Economic losses and decontamination

Bacterial Enrichment Cultures Biotransform the Mycotoxin Deoxynivalenol into a Novel Metabolite Toxic to Plant and Porcine Cells

The mycotoxin deoxynivalenol (DON), produced in wheat, barley and maize by Fusarium graminearum and Fusarium culmorum, is threatening the health of humans and animals. With its worldwide high incidence in food and feed, mitigation strategies are needed to detoxify DON, maintaining the nutritional value and palatability of decontaminated commodities. A promising technique is biological degradation, where microorganisms are used to biotransform mycotoxins into less toxic metabolites. In this study, bacterial enrichment cultures were screened for their DON detoxification potential, where DON and its potential derivatives were monitored. The residual phytotoxicity was determined through a bioassay using the aquatic plant Lemna minor L. Two bacterial enrichment cultures were found to biotransform DON into a still highly toxic metabolite for plants. Furthermore, a cytotoxic effect was observed on the cellular viability of intestinal porcine epithelial cells. Through liquid chromatography high-resolution mass spectrometry analysis, an unknown compound was detected, and tentatively characterized with a molecular weight of 30.0 Da (i.e., CH₂O) higher than DON. Metabarcoding of the subsequently enriched bacterial communities revealed a shift towards the genera Sphingopyxis, Pseudoxanthomonas, Ochrobactrum and Pseudarthrobacter. This work describes the discovery of a novel bacterial DON-derived metabolite, toxic to plant and porcine cells.

Railway-Associated Attractants as Potential Contaminants for Wildlife

Grizzly bears (Ursus arctos) appear to be attracted to natural and anthropogenic forage along railways, which may increase collision vulnerability, but also potentially causes exposure to contaminants associated with railway infrastructure. We assessed contaminant exposure for a vulnerable population of grizzly bears in the Canadian Rocky Mountains by determining if (1) dandelions (Taraxacum officinale) growing adjacent to a railway and grain spilled from hopper cars contain heavy metals, polycyclic aromatic hydrocarbons (PAHs), and mycotoxins and (2) metal concentrations from hair samples of individual bears correlates with use of the railway or other anthropogenic features. We used principle components analysis to represent 10 heavy metals and 16 PAHs and then compared their concentrations in railway-associated sources of grain and dandelions to reference samples that we purchased (grain) or sampled from nearby sites (dandelions). We also measured metal concentrations in the hair of bears that were captured and fitted with GPS collars. We found significantly higher concentrations in railway-associated samples of dandelion and grain for both metals (particularly lead, iron, and chromium), and the sum of 16 PAHs. Several metals and PAHs in railway-associated samples exceeded regulatory standards for soil or animal feed. Mycotoxins were detectable in grain samples, but occurred well below permissible standards. Metal concentrations in bear hair were not predicted by railway use, but higher metal concentrations occurred in male bears and two individuals that used ski hills during fall. As mitigation to reduce wildlife exposure to contaminants, particularly in protected areas, we encourage removal of railway grain deposits, regular maintenance of railway infrastructure, such as lubricating stations, and investigation of contaminants associated with other human infrastructures, such as ski hills.

Mycotoxicoses in veterinary medicine: Aspergillosis and penicilliosis

Molds and mycotoxins are contaminants of animal feed causing spoilage and clinical intoxication. Animal exposure to mycotoxins reflects diet composition with major differences occurring between animals kept predominantly of pastures, i.e. ruminants and horses, and those consuming formulated feed like pigs and poultry. Mixed feeds are composed of several ingredients, often sourced from different continents. Subsequently, practitioners may confront endemic diseases and signs of toxin exposure related to toxins imported accidentally with contaminated feed materials from other countries and continents. Mycotoxins comprise more than 300 to 400 different chemicals causing a variety of clinical symptoms. Mycotoxin exposure causes major economic losses due to reduced performance, impaired feed conversion and fertility, and increased susceptibility to environmental stress and infectious diseases. In acute cases, clinical symptoms following mycotoxin ingestion are often non-specific, hindering an immediate diagnosis. Furthermore, most mold species produce more than one toxin, and feed commodities are regularly contaminated with various mold species resulting in complex mixtures of toxins in formulated feeds. The effects of these different toxins may be additive, depending on the level and time of exposure, and the intensity of the clinical symptoms based on age, health, and nutritional status of the exposed animal(s). Threshold levels of toxicity are difficult to define and discrepancies between analytical data and clinical symptoms are common in daily practice. This review aims to provide an overview of Aspergillus and Penicillium toxins that are frequently found in feed commodities and discusses their effects on animal health and productivity.

Impact of Corn Earworm (Lepidoptera: Noctuidae) on Field Corn (Poales: Poaceae) Yield and Grain Quality

Corn earworm, Helicoverpa zea (Boddie), commonly infests field corn, Zea mays (L.). The combination of corn plant biology, corn earworm behavior in corn ecosystems, and field corn value renders corn earworm management with foliar insecticides noneconomical. Corn technologies containing Bacillus thuringiensis (Bt) Berliner (Bacillales: Bacillaceae) were introduced that exhibit substantial efficacy against corn earworm and may reduce mycotoxin contamination in grain. The first generation Bt traits in field corn demonstrated limited activity on corn earworm feeding on grain. The pyramided corn technologies have greater cumulative protein concentrations and higher expression throughout the plant, so these corn traits should provide effective management of this pest. Additionally, reduced kernel injury may affect physical grain quality. Experiments were conducted during 2011-2012 to investigate corn earworm impact on field corn yield and grain quality. Treatments included field corn hybrids expressing the Herculex, YieldGard, and Genuity VT Triple Pro technologies. Supplemental insecticide treatments were applied every 1-2 d from silk emergence until silk senescence to create a range of injured kernels for each technology. No significant relationship between the number of corn earworm damaged kernels and yield was observed for any technology/hybrid. In these studies, corn earworm larvae did not cause enough damage to impact yield. Additionally, no consistent relationship between corn earworm damage and aflatoxin contamination was observed. Based on these data, the economic value of pyramided Bt corn traits to corn producers, in the southern United States, appears to be from management of other lepidopteran insect pests including European and southwestern corn borer.

Updated Overview of Infrared Spectroscopy Methods for Detecting Mycotoxins on Cereals (Corn, Wheat, and Barley)

Each year, mycotoxins cause economic losses of several billion US dollars worldwide. Consequently, methods must be developed, for producers and cereal manufacturers, to detect these toxins and to comply with regulations. Chromatographic reference methods are time consuming and costly. Thus, alternative methods such as infrared spectroscopy are being increasingly developed to provide simple, rapid, and nondestructive methods to detect mycotoxins. This article reviews research conducted over the last eight years into the use of near-infrared and mid-infrared spectroscopy to monitor mycotoxins in corn, wheat, and barley. More specifically, we focus on the Fusarium species and on the main fusariotoxins of deoxynivalenol, zearalenone, and fumonisin B1 and B2. Quantification models are insufficiently precise to satisfy the legal requirements. Sorting models with cutoff levels are the most promising applications.

Occurrence of Ochratoxin A in Infant Foods in the United States

Ochratoxin A (OTA) is a possible human carcinogen and occurs frequently in cereal grain, soy, and other agricultural commodities. Infants and young children may be more susceptible to contaminants than adults because of their lower body weight, higher metabolic rate, reduced ability to detoxify food toxicants, and more restricted diet. The purpose of this study was to investigate the occurrence and levels of OTA in infant formula and infant cereal products available in the U.S. market. In the present study, 98 powdered infant formula (milk- and soy-based) samples and 155 infant cereal (barley-, rice-, oat-, wheat-, and mixed grain-based) products were collected from different retail locations in the United States over a 2-year period. OTA levels were determined by liquid chromatography-tandem mass spectrometry. Although OTA was not detected in any of the infant formula samples, 47 (30%) of 155 infant cereals were contaminated with OTA in the range of 0.6 to 22.1 ng/g. At present, there is no regulatory limit for OTA in the United States. However, all of the positive samples were above the maximum level set by the European Commission (0.5 ng/g) for OTA in baby foods. OTA was detected in all types of infant cereals, but the highest incidence and concentrations were found in oat-based infant cereals (59%), followed by mixed grain cereals (34%). Increased surveillance and monitoring of OTA levels in grains used in infant foods may be needed to reduce exposure of infants and young children to OTA from cereal products.

Diversity of Fusarium species isolated from UK forage maize and the population structure of F. graminearum from maize and wheat

Pre-harvest contamination of forage maize by mycotoxin producing Fusarium species was investigated in the UK in 2011 and 2012. A total of 15 Fusarium species were identified from a collection of 1,761 Fusarium isolates recovered from maize stalks and kernels. This study characterized the diversity of Fusarium species present in forage maize in the UK. The predominant species detected were F. graminearum (32.9%) and F. culmorum (34.1%). Along with those species; F. avenacem, F. cerealis, F. equiseti, F. langsethiae, F. napiforme, F. oxysporum, F. poae, F. proliferatum, F. scripi, F. solani, F. subglutinans, F. tricinctum and, F. verticillioides were occasionally isolated. The trichothecene genotypes for F. graminearum were determined to be 84.9% deoxynivalenol (DON) and 15.0% nivalenol (NIV) while F. culmorum isolates were determined to have 24.9% DON and 75.1% NIV genotypes. A Bayesian model-based clustering method with nine variable number of tandem repeat markers was used to evaluate the population genetic structure of 277 F. graminearum isolates from the maize and wheat in the UK. There were three genetic clusters detected which were DON in maize, NIV in maize and DON in wheat. There were high admixture probabilities for 14.1% of the isolates in the populations. In conclusion, increased maize production in the UK and the high admixture rates in a significant portion of F. graminearum populations in maize and wheat will contribute to a new pathogen population which will further complicate breeding strategies for tolerance or resistance to this pathogen in both crops.

Nucleotide polymorphisms and protein structure changes in the Fg16 gene of Fusarium graminearum sensu stricto

Fusarium graminearum is one of the most important causes of wheat scab in different parts of the world. This fungus is able to produce widespread trichothecene mycotoxins such as nivalenol (NIV) and deoxynivalenol (DON) which are harmful for both human and animals. The Fg16 target is located in chromosome 1 of the F. graminearum genome coding for a hypothetical protein whose function is not yet known. The Fg16 gene is involved in lipid biosynthesis and leads to sexual development during colonization in wheat stalks. This gene is used to detect F. graminearum and determine the lineage of F. graminearum complex species. In the present study, polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) and DNA sequencing methods were employed in screening for genetic variation in 172 F. graminearum s.s. isolates. The PCR reaction forced the amplification of 410-bp fragments of Fg16. Two single nucleotide polymorphisms (T82C and A352T) and one amino acid exchange (C65S) with three patterns (TA/TA, CT/CT and TA/CT genotypes) were found in the Fg16 gene fragment. Two haplotypes, 1A and 1B, were identified within F. graminearum s.s. populations in northern and western regions of Iran. Two different secondary structures of protein were predicted for CT/CT and TA/CT genotypes of Fg16 gene. The average diversity levels detected were relatively high (He: 0.3238; Heu: 0.334; Ho: 0.2894; mean PIC: 0.514; mean Shannon's information index: 0.4132; mean number of alleles per locus: 1.473). On the basis of the obtained results, it was revealed that the Fg16 gene had a high degree of polymorphism that can be considered for future control programming strategies and thus the associations between the SSCP patterns with different traits of F. graminearum such as wheat colonization, perithecium formation on stalk tissues and lineage discrimination should be investigated.

Dietary ergot alkaloids as a possible cause of tail necrosis in rabbits

This study describes the association between tail necrosis in rabbits and mycotoxins in rabbit feed. Clinical cases of tail necrosis were observed in 14 out of 103 rabbits kept in an outdoor group housing, fed with hay and a commercial pelleted feed. The observed clinical symptoms, alopecia, erosions, crusts and necrosis were restricted to the tail area and exclusively occurred in young rabbits aged 113 ± 20 days. Dermatological examination suggested that ischemia had caused necrosis. Analysis of blood samples showed an elevated level of creatine kinase. No weight loss occurred in affected rabbits. Trauma caused by injuries or technopathic lesions was also excluded. Histopathologically, the lesions were characterized by acute muscle fibre degeneration and chronic active dermatitis with granulation tissue formation. Necropsy of one rabbit revealed hepatocellular degeneration and necrosis as remarkable findings. Feed analysis for ergot alkaloids by enzyme immunoassays yielded a mean and maximum ergot alkaloid content of 410 ± 250 μg/kg and 1,700 μg/kg, respectively. Faeces of affected rabbits contained ergot alkaloids at levels up to 200 μg/kg. The mean and maximum dietary intake of total ergot alkaloids were 17 and 71 μg/kg bodyweight, respectively. Fusarium toxins (trichothecenes, zearalenone, fumonisins) were also found in the feed, but at levels which did not explain the observed effects. The results indicate that ergot alkaloids may have been the cause of tail necrosis, which is supported by literature data showing that rabbits are especially sensitive towards these toxins.

Near- and mid-infrared spectroscopy as efficient tools for detection of fungal and mycotoxin contamination in agricultural commodities

In the last decade, near-infrared (NIR) and mid-infrared (MIR) spectroscopy have proven to be most promising tools for the detection of fungal contamination and estimation of mycotoxins in agricultural commodities, particularly of cereals. Owing to significant economic losses incurred from fungal contamination of foodstuffs, producers and processors are looking for fast, reliable, and less-expensive methods for the detection of fungal damage. In this context, NIR and MIR spectroscopy offer a fast, less-expensive, non-destructive, and relatively simple analytical method. Results from published studies indicate that NIR and MIR spectroscopy can be successfully applied to identifying fungal contamination and estimating specific mycotoxins. This review will focus on the applications of NIR and MIR spectroscopy to the classification of fungal contamination and the determination of specific mycotoxin contamination levels, and to compare this technology with traditional analytical methods.

Occurrence and within field variability of Fusarium mycotoxins and their masked forms in maize crops in Belgium

Maize ear rot caused by several Fusarium species is an important fungal disease. Apart from yield losses, ear rot fungi can produce mycotoxins and masked forms in infected grains. Masked mycotoxins have received increased attention in view of their bioavailability and potential toxicity in animals and humans, but their presence and relevance in the field still remain undisclosed. To get a better insight, the present study assessed the presence of various Fusarium parent and masked mycotoxins, i.e. deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, deoxynivalenol-3-glucoside, zearalenone, α-zearalenol, β-zearalenol, zearalenone-14-glucoside, zearalenone-14-sulfate, α-zearalenol-14-glucoside, β-zearalenol-14-glucoside, T-2 and HT-2 toxin, in various commercial maize varieties grown under natural infection conditions in Flanders, Belgium. The results showed that the maize varieties were co-contaminated with both parent and masked mycotoxins. Moreover, a positive correlation between these forms was established. A higher contamination with a particular mycotoxin appeared to be coupled with an elevated load of another (masked) mycotoxin. The results highlight the importance to screen for multiple mycotoxins, both parent and masked, to guarantee food and feed safety. Furthermore, analysis was carried out to elucidate the distribution of the various mycotoxins in the field. The maize variety did not significantly influence mycotoxin accumulation, except for deoxynivalenol. Subdivisions in the field with higher mycotoxin levels for deoxynivalenol and its derivatives, zearalenone and its derivatives, and the sum of T-2 and HT-2 toxin were observed.

Conjugation of deoxynivalenol by Alternaria alternata (54028 NRRL), Rhizopus microsporus var. rhizopodiformis (54029 NRRL) and Aspergillus oryzae (5509 NRRL)

Deoxynivalenol (DON, vomitoxin) is a trichothecene mycotoxin which can be considered to be an indicator of Fusarium mycotoxin contamination in grain, feed and food. Recent studies have described the presence of glucose conjugated DON, which is a product of plant metabolism, but there is a lack of information available on DON conjugation by fungi. The aim of the current study was, therefore, to investigate the ability of fungi to metabolize DON into hydrolysable conjugated DON. Alternaria alternata (54028 NRRL) and Rhizopus microsporus var. rhizopodiformis (54029 NRRL) were found to be capable of metabolizing DON into hydrolysable conjugated DON. This ranged from 13-23 % conjugation of DON in potato dextrose agar media and from 11-36 % in corn-based media. There was, however, considerable variation between fungal strains in the ability to conjugate DON as only a slight increase in hydrolysable conjugated DON (1-6 %) was observed when incubating with A. oryzae (5509 NRRL). A. oryzae (5509 NRRL) was also shown to degrade DON (up to 92 %) over 21 days of incubation on corn-based media. The current study shows that conjugation of DON can be achieved through fungal metabolism in addition to being a product of plant metabolism.

Adsorption of mycotoxins

In vitro binding studies with different mycotoxins are often made to test various adsorbents for their ability to detoxify these toxins in animal feed. In this study different clays were investigated for their ability to bind aflatoxin B1, zearalenone, ochratoxin A and deoxynivalenol in two different buffer systems (pH 3 and pH 6.5). In addition chemical/physical properties like cation exchange capacity and the concentration of exchangeable Ca(2+), Na(+), Mg(2+) and K(+) ions in the adsorbents were determined to establish if there is a connection between these parameters and the capacity to bind mycotoxins. Most of the tested clays showed high adsorption rates for aflatoxin B1 in both buffer systems. Adsorption rates for ochratoxin A and zearalenone of the tested clays were in the range of 0-100%. None of the tested adsorbents had the ability to bind deoxynivalenol. In this study no correlation between the cation exchange capacity of the clays or the concentration of exchangeable Ca(2+), Na(+), Mg(2+) and K(+) ions and the ability to adsorb mycotoxins could be investigated.

A survey of free and conjugated deoxynivalenol in the 2009, 2010 and 2011 cereal crops in Australia

Free and conjugated deoxynivalenol (DON, vomitoxin) were determined in samples of cereal grain collected from the 2009, 2010 and 2011 crops in the Australian states of New South Wales, Queensland, South Australia, Victoria and Western Australia. Free DON was absent in 53–64% of analysed samples. Levels of free DON ranged from 0.10 to 7.31 µg/g. The highest levels of free DON were found in samples collected from the New South Wales 2010 crop while no samples from South Australia or Western Australia regions contained this compound. Free DON in the samples collected from the 2010 crop was significantly higher compared with those from the 2009 and the 2011 crop. Conjugated DON was detected in 61, 87 and 68% of contaminated grain samples in the 2009, 2010 and 2011 crop, respectively. Conjugated DON was found mainly in the samples collected from the 2009 crop (up to 48%) and the 2011 crop (up to 43%) but no significant difference between free DON and total DON content was observed. The current survey emphasises the frequency of non-detectable, conjugated DON in Australian cereal crops and the potential challenges in understanding the hazard posed by DON-contaminated feedstuffs.

A survey of free and conjugated deoxynivalenol in the 2008 corn crop in Ontario, Canada

BACKGROUND

Deoxynivalenol (DON, vomitoxin), one of the most important mycotoxins produced by many Fusarium species, is found as a common contaminant of crops worldwide. Recent studies have described the presence of conjugated forms of DON (glycosides and fatty acid). The aim of the current study was therefore to investigate the natural occurrence of free and conjugated DON in Canadian corn.

RESULTS

Free and conjugated DON was determined by gas chromatography-mass spectrometry (GC-MS) and enzyme-linked immunosorbent assay (ELISA) in 86 corn samples collected from the 2008 crop in Ontario, Canada. Free DON concentrations determined by ELISA were similar to values determined in most samples using GC-MS. Conjugated DON was detected in 72 samples. Levels of free DON ranged from 0.17 to 14.00 µg g(-1) using GC-MS. The highest levels of free DON were found in corn samples from the southern and southwestern regions of Ontario, while samples from eastern regions were less contaminated. Conjugated DON was found mainly in corn from the east-central region, with five of six samples showing high levels of conjugated DON (up to 43% increase in DON following acid hydrolysis). Low levels of conjugated DON (≤ 10% increase in DON following acid hydrolysis) were detected in the majority of corn samples from the southwestern region (nine of 19 samples) and from the central region (16 of 36 samples).

CONCLUSION

The current survey emphasizes the frequency of conjugated DON in Ontario grown corn and the potential challenges in understanding the hazard posed by DON-contaminated foodstuffs and feedstuffs.

Difference in TRI13 gene sequences between the 3-acetyldeoxynivalenol producing Fusarium graminearum chemotypes from Canada and China

Positive-negative PCR assays based on the genes involved in the trichothecene biosynthesis pathway are useful in assessing the risk of trichothecene contamination in grain and are important in epidemiological studies. A single PCR detection method based on the structural gene sequence of TRI13 gene has been developed to predict the 3-ADON, 15-ADON and NIV chemotypes in China. The chemotypic differences are based on the deletions within the TRI13 gene. The objective of this study was to assess the reliability of using this single primer based on the TRI13 gene to differentiate the F. graminearum chemotypes in Canada. In this study, we found that, this single PCR detection method based on the deletions in the TRI13 gene cannot be used to differentiate the 3-ADON and 15-ADON chemotypes in the Canadian F. graminearum isolates; further sequence analysis of the PCR products confirmed that both Canadian 3-ADON and 15-ADON chemotypes have the 61 bp deletion in the TRI13 gene. This 61 bp deletion was absent in the Chinese 3-ADON isolates. Therefore these findings revealed that there are genetic differences between the examined 3-ADON F. graminearum isolates from Canada and China. The observed genetic differences between the 3-ADON chemotype populations in Canada and China may be resulted from a random mutation (insertion/deletion) that took place in one of the populations and accumulated due to genetic drift and/or selection.

Occurrence of zearalenone in wheat kernels infected with Fusarium culmorum

The aim of this study was to investigate the distribution of zearalenone in wheat kernels contaminated with this mycotoxin. Kernels from a sample of a wheat harvest affected by Fusarium culmorum were sorted into six groups according to their visual attributes. Milled portions of these groups were analysed by high-performance liquid chromatography with fluorescence and diode array detection. The clean-up was performed with an immunoaffinity column after methanol/water (4:1, v/v) extraction. The zearalenone content of the unsorted kernel fraction was 74 µg/kg. The group of healthy-looking kernels was contaminated with only 6 µg/kg of zearalenone. The groups of kernels that appeared shrunken and chalky white, damage routinely caused by Fusarium, were contaminated with 170 and 117 µg/kg, respectively. A remarkably high level of zearalenone contamination, 2,184 µg/kg, was observed for the group of reddish kernels. An association between the presence of the red pigment aurofusarin and high levels of zearalenone was found. Therefore, this pigment may be used as a marker of high zearalenone content.

A USA-Africa collaborative strategy for identifying, characterizing, and developing maize germplasm with resistance to aflatoxin contamination

Aflatoxin contamination of maize by Aspergillus flavus poses serious potential economic losses in the US and health hazards to humans, particularly in West Africa. The Southern Regional Research Center of the United States Department of Agriculture, Agricultural Research Service (USDA-ARS-SRRC) and the International Institute of Tropical Agriculture (IITA) initiated a collaborative breeding project to develop maize germplasm with resistance to aflatoxin accumulation. Resistant genotypes from the US and selected inbred lines from IITA were used to generate backcrosses with 75% US germplasm and F(1) crosses with 50% IITA and 50% US germplasm. A total of 65 S(4) lines were developed from the backcross populations and 144 S(4) lines were derived from the F(1) crosses. These lines were separated into groups and screened in SRRC laboratory using a kernel-screening assay. Significant differences in aflatoxin production were detected among the lines within each group. Several promising S(4) lines with aflatoxin values significantly lower than their respective US resistant recurrent parent or their elite tropical inbred parent were selected for resistance-confirmation tests. We found pairs of S(4) lines with 75-94% common genetic backgrounds differing significantly in aflatoxin accumulation. These pairs of lines are currently being used for proteome analysis to identify resistance-associated proteins and the corresponding genes underlying resistance to aflatoxin accumulation. Following confirmation tests in the laboratory, lines with consistently low aflatoxin levels will be inoculated with A. flavus in the field in Nigeria to identify lines resistant to strains specific to both US and West Africa. Maize inbred lines with desirable agronomic traits and low levels of aflatoxin in the field would be released as sources of genes for resistance to aflatoxin production.

Kinetics of adsorption and desorption of aflatoxin B1 by viable and nonviable bacteria

The reactions involved in the binding (adsorption) and release (desorption) of aflatoxin B1 (AFB1) to and from the surface of bacteria were investigated. Viable and heat-killed Lactobacillus rhamnosus GG, L. rhamnosus LC-705, and Propionibacterium freudenreichii subsp. shermanii JS were incubated in phosphate-buffered saline containing variable concentrations (0.0017 to 13.3 microg/ml) of AFB1. The relationship between the bacterial surface hydrophobicity and the AFB1 adsorption affinity was also investigated. A linear relationship was observed between the specific rate of AFB1 adsorption and the AFB1 concentration for all bacteria. The nature of desorption of adsorbed AFB1 was investigated by repetitive aqueous washes. A linear relationship was observed between the natural log value of the concentration of AFB1 adsorbed and the number of washes for all bacteria studied. The desorption constants were strain-dependent and were lower for heat-killed bacteria than for viable bacteria. Heat treatment appears to alter the surface properties of the bacteria rather than expose new adsorption sites. No correlation was found between the hydrophobicity and the AFB1 adsorption affinity.

Dietary strategies to counteract the effects of mycotoxins: a review

We reviewed various dietary strategies to contain the toxic effects of mycotoxins using antioxidant compounds (selenium, vitamins, provitamins), food components (phenolic compounds, coumarin, chlorophyll and its derivatives, fructose, aspartame), medicinal herbs and plant extracts, and mineral and biological binding agents (hydrated sodium calcium aluminosilicate, bentonites, zeolites, activated carbons, bacteria, and yeast). Available data are primarily from in vitro studies and mainly focus on aflatoxin B1, whereas much less information is available about other mycotoxins. Compounds with antioxidant properties are potentially very efficacious because of their ability to act as superoxide anion scavengers. Interesting results have been obtained by food components contained in coffee, strawberries, tea, pepper, grapes, turmeric, Fava tonka, garlic, cabbage, and onions. Additionally, some medicinal herbs and plant extracts could potentially provide protection against aflatoxin B1 and fumonisin B1. Activated carbons, hydrated sodium calcium aluminosilicate, and bacteria seem to effectively act as binders. We conclude that dietary strategies are the most promising approach to the problem, considering their limited or nil interference in the food production process. Nevertheless, a great research effort is necessary to verify the in vivo detoxification ability of the purposed agents, their mode of action, possible long-term drawbacks of these detoxification-decontamination procedures, and their economical and technical feasibility.

Mycotoxins: their implications for human and animal health

Mycotoxins contaminate various feed and food commodities, due to the global occurrence of toxinogenic molds. They exert adverse health effects in human and animals. The nature of these toxic effects varies depending on the chemical structure of the toxin. The degree of these adverse effects is not only determined by the toxin concentration present in foods and feeds, but also by the time of exposure. Whilst in animals, next to acute intoxication, losses in productivity, reduced weight gain and immunosuppression are considered as most important feature of mycotoxicoses, genotoxic effects and the involvement of certain mycotoxins such as aflatoxin, ochratoxins and fumonisins in the etiology of human cancers have obtained particular attention. This implies that recent research activities concentrate on mechanistic aspects of mycotoxin-induced pathologies, rather than compiling analytical measures of mycotoxin concentrations in food and feeds.

Biological detoxification of fungal toxins and its use in plant breeding, feed and food production

Enzymatic inactivation of fungal toxins is an attractive strategy for the decontamination of agricultural commodities and for the protection of crops from phytotoxic effects of fungal metabolites. This review summarizes research on the biological detoxification of fungal toxins by microorganisms and plants and its practical applications. Some mycotoxins are detoxified during ensiling and other fermentation processes (aflatoxins, alternariol, mycophenolic acid, patulin, PR toxin) while others are transformed into toxic products or survive fermentation unchanged. Plants can detoxify fomannoxin, fusaric acid, HC-toxin, ochratoxin A and oxalate but the degradation of deoxynivalenol has yet to be proven. Microflora of the digestive tract of vertebrates and invertebrates exhibit detoxification activities towards aflatoxins, ochratoxin A, oxalate and trichothecenes. Some toxin-producing fungi are able to degrade or transform their own products under suitable conditions. Pure cultures of bacteria and fungi which detoxify mycotoxins have been isolated from complex microbial populations by screening and enrichment culture techniques. Genes responsible for some of the detoxification activities have been cloned and expressed in heterologous hosts. The detoxification of aflatoxins, cercosporin, fumonisins, fusaric acid, ochratoxin A, oxalic acid, patulin, trichothecenes and zearalenone by pure cultures is reviewed. Finally, current application of these results in food and feed production and plant breeding is summarized and expected future developments are outlined.