Thermal stability of moniliformin at varying temperature, pH, and time in an aqueous environment

The Fungal Microbiome of Wheat Flour Includes Potential Mycotoxin Producers

Consumers are increasingly demanding higher quality and safety standards for the products they consume, and one of this is wheat flour, the basis of a wide variety of processed products. This major component in the diet of many communities can be contaminated by microorganisms before the grain harvest, or during the grain storage right before processing. These microorganisms include several fungal species, many of which produce mycotoxins, secondary metabolites that can cause severe acute and chronic disorders. Yet, we still know little about the overall composition of fungal communities associated with wheat flour. In this study, we contribute to fill this gap by characterizing the fungal microbiome of different types of wheat flour using culture-dependent and -independent techniques. Qualitatively, these approaches suggested similar results, highlighting the presence of several fungal taxa able to produce mycotoxins. In-vitro isolation of fungal species suggest a higher frequency of Penicillium, while metabarcoding suggest a higher abundance of Alternaria. This discrepancy might reside on the targeted portion of the community (alive vs. overall) or in the specific features of each technique. Thus, this study shows that commercial wheat flour hosts a wide fungal diversity with several taxa potentially representing concerns for consumers, aspects that need more attention throughout the food production chain.

In vitro screening of 65 mycotoxins for insecticidal potential

The economic losses and threats to human and animal health caused by insects and the pathogens transmitted by them require effective and environmentally-friendly methods of controlling them. One such group of natural biocontrol agents which may be used as biopesticides is that of the entomopathogenic fungi and their toxic secondary metabolites (mycotoxins). The present in vitro work examined the insecticidal potential of 65 commercially-available mycotoxins against the insect Sf-9 cell line. Mammalian Caco-2 and THP-1 cell lines served as reference controls to select insecticidal mycotoxins harmless to mammalian cells. All tested mycotoxins significantly reduced the in vitro proliferation of the Sf-9 cells and evoked morphological changes. Ten of the mycotoxins found to strongly inhibit Sf-9 proliferation also had moderate or no effect on Caco-2 cells. The THP-1 cells were highly resistant to the tested mycotoxins: doses 10³ times higher were needed to affect viability and morphology (1 μg/ml for THP-1 versus 1 ng/ml for Sf-9 and Caco-2). Nine mycotoxins significantly decreased Sf-9 cell proliferation with minor effects on mammalian cells: cyclosporins B and D, cytochalasin E, gliotoxin, HC toxin, paxilline, penitrem A, stachybotrylactam and verruculogen. These may be good candidates for future biopesticide formulations.

Mycotoxins during the Processes of Nixtamalization and Tortilla Production

Tortillas are a traditional staple food in Mesoamerican cuisine, which have also become popular on a global level, e.g., for wraps or as snacks (tortilla chips). Traditional tortilla production includes alkaline cooking (nixtamalization) of maize kernels. This article summarizes the current knowledge on mycotoxin changes during the nixtamalization of maize and tortilla production. Upon nixtamalization, mycotoxins can be affected in different ways. On the one hand, the toxins can be physically removed during steeping and washing. On the other hand, mycotoxins might be degraded, modified, or released/bound in the matrix by high pH and/or high temperature. This also applies to the subsequent baking of tortillas. Many studies have shown reduced mycotoxin levels in alkali-cooked maize and in tortillas. Most of the available data relate to aflatoxins and fumonisins. The reduction (and detoxification) of aflatoxins during nixtamalization might, however, be partially reversed in acidic conditions. The loss of fumonisin concentrations is to some extent accompanied by hydrolyzation and by lower toxicity. However, some studies have indicated the potential formation of toxicologically relevant modified forms and matrix-associated fumonisins. More data are required to assess the influence of alkaline cooking regarding such modified forms, as well as mycotoxins other than aflatoxins/fumonisins.

Risks to human and animal health related to the presence of moniliformin in food and feed

Moniliformin (MON) is a mycotoxin with low molecular weight primarily produced by Fusarium fungi and occurring predominantly in cereal grains. Following a request of the European Commission, the CONTAM Panel assessed the risk of MON to human and animal health related to its presence in food and feed. The limited information available on toxicity and on toxicokinetics in experimental and farm animals indicated haematotoxicity and cardiotoxicity as major adverse health effects of MON. MON causes chromosome aberrations in vitro but no in vivo genotoxicity data and no carcinogenicity data were identified. Due to the limitations in the available toxicity data, human acute or chronic health‐based guidance values (HBGV) could not be established. The margin of exposure (MOE) between the no‐observed‐adverse‐effect level (NOAEL) of 6.0 mg/kg body weight (bw) for cardiotoxicity from a subacute study in rats and the acute upper bound (UB) dietary exposure estimates ranged between 4,000 and 73,000. The MOE between the lowest benchmark dose lower confidence limit (for a 5% response ‐ BMDL₀₅) of 0.20 mg MON/kg bw per day for haematological hazards from a 28‐day study in pigs and the chronic dietary human exposure estimates ranged between 370 and 5,000,000 for chronic dietary exposures. These MOEs indicate a low risk for human health but were associated with high uncertainty. The toxicity data available for poultry, pigs, and mink indicated a low or even negligible risk for these animals from exposure to MON in feed at the estimated exposure levels under current feeding practices. Assuming similar or lower sensitivity as for pigs, the CONTAM Panel considered a low or even negligible risk for the other animal species for which no toxicity data suitable for hazard characterisation were identified. Additional toxicity studies are needed and depending on their outcome, the collection of more occurrence data on MON in food and feed is recommended to enable a comprehensive human risk assessment.

Mitigation of enniatins in edible fish tissues by thermal processes and identification of degradation products

Emerging mycotoxins, such as enniatins and beauvericin, are common contaminants in vegetal matrices, but recently, the occurrence of mycotoxins in foodstuffs from animal origin has been also reported as they can be present in edible tissues of animals fed with contaminated feedstuffs. Sea bass, sea bream, Atlantic salmon and rainbow trout from aquaculture analyzed in the present survey showed contamination by emerging Fusarium mycotoxins enniatins (ENs). ENs were extracted from raw and cooked fish with acetonitrile and analyzed by Liquid Chromatography coupled to Mass Spectrometry. In this study, the stability of ENs was evaluated during food processing by the application of different cooking methods (broiling, boiling, microwaving and baking treatments). All treated samples showed a reduction in mycotoxin levels with different percentages depending on the type of EN and the fish species. Thus, the reduction obtained ranged from 30 to 100%. The thermal treatments have shown to be a good strategy to mitigate ENs content in edible fish tissues. On the other hand, some ENs degradation products originated during the application of thermal treatments were identified.

Genetic variation of Fusarium oxysporum isolates forming fumonisin B(1) and moniliformin

Thirty single-spore isolates of a toxigenic fungus, Fusarium oxysporum, were isolated from asparagus spears and identified by species-specific polymerase chain reaction (PCR) and translation elongation factor 1-α (TEF) sequence analysis. In the examined sets of F. oxysporum isolates, the DNA sequences of mating type genes (MAT) were identified. The distribution of MAT idiomorph may suggest that MAT1-2 is a predominant mating type in the F. oxysporum population. F. oxysporum is mainly recognised as a producer of moniliformin-the highly toxic secondary metabolite. Moniliformin content was determined by high-performance liquid chromatography (HPLC) analysis in the range 0.05-1,007.47 μg g(-1) (mean 115.93 μg g(-1)) but, also, fumonisin B(1) was detected, in the concentration range 0.01-0.91 μg g(-1) (mean 0.19 μg g(-1)). There was no association between mating types and the mycotoxins biosynthesis level. Additionally, a significant intra-species genetic diversity was revealed and molecular markers associated with toxins biosynthesis were identified.

Free Radicals, Salicylic Acid and Mycotoxins in Asparagus After Inoculation with Fusarium proliferatum and F. oxysporum

Electron paramagnetic resonance was used to monitor free radicals and paramagnetic species like Fe, Mn, Cu generation, stability and status in Asparagus officinalis infected by common pathogens Fusarium proliferatum and F. oxysporum. Occurrence of F. proliferatum and F. oxysporum, level of free radicals and other paramagnetic species, as well as salicylic acid and mycotoxins content in roots and stems of seedlings were estimated on the second and fourth week after inoculation. In the first term free and total salicylic acid contents were related to free radicals level in stem (P = 0.010 and P = 0.033, respectively). Concentration of Fe(3+) ions in porphyrin complexes (g = 2.3, g = 2.9) was related to the species of pathogen. There was no significant difference between Mn(2+) concentrations in stem samples; however, the level of free radicals in samples inoculated with F. proliferatum was significantly higher when compared to F. oxysporum.

Health effects of moniliformin: a poorly understood Fusarium mycotoxin

The contamination of the food and feed chain with mycotoxins and the subsequent threat to human health and animal welfare is evident. Today mycotoxin research is still strongly focused on mycotoxins such as aflatoxins, ochratoxin A and for Fusarium fungi mainly the trichothecenes deoxynivalenol (DON) and T-2 and HT-2 toxins. However, fungi of the Fusarium genus are clearly capable of synthesising other mycotoxins as well, including moniliformin (MON). The occurrence of MON is worldwide and the levels in grains vary from below the limit of quantification to the highest detected value in maize intended for human consumption being close to 20 mg/kg. In Finland and Norway, the reported levels are typically a few hundreds of micrograms per kilogram. The toxicology of MON is not well understood. It is characterised by major species differences but typically MON evokes myocardiac damage. For MON, No Observed Adverse Effect Level (NOAEL) has not been established and a provisional Tolerable Daily Intake (pTDI) value has not been proposed. In our risk assessment, we applied a NOAEL value of 10 mg/kg bw/day which is based on our unpublished subchronic exposure experiments. By applying this value in the risk assessment combined with the estimated intakes from food in Finland and Norway, it seems that MON per se does not pose a clear threat to human health at current levels. On the other hand, one needs to bear in mind the concurrent exposure to other mycotoxins and the fact that the risk assessment of mycotoxin mixtures are in their infancy.

Reaction of winter wheat (Triticum aestivum L.) cultivars to infection with Fusarium spp.: mycotoxin contamination in grain and chaff

This study compares the susceptibility of winter wheat (Triticum aestivum L.) cultivars to Fusarium head blight (FHB) and accumulation of mycotoxins in kernels and chaff under different climatic conditions in two locations-Cerekwica near Poznan (Central West Poland) and Sitaniec, near Zamosc, Lublin region (South East Poland). Very high variations were found in the concentrations of mycotoxins (zearalenone, ZEA; nivalenol, NIV; deoxynivalenol, DON; moniliformin, MON) in examined fractions: Fusarium-damaged kernels (FDK) and healthy looking kernels (HLK) and in chaff for individual cultivars in both locations. In most cases, significantly higher concentrations of investigated toxins were recorded in wheat from the area of Lublin than from Poznan (p < 0.05). The highest Fusarium infection rates and mycotoxin biosynthesis levels were observed in the Lublin location, with the percentage of the FDK fraction ranging 8.1-81.6. In this region, ZEA concentration (microg g(-1)) after inoculation with F. culmorum and F. graminearum ranged from 0.02-0.48 and 0.32-1.04, respectively. In the Poznan area, the toxin concentrations were considerably lower, ranging 0.01-0.10 and 0.03-0.13 microg g(-1) for both isolates, respectively. The concentration of DON was significantly higher than ZEA or NIV levels. The levels of MON accumulation (microg g(-1)) in the FDK fraction were between 0.14 and 1.73 (Poznan area) and ND (not detected) to 2.51 (Lublin area). F. avenaceum infection rate ranged 7-35% in samples where the toxin was detected.

Formation of fumonisins and other secondary metabolites by Fusarium oxysporum and F. proliferatum: a comparative study

The principal aim of this study was to estimate the formation of fumonisins (FB(1) and FB(2)), moniliformin (MON), and ergosterol (ERG) by Fusarium oxysporum and Fusarium proliferatum, while the formation of beauvericin (BEA) was estimated by the latter Fusarium species only. Moreover, the effect of temperature on the biosynthesis of mycotoxins was also evaluated. Fumonisins were formed by F. proliferatum, with the highest yield at 18 degrees C (720.0-1976.6 microg g(-1) for FB(1), 74.2-670.8 microg g(-1) for FB(2)) and only by three of four F. oxysporum strains at a very low level (0.02-4.77 microg g(-1) for FB(1), 0.02-2.15 microg g(-1) for FB(2)). The amount of MON formed by F. proliferatum was the highest (p < 0.001) at 32 degrees C (3056.87 microg g(-1)), while MON biosynthesis by F. oxysporum was lower 227.54 microg g(-1) (p < 0.001). BEA was produced by F. proliferatum with the highest level at 25 degrees C (p < 0.001). ERG-recognized as an indicator of fungal biomass development and as a consequence of mycotoxin formation-was found at the highest concentration at a biosynthesis temperature of 25 degrees C for F. proliferatum and F. oxysporum (p < 0.001).

Strategies to Prevent Mycotoxin Contamination of Food and Animal Feed: A Review

Mycotoxins are fungal secondary metabolites that have been associated with severe toxic effects to vertebrates produced by many important phytopathogenic and food spoilage fungi including Aspergillus, Penicillium, Fusarium, and Alternaria species. The contamination of foods and animal feeds with mycotoxins is a worldwide problem. We reviewed various control strategies to prevent the growth of mycotoxigenic fungi as well as to inhibit mycotoxin biosynthesis including pre-harvest (resistance varieties, field management and the use of biological and chemical agents), harvest management, and post-harvest (improving of drying and storage conditions, the use of natural and chemical agents, and irradiation) applications. While much work in this area has been performed on the most economically important mycotoxins, aflatoxin B(1) and ochratoxin A much less information is available on other mycotoxins such as trichothecenes, fumonisin B(1), zearalenone, citrinin, and patulin. In addition, physical, chemical, and biological detoxification methods used to prevent exposure to the toxic and carcinogenic effect of mycotoxins are discussed. Finally, dietary strategies, which are one of the most recent approaches to counteract the mycotoxin problem with special emphasis on in vivo and in vitro efficacy of several of binding agents (activated carbons, hydrated sodium calcium aluminosilicate, bentonite, zeolites, and lactic acid bacteria) have also been reviewed.

Presence and concentrations of the Fusarium-related mycotoxins beauvericin, enniatins and moniliformin in finnish grain samples

Fusarium mycotoxins beauvericin, enniatins (A, A1, B, B1) and moniliformin were analysed in 38 Finnish grain samples (14 wheat, 22 barley, one rye, one oats) harvested in 2001-02. The contaminating Fusarium species were identified with the primer-specific polymerase chain reaction as well as with morphological studies. All the studied mycotoxins were found in the samples. Enniatins B and B1 were detected in all samples, and enniatin A, enniatin A1, beauvericin and moniliformin in 74, 95, 95 and 74% of the samples, respectively. There were higher concentrations of the mycotoxins analysed in 2001 compared with 2002. The highest levels of mycotoxins were detected in samples harvested late in the autumn after a long rainy period. Fusarium avenaceum was the most abundant Fusarium species in Finland during both years (0-29.5%) measured as infected kernels. A significant correlation was found between F. avenaceum contamination level and the concentration levels of enniatins B and B1, as well as moniliformin.

Levels of mycotoxins and sample cytotoxicity of selected organic and conventional grain-based products purchased from Finnish and Italian markets

The contamination levels of 16 different Fusarium- and Aspergillus-mycotoxins were chemically determined from randomly selected organic and conventional grain-based products purchased from Finnish and Italian markets. The cytotoxicity of the samples was analyzed with an in vitro test using feline fetal lung cells. Overall, the concentrations of the mycotoxins studied were low in all of the samples. Enniatins B and B1 as well as deoxynivalenol were the most predominant mycotoxins in the samples, being present in 97%, 97%, and 90% of the samples, respectively. The geographical origin or the agricultural practice had no influence on the mycotoxin concentrations of the samples. The babyfoods included in the samples had significantly lower concentrations of mycotoxins than the other products with a mean total mycotoxin content of 47 microg/kg compared with 99 microg/kg for the other kinds of food. All the samples evoked toxicity in the in vitro test, but no correlation between cytotoxicity and the mycotoxin concentrations was observed.