Further mycotoxin effects from climate change
Climate change will affect mycotoxins in food. The 2007 Intergovernmental Panel on Climate Change report is reinterpreted herein to account for what may occur with mycotoxins. Warmer weather; heat waves; greater precipitation and drought will have various impacts; depending on which regions of the world and mycotoxin systems are considered. The humidity issues are more complex as some areas will experience drought and others greater precipitation: in vivo data on the effects of moisture on mycotoxins in crops are more ambiguous than those for temperature. In vitro data on fungal growth and mycotoxin production may not relate directly to the situation in the field or post harvest; but are useful for base-line assumptions. The effects of climate in various regions of the world; i.e. Africa; Europe; Asia; Latin America and North America are considered in terms of mycotoxin contamination. Crops introduced to exploit altered climate may be subject to fewer mycotoxin producing fungi (the ÂParasites Lost phenomenon). Increased mycotoxins and UV radiation may cause fungi to mutate on crops and produce different mycotoxins. Whereas there is relevant information on aflatoxins; deoxynivalenol; and ochratoxin A; more mycotoxins require to be considered:Data on patulin are missing. The current paper considers uniquely ergot alkaloids. Amelioration strategies are provided. There is considerable urgency in the need to address these issues.
Aflatoxin B1 Degradation by Bacillus subtilis UTBSP1 isolated from pistachio nuts of Iran
Pistachio nuts are among the commodities with the highest risk of aflatoxin contamination in Iran. Aflatoxin B1 (AFB1) is one of the most hazardous mycotoxins for humans and livestock. In nature; there are microorganisms which are capable of reducing aflatoxins contamination in food and feed products. In this study; Bacillus subtilis strain UTBSP1 was isolated from pistachio nuts and studied for the degradation of AFB1. The AFB1 contents were determined by the use of HPTLC and HPLC as well as multiple reactions monitoring (MRM) method in LC-MS/MS. The results indicated B. subtilis UTBSP1 could considerably remediate AFB1 from nutrient broth culture and pistachio nut by 85.66% and 95%; respectively. Cell free supernatant fluid caused an apparent 78.39% decrease in AFB1 content. The optimal conditions for AFB1 degradation by cell free supernatant appeared at 35-40°C; during 24 h. Furthermore; the results indicated that AFB1 degradation is enzymatic and responsible enzymes are extracellular and constitutively produced. Besides; B. subtilis UTBSP1-treatment of AFB1 contaminated pistachio nuts; resulted in 95% degradation of AFB1 after 5 days. Highlights: We find the beneficial strain of Bacillus subtilis in Iranian pistachio nut. It causes the reducing of AFB1content in liquid culture and pistachio nut. It destructs AFB1 by the extracellular constitutively produced enzyme. The destructive AFB1 differs from AFB1 chemically; and loses a fluorescence property.
Contamination of Cyclopiazonic Acid in Dried Figs and Co-occurrence of Aflatoxin
Natural cyclopiazonic acid (CPA) and aflatoxin (AF) contamination were investigated in Aspergillus section Flavi positive dried fig samples collected from orchards after harvesting. Cyclopiazonic acid and AF were determined by thin-layer chromatography (TLC) and high performance liquid chromatography (HPLC); respectively. Cyclopiazonic acid was found in all samples of dried figs that contain AF. Cyclopiazonic acid and AF co-occurred in 23% of the samples. The number of dried fig samples contaminated with CPA was higher than the samples containing AF. Therefore CPA was a more common mycotoxin than AF in dried figs. To the best of our knowledge; this is the first report of CPA and co-occurrence of CPA and AF in dried figs. Higlights: Cyclopiazonic acid and AF co-occurred in 23% of the Aspergillus section Flavi positive dried fig samples. The number of dried fig samples contaminated with CPA was higher than the samples containing AF. Therefore CPA was a more common mycotoxin than AF in dried figs. This is the first report of CPA and co-occurrence of CPA and AF in dried figs.
Immunomagnetic bead-based recovery and real time quantitative PCR (RT iq-PCR) for sensitive quantification of aflatoxin B
Aflatoxin B1 is an unavoidable natural mycotoxin that enters the food chain by contamination of food grains and feedstuffs; potentially posing carcinogenic risks to animal and human health. Immuno-PCR methods have the potential to address the need of meeting the regulatory limits by detecting trace levels of toxins present in food and animal feeds. This paper describes a real-time immuno-quantitative PCR (RT-iqPCR) assay for quantification of aflatoxin B1 suspended in methanol:water solution that can also serve as an extraction solvent. Immuno-PCR approaches were examined including direct vs. indirect sandwich assays using monoclonal vs. polyclonal antibodies. Our best approach was obtained using monoclonal antibodies to capture aflatoxin in solution prior to immobilizing the Fc portion of the capture antibodies onto to protein G magnetic beads. This was followed by the addition of a polyclonal Âsignal antibody tethered with an oligonucleotide template for a subsequent PCR assay. The RT-iqPCR assay described herein lead to the sensitive detection and quantification of aflatoxin B1 from 10 ppb down to 0.1 ppb with high correlation (r2 = 0.97) and efficiency (99.5%). The approach also detected the high-dose Âhook effect phenomenon (excess antigen) which was overcome by the use of dilution protocols to eliminate false negatives that may occur at levels above quantification limits. The RT-iqPCR approach discussed here is presented as a model system that could easily be adapted for aflatoxin detection in a variety of food or animal feed samples using a simple methanol:water solution as an extraction solvent.
A high selective immunochromatographic assay for rapid detection of aflatoxin B
To solve the problem of low selectivity of current immunochromatographic assay (ICA) for aflatoxin B1 (AFB1) alone detection; a novel selective ICA was developed here. With very high selectivity; a new AFB1 monoclonal antibody (MAb) 3G1 was preparaed by immunizing Balb/c mice with aflatoxin B2a-BSA (AFB2a-BSA) rather than AFB1-BSA used in other reports and 3G1 possessed the highest selectivity than those used in published ICAs. The ICA with visual detection limit (VDL) of 1 ng mL-1 showed no cross-reactivity with other aflatoxins. Comparing with previous reports; the ICA here provided the most powerful guarantee for avoiding false positive results leaded by coexistence of other aflatoxins in samples. For validation; naturally contaminated samples including peanut; puer-tea; vegetable oil and feedstuff were respectively assayed by ICA and a standard high performance liquid chromatography (HPLC); and good agreement of results was obtained between two methods. Therefore; the developed ICA could well meet the selective detection of AFB1 in agro-products.
Key Roles of Vitamins A; C; and E in Aflatoxin B1-Induced Oxidative Stress.
Abstract: Aflatoxins (Aspergillus flavus toxins) are one of the natural toxic molecules which are produced by a group of fungi called Aspergillus. Foods and drinks contaminated with aflatoxins cause global health and environmental problems. Today in many developing countries; these toxins are leading cause of some liver cancers and serious gastrointestinal problems. Aflatoxins; which are well known to be mutagenic; carcinogenic; hepatotoxic; and immunosuppressive; exert inhibitory effects on biological processes including DNA synthesis; DNA-dependent RNA synthesis; DNA repair; and protein synthesis. Aflatoxins B1 (AFB1) is the most widespread oxidative agent of the aflatoxins. Numerous diverse compounds and extracts have been reported to reduce the aflatoxins induced oxidative stress in the body. Most of these inhibitors including phenylpropanoids; terpenoids; alkaloids; and vitamins are originally derived from plants. Among these; being essential biomolecules; vitamins are used as coenzymes in very significant biological reactions. They also function as nonenzymatic antioxidative agents protecting the cells from oxidative stress-induced toxicity and transformation. This chapter reviews the mechanism of AFB1-induced oxidative stress and focuses on the protective effects of vitamins A; C; and E on reducing this stress.
Detection of contaminated hazelnuts and ground red chili pepper flakes by multispectral imaging
Mycotoxins are the toxic metabolites of certain filamentous fungi and have been demonstrated to cause various health problems in humans; including immunosuppression and cancer. Among them; the aflatoxins have received greater attention because they are potent carcinogens and are responsible for many human deaths per annum; mostly in non-industrialized countries. Various regulatory agencies have enforced limits on the concentrations of these toxins in foods and feeds involved in international commerce. Hyperspectral and multispectral imaging are becoming increasingly important for rapid and nondestructive testing for the presence of such contaminants. However; the high number of spectral bands needed may render such image acquisition systems too complex; expensive and slow. Moreover; they tend to generate overwhelming amount of data; making effective processing of this information in real time difficult. In this study; a two-dimensional local discriminant bases algorithm was developed to detect the location of the discriminative features in the multispectral data space. The algorithm identifies the optimal passband width and center frequencies of optical filters to be used for a multispectral imaging system. This was applied to a multispectral imaging system used to detect aflatoxin-contaminated hazelnut kernels and red chili peppers. Classification accuracies of 92.3% and 80% were achieved for aflatoxin-contaminated and uncontaminated hazelnuts and red chili peppers; respectively. The aflatoxin concentrations were decreased from 608 to 0.84 ppb for tested hazelnuts and from 38.26 to 22.85 ppb for red chili peppers by removal of the nuts/peppers that were classified as aflatoxin-contaminated. The algorithm was also used to classify fungal contaminated and uncontaminated hazelnut kernels; and an accuracy of 95.6% was achieved for this broader classification.
The influence of different nitrogen and carbon sources on mycotoxin production in Alternaria alternata
The aim of this study was to determine the influence of different carbon and nitrogen sources on the production of the mycotoxins alternariol (AOH); alternariol monomethyl ether (AME) and tenuazonic acid (TA) by Alternaria alternata at 28 °C using a semi-synthetic medium (modified Czapek-Dox broth) supplemented with nitrogen and carbon sources. Additionally the effect of shaken and static cultivation on mycotoxin production was tested. Initial experiments showed a clear dependency between nitrogen depletion and mycotoxin production. To assess whether nitrogen limitation in general or the type of nitrogen source triggers the production; various nitrogen sources including several ammonium/nitrate salts and amino acids were tested. In static culture the production of AOH/AME can be enhanced greatly with phenylalanine whereas some nitrogen sources seem to inhibit the AOH/AME production completely. TA was not significantly affected by the choice of nitrogen source. In shaken culture the overall production of all mycotoxins was lower compared to static cultivation. Furthermore tests with a wide variety of carbon sources including monosaccharides; disaccharides; complex saccharides such as starch as well as glycerol and acetate were performed. In shaken culture AOH was produced when glucose; fructose; sucrose; acetate or mixtures of glucose/sucrose and glucose/acetate were used as carbon sources. AME production was not detected. The use of sodium acetate resulted in the highest AOH production. In static culture AOH production was also stimulated by acetate and the amount is comparable to shaken conditions. Under static conditions production of AOH was lower except when cultivated with acetate. In static cultivation 9 of 14 tested carbon sources induced mycotoxin production compared to 4 in shaken culture. This is the first study which analyses the influence of carbon and nitrogen sources in a semi-synthetic medium and assesses the effects of culture conditions on mycotoxin production by Alternaria alternata.
Effect of anilinopyrimidine resistance on aflatoxin production and fitness parameters in Aspergillus parasiticus Speare
ABSTRACT: Mutants of Aspergillus parasiticus resistant to the anilinopyrimidine fungicides were isolated at a high mutation frequency after UV-mutagenesis and selection on media containing cyprodinil. In vitro fungitoxicity tests resulted in the identification of two predominant resistant phenotypes that were highly (R1-phenotype) and moderately (R2-phenotype) resistant to the anilinopyrimidines cyprodinil; pyrimethanil and mepanipyrim. Cross-resistance studies with fungicides from other chemical groups showed that the highly resistance mutation(s) did not affect the sensitivity of R1-mutant strains to fungicides affecting other cellular pathways. Contrary to that; a reduction in the sensitivity to the triazoles epoxiconazole and flusilazole; the benzimidazole carbendazim; the phenylpyrrole fludioxonil; the dicarboximide iprodione and to the strobilurin-type fungicide pyraclostrobin was observed in R2-mutant strains. Study of fitness parameters of anilinopyrimidine-resistant strains of both phenotypic classes showed that all R1 mutant strains had mycelial growth rate; sporulation and conidial germination similar to or even higher than the wild-type parent strain; while these fitness parameters were negatively affected in R2 mutant strains. Analysis of the aflatoxin production showed that most R1 mutant strains produced aflatoxins at concentrations markedly higher than the wild-type parent strain. A considerable reduction in the aflatoxin production was observed on cultured medium and on wheat grains by all R2 mutant strains; indicating a possible correlation between fitness penalties and aflatoxigenic ability of A. parasiticus. The potential risk of increased aflatoxin contamination of agricultural products and their byproducts by the appearance and predominance of highly aflatoxigenic mutant strains of A. parasiticus resistant to the anilinopyrimidines is discussed.
Evaluation of antimicrobial and physical properties of edible film based on carboxymethyl cellulose containing potassium sorbate on some mycotoxigenic Aspergillus species in fresh pistachios.
Active packaging is a relatively novel concept of packaging that changes the conditions of the packaged food to extend its shelf-life and improve its safety. In this study; antimicrobial effects of carboxymethyl cellulose based-edible film containing potassium sorbate as an antimicrobial agent were studied against Aspergillus flavus (PTCC-5004); Aspergillus parasiticus (PTCC-5286) and Aspergillus parasiticus (PTCC-5018) by using agar diffusion assay. Results showed suitable inhibition effects against Aspergillus parasiticus (PTCC-5286) and Aspergillus flavus (PTCC-5004) in comparison with Aspergillus parasiticus (PTCC-5018). Pistachios were coated with this edible antimicrobial film containing three concentrations of sorbate (1; 0.5 and 0.25 g/100 mL film solution); all concentrations showed no growth of molds. Tensile strength values of films with potassium sorbate; decreased when compared to control; and film's flexibility; was 28.82 percent for 3 g/100 mL sorbate; while higher concentration of sorbate; decreased the flexibility. The water vapor permeability values (WVP) of films were determined to be 1.18 (g mm/m2 day kPa) for films plasticized with glycerol; without sorbate while WVP values for the films containing 1 and 2 g/100 mL sorbate increased to 3.77 and 15.5 (g mm/m2 day kPa); respectively. The observed glass transition temperature (TG) depression for these polymer blends was related to the plasticizer content (water; polyethylene; and glycerol); especially water.