Special Issue "Advances in Mycotoxin Research"
Quicklinks
A special issue of Toxins (ISSN 2072-6651).
Deadline for manuscript submissions: closed (30 November 2009)
Special Issue Editors
Guest Editor
Dr. Jeffrey W. Cary
Molecular Biologist USDA, ARS, SRRC, 1100 Robert E. Lee Blvd., New Orleans, LA 70124-4305, USA
Website: http://www.ars.usda.gov/pandp/people/people.htm?personid=907
E-Mail: jeff.cary@ars.usda.gov
Phone: +1 504 286 4264
Fax: +1 504 286 4533
Interests: molecular biology of mycotoxin biosynthesis and regulation; fungal-host plant interactions; secondary metabolism; gene clusters; genomics; antifungal peptides; transgenic approaches to mycotoxin elimination in plants
Guest Editor
Dr. Ana Calvo
Northern Illinois University, Biological Sciences, 1425 W. Lincoln Hwy Montgomery Hall, Dekalb, IL 60115, USA
Website: http://www.bios.niu.edu/calvo/calvo.shtml
E-Mail: amcalvo@niu.edu
Special Issue Information
Dear Colleagues,
Fungi produce a diverse array of secondary metabolites some of which have desirable antibiotic properties while others are harmful toxins. Mycotoxins can have adverse impacts on the health of humans and other animals as well as negative economic impacts on agriculture and associated industries. It is estimated that almost a third of the world’s food supply is contaminated with mycotoxins. Developing countries are often without the resources to detect and monitor mycotoxins in their food supplies and are therefore the hardest hit both economically and health-wise due to the presence of mycotoxins in agricultural crops. This special issue of Toxins is devoted to recent advances in mycotoxin research with emphasis placed on the most agriculturally relevant fungi and the mycotoxins they produce. These include aflatoxins produced mainly by Aspergillus flavus and A. parasiticus, trichothecenes produced mainly by Fusarium graminearum, fumonisins produced by Fusarium verticillioides and ochratoxin produced mainly by Aspergillus ochraceus and Penicillium verrucosum. Topics of interest will include the genetics and biology of fungal toxin production, mycotoxin detection, plant breeding and transgenic technologies for resistance, biocontrol, ecology/evolution of mycotoxigenic fungi, medically important mycotoxigenic fungi, and mycotoxin risk management and regulatory issues.
Ana Calvo, Ph. D.
Jeffrey W. Cary, Ph. D.
Guest Editors
Submission
All papers should be submitted to toxins@mdpi.com with copy to the guest editor. To be published continuously until the deadline and papers will be listed together at the special websites.
Submitted papers should not have been previously published nor be currently under consideration for publication elsewhere. All papers are refereed through a peer review process. A guide for authors, sample copies and other relevant information for submitting papers are available on the Instructions for Authors page. Toxins is an international peer-reviewed monthly journal published by MDPI.
Article Processing Charges (APC) for publication in this open access journal are waived for well-prepared manuscripts submitted by 30 June 2010. English correction or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those paper accepted for publication, that require extensive additional formatting and/or English corrections.
Keywords
- Aspergillus
- Fusarium
- mycotoxins
- aflatoxins
- fumonisins
- trichothecenes
- ochratoxin
- secondary metabolites
- regulation
- detection
Published Papers (12 papers)
|
Received: 13 November 2009; in revised form: 20 November 2009 / Accepted: 7 December 2009 / Published: 8 December 2009
Show/Hide Abstract
| Download PDF Full-text (613 KB) | Download XML Full-text | 
Abstract: Dothistromin is a non-host selective toxin produced by the pine needle pathogen Dothistroma septosporum. Dothistromin is not required for pathogenicity, but may have a role in competition and niche protection. To determine how D. septosporum tolerates its own toxin, a putative dothistromin transporter, DotC, was investigated. Studies with mutants lacking a functional dotC gene, overproducing DotC, or with a DotC-GFP fusion gene, did not provide conclusive evidence of a role in dothistromin efflux. The mutants revealed a major effect of DotC on dothistromin biosynthesis but were resistant to exogenous dothistromin. Intracellular localization studies suggest that compartmentalization may be important for dothistromin tolerance.
|
|
Received: 9 October 2009; in revised form: 19 November 2009 / Accepted: 8 December 2009 / Published: 8 December 2009
Show/Hide Abstract
| Download PDF Full-text (104 KB) | Download XML Full-text
Abstract: Mycotoxin contamination in rice is less reported, compared to that in wheat or maize, however, some Fusarium fungi occasionally infect rice in the paddy field. Fumonisins are mycotoxins mainly produced by Fusarium verticillioides, which often ruins maize. Rice adherent fungus Gibberella fujikuroi is taxonomically near to F. verticillioides, and there are sporadic reports of fumonisin contamination in rice from Asia, Europe and the United States. Therefore, there exists the potential risk of fumonisin contamination in rice as well as the need for the validated analytical method for fumonisins in rice. Although both natural and spiked reference materials are available for some Fusarium mycotoxins in matrices of wheat and maize, there are no reference materials for Fusarium mycotoxins in rice. In this study, we have developed a method for the preparation of a reference material containing fumonisins in Thai rice. A ShakeMaster grinding machine was used for the preparation of a mixed material of blank Thai rice and F. verticillioides-infected Thai rice. The homogeneity of the mixed material was confirmed by one-way analysis of variance, which led this material to serve as an in-house reference material. Using this reference material, several procedures to extract fumonisins from Thai rice were compared. Accordingly, we proved the applicability of an effective extraction procedure for the determination of fumonisins in Japanese rice.
|
|
Received: 17 November 2009; in revised form: 4 December 2009 / Accepted: 9 December 2009 / Published: 10 December 2009
Show/Hide Abstract
| Download PDF Full-text (309 KB) | Download XML Full-text
Abstract: Immunoassays are routinely used in the screening of commodities and foods for fungal toxins (mycotoxins). Demands to increase speed and lower costs have lead to continued improvements in such assays. Because many reported mycotoxins are low molecular weight (below 1 kDa), immunoassays for their detection have generally been constructed in competitive heterogeneous formats. An exception is fluorescence polarization immunoassay (FPIA), a homogeneous format that does not require the separation of bound and free labels (tracer). The potential for rapid, solution phase, immunoassays has been realized in the development of FPIA for many of the major groups of mycotoxins, including aflatoxins, fumonisins, group B trichothecenes (primarily deoxynivalenol), ochratoxin A, and zearalenone. This review describes the basic principles of FPIA and summarizes recent research in this area with regard to mycotoxins.
|
|
Received: 10 December 2009; in revised form: 18 January 2010 / Accepted: 21 January 2010 / Published: 2 February 2010
Show/Hide Abstract
| Download PDF Full-text (46 KB)
Abstract: It has been brought to our attention by a member of our Editorial Board that substantial portions of this review article have been copied verbatim from earlier publications without credit. After comparing the present paper and the other sources we have determined that indeed this manuscript clearly violates our policy on originality of all material submitted for publication and the generally accepted ethics of scientific publication. Consequently, the Editorial Team and Publisher have determined that it should be retracted. We apologize for any inconvenience this may cause.
|
|
Received: 5 January 2010; in revised form: 17 February 2010 / Accepted: 23 February 2010 / Published: 25 February 2010
Show/Hide Abstract
| Download PDF Full-text (593 KB) | Download XML Full-text
Abstract: Grain products are a staple of diets worldwide and therefore, the ability to accurately and efficiently detect foodborne contaminants such as mycotoxins is of importance to everyone. Here we describe an indirect competitive fluid array fluoroimmunoassay to quantify the mycotoxins, fumonisin B1 and ochratoxin A. Both toxins were immobilized to the surface of microspheres using a variety of intermediate molecules and binding of biotinylated "tracer" antibody tracers determined through flow cytometry using streptavidin-phycoerythrin conjugates and the Luminex100 flow cytometer. Competitive assays were developed where the binding of biotinylated monoclonal antibodies to fumonisin B and ochratoxin A was competitively inhibited by different concentrations of those toxins in solution. Concentrations of fumonisin giving 50% inhibition were 300 pg/mL in buffer, 100 ng/g in spiked oats, and 1 μg/g in spiked cornmeal; analogous concentrations for ochratoxin A were 30 ng/mL in buffer, 30 ng/g in spiked oats, and 10 ng/g in spiked corn. The future challenge will be to expand the number of mycotoxins tested both individually and in multiplexed format using this platform.
|
|
Received: 28 January 2010; in revised form: 12 March 2010 / Accepted: 15 March 2010 / Published: 18 March 2010
Show/Hide Abstract
| Download PDF Full-text (283 KB) | Download XML Full-text
Abstract: Mycotoxigenic fungi colonizing food matrices are inevitably competing with a wide range of other resident fungi. The outcomes of these interactions are influenced by the prevailing environmental conditions and the competing species. We have evaluated the competitiveness of F. culmorum and A. carbonarius in the grain and grape food chain for their in vitro and in situ dominance in the presence of other fungi, and the effect that such interactions have on colony interactions, growth and deoxynivalenol (DON) and ochratoxin A (OTA) production. The Index of Dominance shows that changes in water activity (aw) and temperature affect the competitiveness of F. culmorum and A. carbonarius against up to nine different fungi. Growth of both mycotoxigenic species was sometimes inhibited by the presence of other competing fungi. For example, A. niger uniseriate and biseriate species decreased growth of A. carbonarius, while Aureobasidium pullulans and Cladosporium species stimulated growth. Similar changes were observed when F. graminearum was interacting with other grain fungi such as Alternaria alternata, Cladopsorium herbarum and Epicoccum nigrum. The impact on DON and OTA production was very different. For F. culmorum, the presence of other species often inhibited DON production over a range of environmental conditions. For A.carbonarius, on a grape–based medium, the presence of certain species resulted in a significant stimulation of OTA production. However, this was influenced by both temperature and aw level. This suggests that the final mycotoxin concentrations observed in food matrices may be due to complex interactions between species and the environmental history of the samples analyzed.
|
|
Received: 19 February 2010; in revised form: 16 March 2010 / Accepted: 17 March 2010 / Published: 24 March 2010
Show/Hide Abstract
| Download PDF Full-text (349 KB) | Download XML Full-text
Abstract: Environmental stimuli trigger an adaptative cellular response to optimize the probability of survival and proliferation. In eukaryotic organisms from mammals to fungi osmotic stress, mainly through the action of the high osmolarity glycerol (HOG) pathway, leads to a response necessary for adapting and surviving hyperosmotic environments. In this review we show that the osmoadaptative response is conserved but not identical in different fungi. The osmoadaptative response system is also intimately linked to morphogenesis in filamentous fungi, including mycotoxin producers. Previous studies indicate that the response to osmotic stress is also coupled to the biosynthesis of natural products, including mycotoxins.
|
|
Received: 29 January 2010; in revised form: 23 February 2010 / Accepted: 19 March 2010 / Published: 24 March 2010
Show/Hide Abstract
| Download PDF Full-text (361 KB) | Download XML Full-text
Abstract: An electrochemical affinity sensor for the determination of fumonisins mycotoxins (Fms) using monoclonal antibody modified screen-printed gold electrode with carbon counter and silver-silver chloride pseudo-reference electrode is reported in this work. A direct competitive enzyme-linked immunosorbent assay (ELISA) was initially developed, exhibiting a detection limit of 100 µg·L-1for fumonisins. This was then transferred to the surface of a bare gold screen-printed electrode (SPGE) and detection was performed by chronoamperometry, monitoring the reaction of 3,3’,5,5’-Tetramethylbenzidine dihydrochloride (TMB) and hydrogen peroxide (H2O2) catalysed by HRP at −100 mV potential vs. onboard Ag-AgCl pseudo-reference electrode. The immunosensor exhibited detection limit of 5 µg·L−1 fumonisins with a dynamic range from 1 µg·L−1–1000 µg·L−1. The sensor also performed well in extracted corn samples.
|
|
Received: 27 January 2010; in revised form: 15 March 2010 / Accepted: 19 March 2010 / Published: 24 March 2010
Show/Hide Abstract
| Download PDF Full-text (800 KB) | Download XML Full-text
Abstract: The black spored fungi of the subgenera Circumdata,the section Nigri (=Aspergillus niger group) is reviewed relative to their production of mycotoxins and their effects on plants as pathogens. Molecular methods have revealed more than 18 cryptic species, of which several have been characterized as potential mycotoxin producers. Others are defined as benign relative to their ability to produce mycotoxins. However, these characterizations are based on in vitro culture and toxins production. Several can produce the ochratoxins that are toxic to livestock, poultry, and humans. The black aspergilli produce rots of grapes, maize, and numerous other fruits and grain and they are generally viewed as post-harvest pathogens. Data are review to suggest that black aspergilli, as so many others, are symptomless endophytes. These fungi and their mycotoxins contaminate several major grains, foodstuffs, and products made from them such as wine, and coffee. Evidence is presented that the black aspergilli are producers of other classes of mycotoxins such as the fumonisins, which are known carcinogenic and known prior investigations as being produced by the Fusarium species. Three species are identified in U.S. maize and peanuts as symptomless endophytes, which suggests the potential for concern as pathogens and as food safety hazards.
|
|
Received: 4 February 2010; in revised form: 12 March 2010 / Accepted: 31 March 2010 / Published: 1 April 2010
Show/Hide Abstract
| Download PDF Full-text (522 KB) | Download XML Full-text
Abstract: Mycotoxins are toxic compounds, produced by the secondary metabolism of toxigenic moulds in the Aspergillus, Alternaria, Claviceps, Fusarium, Penicillium and Stachybotrys genera occurring in food and feed commodities both pre- and post-harvest. Adverse human health effects from the consumption of mycotoxins have occurred for many centuries. When ingested, mycotoxins may cause a mycotoxicosis which can result in an acute or chronic disease episode. Chronic conditions have a much greater impact, numerically, on human health in general, and induce diverse and powerful toxic effects in test systems: some are carcinogenic, mutagenic, teratogenic, estrogenic, hemorrhagic, immunotoxic, nephrotoxic, hepatotoxic, dermotoxic and neurotoxic. Although mycotoxin contamination of agricultural products still occurs in the developed world, the application of modern agricultural practices and the presence of a legislatively regulated food processing and marketing system have greatly reduced mycotoxin exposure in these populations. However, in developing countries, where climatic and crop storage conditions are frequently conducive to fungal growth and mycotoxin production, much of the population relies on subsistence farming or on unregulated local markets. Therefore both producers and governmental control authorities are directing their efforts toward the implementation of a correct and reliable evaluation of the real status of contamination of a lot of food commodity and, consequently, of the impact of mycotoxins on human and animal health.
|
|
Received: 2 February 2010; in revised form: 4 March 2010 / Accepted: 10 March 2010 / Published: 5 April 2010
Show/Hide Abstract
| Download PDF Full-text (380 KB) | Download XML Full-text
Abstract: Patulin is a toxic chemical contaminant produced by several species of mold, especially within Aspergillus, Penicillium and Byssochlamys. It is the most common mycotoxin found in apples and apple-derived products such as juice, cider, compotes and other food intended for young children. Exposure to this mycotoxin is associated with immunological, neurological and gastrointestinal outcomes. Assessment of the health risks due to patulin consumption by humans has led many countries to regulate the quantity in food. A full understanding of the molecular genetics of patulin biosynthesis is incomplete, unlike other regulated mycotoxins (aflatoxins, trichothecenes and fumonisins), although the chemical structures of patulin precursors are now known. The biosynthetic pathway consists of approximately 10 steps, as suggested by biochemical studies. Recently, a cluster of 15 genes involved in patulin biosynthesis was reported, containing characterized enzymes, a regulation factor and transporter genes. This review includes information on the current understanding of the mechanisms of patulin toxinogenesis and summarizes its toxicological effects.
|
|
Received: 28 February 2010; in revised form: 15 April 2010 / Accepted: 19 April 2010 / Published: 26 April 2010
Show/Hide Abstract
| Download PDF Full-text (128 KB) | Download XML Full-text
Abstract: Host resistance has become a viable approach to eliminating aflatoxin contamination of maize since the discovery of several maize lines with natural resistance. However, to derive commercial benefit from this resistance and develop lines that can aid growers, markers need to be identified to facilitate the transfer of resistance into commercially useful genetic backgrounds without transfer of unwanted traits. To accomplish this, research efforts have focused on the identification of kernel resistance-associated proteins (RAPs) including the employment of comparative proteomics to investigate closely-related maize lines that vary in aflatoxin accumulation. RAPs have been identified and several further characterized through physiological and biochemical investigations to determine their causal role in resistance and, therefore, their suitability as breeding markers. Three RAPs, a 14 kDa trypsin inhibitor, pathogenesis-related protein 10 and glyoxalase I are being investigated using RNAi gene silencing and plant transformation. Several resistant lines have been subjected to QTL mapping to identify loci associated with the aflatoxin-resistance phenotype. Results of proteome and characterization studies are discussed.
|
Last update: 12 January 2011
