The toxin concentration in milk decreased rapidly after the last toxin administration. In the urine, maximum levels of toxin-glucuronide conjugates were 23 ppb and 24 ppb, respectively. The serum toxin levels corresponded to those found in milk. In the feces, mean values were 150 ppb and 500 ppb, respectively, no conjugated toxins were found in feces.

[The significance of the mycotoxins desoxynivalenol, zearalenone and ochratoxin A for agricultural domestic animals]

Mycotoxins are metabolic products of mycotoxins which have various chemical structures and show various toxic effects. Deoxynivalenol (vomitoxin) is an important economic factor in pig production due to growth depression and suppression of the immune system. Previous studies have shown that the 1-ppm limit in the sole feed for pigs should not be exceeded. Studies of methods of detoxification have as yet not produced conclusive results. Zearalenone has an tolerable effect and may lead to fertility disturbances on the oestrogen production in pigs and can cause remarkable economic damage even in the ppb range. Recommendations of upper limits cannot be made on the basis of the available results. The kidney toxin ochratoxin A is of importance in pig and poultry breeding and--due to its accumulation in the tissue--represents a possible source of danger to man. Since a possible carcinogenic effect of the toxin cannot be excluded, its content in animal rations should be kept as low as possible. For ruminants mycotoxins as a whole do not represent a particular source of danger as these substances can be degraded or converted by rumen flora.

Influence of subchronic exposure to low dietary deoxynivalenol, a trichothecene mycotoxin, on intestinal absorption of nutrients in mice

During a 6-wk feeding trial, effects of low dietary deoxynivalenol (DON; 0, 0.1, 1 and 10 ppm) on food consumption and weight gain were investigated in male mice. Food intake was similar in all four dietary groups. Weight gain in the group receiving 10 ppm DON was significantly (P less than 0.01) reduced. At the end of the feeding period, test animals were sacrificed and absorption of water, D-glucose, L-leucine, L-tryptophan, 5-methyltetrahydrofolic acid and iron was measured in isolated perfused jejunal segments in vitro. No effects were observed on absorption of water, leucine, tryptophan and iron. However, at a dietary DON concentration of 10 ppm, a slightly but significantly (P less than 0.05) reduced transfer of glucose was measured. Furthermore, transfer as well as tissue accumulation of 5-methyltetrahydrofolic acid in the jejunal segment were both significantly decreased up to 50%. Heavy metal and trace element content was determined in liver, kidney and small intestine. Manganese and molybdenum content in liver tissue was reduced with a DON concentration of 10 ppm in the diet. The findings indicate that subchronic ingestion of DON, in concentrations occurring in contaminated food and feed, results in an impairment of intestinal transfer and uptake of nutrients such as glucose and 5-methyltetrahydrofolic acid.

A survey of the natural occurrence of Fusarium mycotoxins in cereals grown in New Zealand in 1986-1989

Fusarium mycotoxins, principally trichothecenes, occurred commonly in grain from crops in the North Island of New Zealand, but were much less common and also at the much lower levels in grains from South Island regions. The principal contaminants were trichothecenes of the nivalenol (NIV) and deoxynivalenol (DON) types. Trichothecenes derived from scirpentriol and T-2 tetraol were not common. Moniliformin occurred very rarely, while zearalenone contamination was not uncommon, but the levels were generally low. Maize kernels were commonly contaminated by moderate levels of both NIV- and DON-type trichothecenes, with levels up to 3.6 mg/kg and 11.95 mg/kg respectively recorded. The occurrence of NIV-type trichothecenes as a general contaminant in the range of 0.3-0.8 mg/kg, and frequently as the main contaminant, is unusual.