Margit Schollenberger

Fusarium toxins in wheat flour collected in an area in southwest Germany

A total of 60 samples of wheat flour were collected during the first 6 months of 1999 from mills and food stores in an area in southwest Germany. Samples included whole-grain and two types of white flour with these three groups characterized by a high, medium and low ash content. The contents of deoxynivalenol (DON), nivalenol (NIV), 3- and 15-acetyldeoxynivalenol, HT-2 toxin (HT-2), T-2 toxin (T-2) and fusarenon-X (FUS-X) were determined by gas chromatography/mass spectrometry, and those of zearalenone (ZEA), alpha- and beta-zearalenol (alpha- and beta-ZOL) by high performance liquid chromatography with fluorescence detection. FUS-X, alpha- and beta-ZOL were not detected in any sample. Based on incidence and level, DON was the predominant toxin followed by NIV and ZEA for all three flour types. The overall degree of toxin contamination was lower with decreasing ash content. This suggests a localization of the toxins analyzed primarily in the outer parts of the original wheat kernels. The median DON content was significantly (P<0.05) higher for wheat flour originating from wheat of conventional than of organic production.

Determination of eight trichothecenes by gas chromatography–mass spectrometry after sample clean-up by a two-stage solid-phase extraction

A method is described for the determination of eight trichothecenes of type A and B in a variety of complex matrices including heavily moulded and pigmented cereals, whole cereal ears, cereal-based foods, mixed feeds and faeces from swine. Trichothecenes were determined as their trifluoroacetyl derivatives by gas chromatography with ion-trap mass spectrometry detection operating in chemical ionization mode. Isobutane was chosen as reactant gas and optimum parameters of measurement were determined. For sample preparation a clean-up procedure was developed using a combination of Florisil and cation-exchange cartridges for solid-phase extraction. Limits of detection and quantification as well as recoveries are described.

Deoxynivalenol and Nivalenol Production by Fusarium culmorum Isolates Differing in Aggressiveness Toward Winter Rye.

ABSTRACT A susceptible synthetic winter rye population was inoculated with 42 isolates of Fusarium culmorum, originating from nine European countries and Australia, at two field locations in Germany. Significant (P = 0.01) genetic variation in aggressiveness of isolates of F. culmorum was observed across both field locations. Field samples were used to determine deoxynivalenol (DON), nivalenol (NIV), and ergosterol (ERG) contents. The 42 isolates also were incubated on rye grain in vitro, and DON and NIV contents were analyzed. Thirty-four isolates produced DON, and seven isolates produced NIV at both field locations and in vitro. Mean DON contents ranged from 0.5 to 64.6 mg/kg in grain from field trials and from 0.3 to 376.3 mg/kg in grain incubated in vitro; mean NIV contents ranged from 17.6 to 30.4 mg/kg in grain from field trials and from 0.8 to 381.0 mg/kg in grain incubated in vitro. No correlation was found between the DON content of field-grown grain and grain incubated in vitro. NIV-producing isolates originated from the Netherlands, Germany, Italy, and Australia. More aggressive isolates produced higher mean DON contents in grain in field trials (r = 0.69; P = 0.01). However, DON production rate per unit of fungal biomass, estimated as the DON/ERG ratio at harvest, was not correlated with aggressiveness. Toxin production seemed to be a common feature in F. culmorum. In vitro assays reliably distinguished DON- and NIV-producing types of F. culmorum; however, these assays could not predict production of DON by these isolates in the field.

A survey of Fusarium toxins in cereal-based foods marketed in an area of southwest Germany

A total of 237 commercially available samples of cereal-based foods including bread and related products, noodles, breakfast cereals, baby and infant foods, rice and other foods were randomly collected in southwest Germany during the first six months of 1998. The trichothecenes deoxynivalenol (DON), 3-and 15-acetyl-deoxynivalenol (3-,15-ADON), nivalenol (NIV), fusarenon-X (FUS-X), T-2 toxin (T-2) and HT-2 toxin (HT-2) were determined by gaschromatography/mass spectrometry following clean-up by a two stage solid-phase extraction. Detection limits ranged between 2 and 12 μg/kg. Based on all samples, the incidence of DON, HT-2, T-2, 3-ADON,15-ADON, and NIV was at 71, 18, 4, 4, 4 and 2%, respectively; the average contents in positive samples were at 103, 16, 14, 17, 24 and 109 μg/kg,respectively. Fus-X was not detected in any sample. A lower (P < 0.05) DON content was found in baby and infant foods as well as in cookies and cakes compared to bread. Overall, based on the incidence and level of all six toxins, the degree of contamination was lowest in baby and infant foods. Foods produced from either white or whole grain flour did not differ (P > 0.05) with regard to the incidence and level of DON. In foods produced from cereals of organic production both the incidence and median content of DON was lower compared to conventional production. Zearalenone, α- and β-zearalenol were determined by high performance liquid chromatography in 20 selected samples, mostly baby and infant foods. These toxins were not present in excess of the detection limit in any sample.

Effects of Fusarium toxin-contaminated wheat and feed intake level on the biotransformation and carry-over of deoxynivalenol in dairy cows

An experiment was carried out to examine the effects of feeding Fusarium toxin-contaminated wheat (8.21 mg deoxynivalenol (DON) and 0.09 mg zearalenone (ZON) per kg dry matter) at different feed intake levels on the biotransformation and carry-over of DON in dairy cows. For this purpose, 14 ruminal and duodenal fistulated dairy cows were fed a diet containing 60% concentrate with a wheat portion of 55% (Fusarium toxin-contaminated wheat (mycotoxin period) or control wheat (control period)) and the ration was completed with maize- and grass silage (50 : 50) on a dry matter basis. Daily DON intakes ranged from 16.6 to 75.6 mg in the mycotoxin period at dry matter intakes of 5.6–20.5 kg. DON was almost completely biotransformed to de-epoxy DON (94–99%) independent of the DON/feed intake, and the flow of DON and de-epoxy DON at the duodenum related to DON intake ranged from 12 to 77% when the Fusarium toxin-contaminated wheat was fed. In the serum samples, de-epoxy DON was detected in the range of 4–28 ng ml−1 in the mycotoxin period, while concentrations of DON were all below the detection limit. The daily excretion of DON and de-epoxy DON in the milk of cows fed the contaminated wheat varied between 1 and 10 µg and between 14 and 104 µg, respectively. The total carry-over rates as the ratio between the daily excretion of DON and de-epoxy DON into milk and DON intake were in the ranges of 0.0001–0.0002 and 0.0004–0.0024, respectively. Total carry-over rates of DON as DON and de-epoxy DON into the milk increased significantly with increasing milk yield. In the urine samples, de-epoxy DON was the predominant substance as compared with DON with a portion of the total DON plus de-epoxy DON concentration to 96% when the Fusarium toxin-contaminated wheat was fed, whereas the total residues of DON plus de-epoxy DON in faeces ranged between 2 and 18% of DON intake in the mycotoxin period. The degree of glucuronidation of de-epoxy DON was found to be approximately 100% in serum. From 33 to 80% of DON and from 73 to 92% of de-epoxy DON, and from 21 to 92% of DON and from 86 to 100% of de-epoxy DON were glucuronidated in the milk and urine, respectively. It is concluded that DON is very rapidly biotransformed to de-epoxy DON in the rumen and only negligible amounts of DON and de-epoxy DON were transmitted into the milk within the range of 5.6–20.5 kg day−1 dry matter intake and milk yields (fat corrected milk) between 10 and 42 kg day−1.

Mycotoxins in food systems in Sub Saharan Africa: A review.

Mycotoxins, toxic secondary metabolites of fungi are now recognised as major cause of food intoxications in Sub Saharan Africa (SSA). Aflatoxins, the most important of the group have been implicated in acute aflatoxicoses, carcinogenicity, growth retardation, neonatal jaundice and immunological suppression in SSA. The hot and humid tropical climate provides ideal condition for growth of toxigenicAspergillus spp, making food contamination to be widespread in SSA, with maize and groundnuts being the most contaminated. The available data suggests that cassava products (the most important African food) are not prone to aflatoxin contamination. Recent data on ochratoxin A produced by species ofAspergillus on grains have indicated the necessity for it to be monitored in SSA. Fumonisins represent the most importantFusarium mycotoxins in SSA, and surveillance data indicate very high contamination rates of almost 100% in maize samples from West Africa. Limited information exists on the occurrence of trichothecenes, while the data currently available suggest that zearalenone contamination seems not to be a problem in SSA. The strategies under investigation to mitigate the mycotoxin problem in SSA include education of the people on the danger of consuming mouldy foods, pre and post harvest management strategies with emphasis on biological control, use of plant products to arrest fungal growth during storage, enterosorbent clay technology, and the search for traditional techniques that could reduce/detoxify mycotoxins during food processing.

Variation in chemical composition and physical characteristics of cereal grains from different genotypes

ABSTRACT Genotypes of cereal grains, including winter barley (n = 21), maize (n = 27), oats (n = 14), winter rye (n = 22), winter triticale (n = 21) and winter wheat (n = 29), were assayed for their chemical composition and physical characteristics as part of the collaborative research project referred to as GrainUp. Genotypes of one grain species were grown on the same site, except maize. In general, concentrations of proximate nutrients were not largely different from feed tables. The coefficient of variation (CV) for the ether extract concentration of maize was high because the data pool comprised speciality maize bred for its high oil content. A subset of 8 barley, 20 rye, 20 triticale and 20 wheat samples was analysed to differ significantly in several carbohydrate fractions. Gross energy concentration of cereal grains could be predicted from proximate nutrient concentration with good accuracy. The mean lysine concentration of protein was the highest in oats (4.2 g/16 g N) and the lowest in wheat (2.7 g/16 g N). Significant differences were also detected in the concentrations of macro elements as well as iron, manganese, zinc and copper. Concentrations of arsenic, cadmium and lead were below the limit of detection. The concentration of lower inositol phosphates was low, but some inositol pentaphosphates were detected in all grains. In barley, relatively high inositol tetraphosphate concentration also was found. Intrinsic phytase activity was the highest in rye, followed by triticale, wheat, barley and maize, and it was not detectable in oats. Substantial differences were seen in the thousand seed weight, test weight, falling number and extract viscoelasticity characteristics. The study is a comprehensive overview of the composition of different cereal grain genotypes when grown on the same location. The relevance of the variation in composition for digestibility in different animal species will be subject of other communications.

Fusarium toxins of the scirpentriol subgroup: a review

Scirpentriol and its seven acetylated derivatives comprise a family of type-A trichothecene toxins produced by several species of Fusarium fungi. Out of this group 4,15-diacetoxyscirpenol has attracted most attention. It elicits toxic responses in several species and was detected in a variety of substrates. Out of the three possible monoacetylated derivatives 15-monoacetoxyscirpenol and the parent alcohol scirpentriol received some attention, whereas the remaining members of the family were mentioned in few reports. The present review deals with the structure, biosynthesis, analysis and toxicity of scirpentriol toxins. Formation by Fusarium species as well as culture conditions used for toxigenicity studies are reviewed; data about the natural occurrence of scirpentriol toxins in different cereal types, cereal associated products as well as in non-grain matrices including potato and soya bean are reported. Basing on literature reports about the toxicity of scirpentriol toxins an attempt is made to summarise the state of knowledge for risk evaluation for human and animal health.

Hydrolysis of phytate and formation of inositol phosphate isomers without or with supplemented phytases in different segments of the digestive tract of broilers.

The objective was to characterise degradation of myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) (InsP6) and formation of inositol phosphate (InsP) isomers in different segments of the broiler digestive tract. Influence of an Aspergillus niger (PhyA) and two Escherichia coli-derived (PhyE1 and PhyE2) phytases was also investigated. A total of 600 16-d-old broilers were allocated to forty floor pens (ten pens per treatment). Low-P (5·2 g/kg DM) maize–soyabean meal-based diets were fed without (basal diet; BD) or with a phytase added. On day 25, digesta from different digestive tract segments were pooled per segment on a pen-basis, freeze-dried and analysed for P, InsP isomers and the marker TiO2. InsP6 degradation until the lower ileum (74 %) in BD-fed birds showed a high potential of broilers and their gut microbiota to hydrolyse InsP6 in low-P diets. Different InsP patterns in different gut segments suggested the involvement of phosphatases of different origin. Supplemented phytases increased InsP6 hydrolysis in the crop (P < 0·01) but not in the lower ileum. Measurements in the crop and proventriculus/gizzard confirmed published in vitro degradation pathways of 3- and 6-phytases for the first time. In the intestinal segments, specifically formed InsP4–5 isomers of supplemented phytases were still present, indicating further activity of these enzymes. Myo-inositol tetrakisphosphate (InsP4) accumulation differed between PhyE1 and PhyE2 compared with PhyA in the anterior segments of the gut (P < 0·01). Thus, the hydrolytic cleavage of the first phosphate group is not the only limiting step in phytate degradation in broilers.

Serum IgA-Promoting Effects Induced by Feed Loads Containing Isolated Deoxynivalenol (DON) in Growing Piglets

Deoxynivalenol (DON), a Fusarium toxin belonging to the trichothecene group, has been reported to produce a variety of adverse health effects in farm animals, such as inhibition of protein synthesis, reduction of feed intake, and alteration of the immune system. In pigs, the effects of increasing levels of chemically pure DON in a semisynthetic diet on performance, health, and serum immunglobulin A (IgA) levels were examined. A diet, without grain components and trichothecene free (8 main trichothecenes), with doses of 0, 300, 600, and 1200 μg pure DON/kg was fed to 34 female pigs for a period of 8 wk after weaning under standardized conditions. Body weight gain and biochemical and hematological values in the blood and serum, including concentrations of IgA, blood glucose, cortisol, and insulinlike growth factor 1 (IGF-1), were determined. Increasing levels of DON in the feed induced a significant depression of glucose levels. Cortisol and IGF-1 levels were not significantly affected but differed between groups at the end of the experiment. A significant increase of IgA concentration in the serum even at a dosage level of 600 μg DON/kg feed was observed. This is the first report demonstrating in vivo that limited dosages of DON are able to stimulate IgA levels in the serum of growing piglets.