Mycotoxin detection on antibody-immobilized conducting polymer-supported electrochemically polymerized acacia gum

Electrochemical polymerization of acacia gum (AG) was initiated by electroactive polyaniline (PANI) monomers by radical cation formation and their coupling reactions with AG molecules. R_CT values obtained from electrochemical impedance spectroscopy analysis at various AG concentrations with PANI were drastically decreased, confirming formation of conducting AG complexes with PANI. Quantitative analysis of ochratoxin-A (OTA) detection in electrolyte was carried out on rabbit antibody-immobilized PANI and PANI–AG matrices. The observed sensitivities of 50, 150, and 250 mg AG-added PANI matrix-based platforms were 3.3 ± 0.5, 10.0 ± 0.5, and 12.7 ± 0.5 μA/ng/ml, respectively. The sensitivity of only PANI electrodes was 2.6 ± 0.3 μA/ng/ml, which was relatively lower than AG-added PANI. This increase was due to the presence of glycan functional groups in AG molecules that supported the retention of activity of antibodies. In addition, enhanced electron transportation at AG–PANI film surface was observed due to formation of an electroactive polymer film of two different electroactive functions to contribute toward enhancement in the detection sensitivity.     

Mycotoxin contamination of food in Europe: Early detection and prevention strategies

This paper reviews the early detection and prevention strategies which have been employed in Europe for the control of mycotoxin contamination of food in the context of a hazard analysis critical control point (HACCP) framework. The critical control points (CCPs) in the whole food chain where mycotoxins such as trichothecenes and ochratoxins are important have been identified. Ecological studies on the effect of environmental factors which are marginal for growth and mycotoxin production have been identified for Fusarium culmorum and F. graminearum (deoxynivlenol production), and for Penicillium verrucosum and Aspergillus ochraceus (ochratoxin production) in relation to cereal production and for A. carbonarius in relation to grapes and wine production (ochratoxin formation). To minimise the entry of these mycotoxins into the food chain, effective and rapid diagnostic tools are required to monitor the CCPs effectively. To this end the potential use of molecular imprinted polymers, lateral flow devices and molecular-based techniques for the rapid detection and quantification of the mycotoxigenic moulds or their toxins have also been developed.     

Mycotoxin producing fungi

Mycotoxins are relatively small molecules characterized by a diversity of chemical structure and a diversity of biological activity. They are often genotypically specific for a group of species, but the same compound can also be formed by fungi belonging to different genera. Most of the mycotoxins known have been recognized as metabolic products of Aspergillus, Penicillium and Fusarium species. This review will be focused on aflatoxins, ochratoxins and fumonisins because of their hazard to animal and human health. The production of these mycotoxins have been usually associated with a small number of species but some recent studies have reported the production of these mycotoxins by some other species. These results show that mycotoxin production is broader than is normally thought, so the possibility can not be ruled out that new species may be a new source of unexpected mycotoxins in their natural substrates.     

Mycotoxin research in humans

This study investigates the occurrence of aflatoxins in Ecuador. Early investigators proved the presence of aflatoxins in human and animal food, but the disturbing data lead to the formation of two research teams at Guayaquil University and the Agrarian University of Ecuador to investigate aflaxotins and other mycotoxins in food and their relationship to human health. Because the concept of mycotoxicosis as a result of the secondary metabolites produced by different species of moulds could cause different clinical patterns, the research team includes Aspergillus metabolites found in the urine of a patient with pulmonary aspergilloma. We considered that the body itself could create secondary metabolites. An ELISA method was used to detect mycotoxins with the specific reactive compounds using a company base assay. This allows the detection quantitative of such metabolites in 24 h collected urine. The patient was treated with itraconazole for nine months, after clinical, radiological and aflatoxins testing. We also investigated three other cases in children with a second level of malnutrition and only with vomitoxins results and in three investigated cases of otomycosis caused by Aspergillus niger only in one case traces of aflatoxins were found.     

Tremorgenic Mycotoxin from Penicillium paraherquei

A tremorgenic mycotoxin was isolated from Penicillium paraherquei Abe ex G. Smith and identified as verruculogen. It was produced at the rate of approximately 1 mg/g of the dried fungal mycelium cultured on peptone-enriched Czapek-Dox medium at 28°C.     

Mycotoxin production by indoor molds

Fungal growth in buildings starts at a water activity (a(w)) near 0.8, but significant quantities of mycotoxins are not produced unless a(w) reaches 0.95. Stachybotrys generates particularly high quantities of many chemically distinct metabolites in water-damaged buildings. These metabolites are carried by spores, and can be detected in air samples at high spore concentrations. Very little attention has been paid to major metabolites of Stachybotrys called spirocyclic drimanes, and the precise structures of the most abundant of these compounds are unknown. Species of Aspergillus and Penicillium prevalent in the indoor environment produce relatively low concentrations of mycotoxins, with the exception of sterigmatocystins that can represent up to 1% of the biomass of A. versicolor at a(w)'s close to 1. The worst-case scenario for homeowners is produced by consecutive episodes of water damage that promote fungal growth and mycotoxin synthesis, followed by drier conditions that facilitate the liberation of spores and hyphal fragments.     

Mycotoxin production by some IndianAlternaria species

A total of seven species ofAlternaria: A. alternata (Fr.) Keissler;A. capsici-annui Savul & Sandu;A. citri Ellis & Pierce;A. porri (Ellis) Clfferi;A. radicina Meler, Drechsler & Eddy;A. tenuissima (Kunze: Pers) Wiltshire andA. tomato (Cooke) Jones were screened on rice culture medium for their ability to elaborate five majorAlternaria mycotoxins viz. tenuazonlc acid (TA), alternariol (AOH), alternariol methyl ether (AME), altenuene (ALT) and altertoxin-l (ATX-I). All the species produced mycotoxins in varying concentrations. A.capsici-annul was recorded as the mycotoxin producer for the first time. ALT byA. citri andA. tomato; ALT, and ATX-I byA. tenuissima; ALT, TA and AME byA. porri and TA byA. radicina are the new additions to the list of mycotoxins produced by the respective species ofAlternaria.     

Mycotoxin production from fungi isolated from grapes

AIMS: In order to assess the potential for producing mycotoxins, fungi were isolated from wine producing grapes. METHODS AND RESULTS: The isolates were identified and Penicillium expansum, the most well recognized mycotoxin producer, was analysed for mycotoxin production by TLC. Many of the strains produced patulin and/or citrinin, often depending on whether they were grown on a grape or yeast extract sucrose media. CONCLUSION: Citrinin was produced by all strains grown in the yeast extract sucrose medium, but only one strain (from 51) was able to produce this compound in grape juice medium. Patulin was produced in the yeast extract medium by 20 strains and in grape juice medium by 33 strains. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of mycotoxins in wine producing grapes is discussed. Grapes contamination with patulin seems not to contribute to wine contamination, and no ochratoxin producing fungi was identified.     

Mycotoxin from a Blue-Eye Mold of Corn

High-moisture yellow dent corn became heavily molded by Penicillium martensii after storage for 6 months at 1 C. Mice ingesting corn molded by P. martensii died within a few days. The toxin was isolated and identified as penicillic acid. Large quantities of the toxin accumulated over a 3-month period on artificially inoculated corn incubated at temperatures between 1 and 15 C. At higher temperatures, the toxin disappeared within 45 days.     

Mycotoxin risks are lower in biotech corn

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Mycotoxin production by some wood-associated Penicillium spp.

Twenty-five strains of Penicillium spp. isolated from mould-infected discoloured outdoor softwood were analysed for mycotoxin production. Patulin was found to be produced by Penicillium expansion at 4° and 20°C incubation when cultured on wood blocks and wood chips. One strain of P. nordicum (not wood-associated) produced ochratoxin A when cultured on wood chips.     

Mycotoxin Production by Fusarium Species Isolated from Bananas

The ability of Fusarium species isolated from bananas to produce mycotoxins was studied with 66 isolates of the following species: F. semitectum var. majus (8 isolates), F. camptoceras (3 isolates), a Fusarium sp. (3 isolates), F. moniliforme (16 isolates), F. proliferatum (9 isolates), F. subglutinans (3 isolates), F. solani (3 isolates), F. oxysporum (5 isolates), F. graminearum (7 isolates), F. dimerum (3 isolates), F. acuminatum (3 isolates), and F. equiseti (3 isolates). All isolates were cultured on autoclaved corn grains. Their toxicity to Artemia salina L. larvae was examined. Some of the toxic effects observed arose from the production of known mycotoxins that were determined by thin-layer chromatography, gas chromatography, or high-performance liquid chromatography. All F. camptoceras and Fusarium sp. isolates proved toxic to A. salina larvae; however, no specific toxic metabolites could be identified. This was also the case with eight isolates of F. moniliforme and three of F. proliferatum. The following mycotoxins were encountered in the corn culture extracts: fumonisin B(inf1) (40 to 2,900 (mu)g/g), fumonisin B(inf2) (150 to 320 (mu)g/g), moniliformin (10 to 1,670 (mu)g/g), zearalenone (5 to 470 (mu)g/g), (alpha)-zearalenol (5 to 10 (mu)g/g), deoxynivalenol (8 to 35 (mu)g/g), 3-acetyldeoxynivalenol (5 to 10 (mu)g/g), neosolaniol (50 to 180 (mu)g/g), and T-2 tetraol (5 to 15 (mu)g/g). Based on the results, additional compounds produced by the fungal isolates may play prominent roles in the toxic effects on larvae observed. This is the first reported study on the mycotoxin-producing abilities of Fusarium species that contaminate bananas.     

Mycotoxin formation in moist wheat under controlled temperatures

One-kilogram parcels of wheat with 20.5% moisture content were maintained at 15° and 22 °C for 10 weeks to study quality changes. Temperature, moisture, oxygen and carbon dioxide levels, microfloral incidence and abundance, seed germination, fat acidity values, aflatoxins, sterigmatocystin, ochratoxin A, penicillic acid, citrinin and zearalenone were monitored. By two weeks, trace levels of ochratoxin had formed at both temperatures. By 10 weeks, the wheat contained at least three times more ochratoxin A at 22 °C than at 15 °C. Strains of Penicillium verrucosum var. cyclopium were associated with ochratoxin A production. No other mycotoxins were detected. The effect of temperature was significant for all variables (greater effect at 22 °C) except A. glaucus gr. and Penicillium (P<.01). The effect of time was significant for all variables except bacteria (P<.01). The shape of the response was fully characterized by the linear and quadratic terms, except for % moisture which was linear only, and for bacteria for which time was not significant. The interaction between time and temperature was significant (P<.01) for total fungal propagule count, % moisture, and Aspergillus versicolor, indicative of the steeper rise in slope for 22 °C.