Development and validation of a liquid chromatography/tandem mass spectrometric method for the determination of 39 mycotoxins in wheat and maize

Physico-chemical characteristics and fungal profile of four Saudi fresh date (Phoenix dactylifera L.) cultivars

Physico-chemical and microbial analyses of four commercial fresh date cultivars (Sukari, Barhi, Khalas and Rothana) grown in Saudi Arabia were evaluated. Colorimetric assay indicated that Sukari had the highest total sugar content of 13.21g/100gFW while the lowest was in Rothana with 7.96g/100gFW. Total phenolic content (TPC) ranged from 76.74 to 122.20mgGAE/100gFW in Barhi and Rothana respectively, whereas antioxidant activity was highest in Sukari (105.99μgGAE/gFW) and lowest in Khalas (90.81μgGAE/gFW). The dominant fungal genera were Aspergillus sp., Rhizopus sp., Penicillium sp. and Sarocladium sp., occurring at 37, 18, 13 and 12% respectively. The highest fungal occurrence was in Barhi (30%) followed by Sukari (29%), Khalas (26%) and Rothana (15%). The TPC had a negative correlation with fungal occurrence whilst the total sugars had a positive correlation.

Mycotoxin Contamination in Sugarcane Grass and Juice: First Report on Detection of Multiple Mycotoxins and Exposure Assessment for Aflatoxins B₁ and G₁ in Humans

This study was conducted to investigate the natural co-occurrence of multiple toxic fungal and bacterial metabolites in sugarcane grass and juice intended for human consumption in Upper Egypt. Quantification of the target analytes has been done using the "dilute and shoot" approach followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total number of 29 and 33 different metabolites were detected in 21 sugarcane grass and 40 juice samples, respectively, with a trend of concentrations being higher in grass than in juice. Among the regulated mycotoxins, only aflatoxin B₁ (AFB₁) and aflatoxin G₁ (AFG₁) were detected. The prevalence of AFB₁ was in 48% of grass samples and in 58% of juice with a maximum concentration of 30.6 μg/kg and 2.10 μg/kg, respectively. AFG₁ was detected in 10% of grass samples (7.76 μg/kg) and 18% of juice samples (34 μg/kg). Dietary exposure was assessed using a juice frequency questionnaire of adult inhabitants in Assiut City. The assessment revealed different levels of exposure to AFB₁ between males and females in winter and summer seasons. The estimated seasonal exposure ranged from 0.20 to 0.40 ng/kg b.w./day in winter and from 0.38 to 0.90 ng/kg b.w./day in summer.

Flow cytometry based rapid duplexed immunoassay for fusarium mycotoxins

At small food processing facilities, the most frequently used test to determine if grain-derived mycotoxin concentrations are compliant with legal limits is the enzyme-linked immunosorbent assay (ELISA). Each kit is designed to detect one of the six dangerous mycotoxins. With the increasing occurrence of coinfection of grain with multiple-mycotoxins in the field and/or during storage, ELISA is no longer a cost effective best assay option. With ELISA, each species of mycotoxin requires different sample preparation/extraction and a 45 min incubation. The alternative multiplexed assay presented here, the competitive fluorescent microsphere immunoassay (CFIA), follows current food safety standards. It handles several toxins simultaneously with a single universal extraction protocol. The authors' objective was to modify an existing commercial CFIA kit developed for bench top flow cytometry and extend its utility for point-of-need (PON) applications. The accelerated protocol offers over 60% reduction in total processing time and it detects dual mycotoxin contamination simultaneously. The observed enhanced binding kinetics equations reported here utilizing suspended solid phase particles in liquid phase, are also supported by published theoretical calculations. In the near future portable cytometry may bring rapid multiplexed PON testing to assure the safety of small food processing installations. © 2016 International Society for Advancement of Cytometry.

Towards the development of innovative multi-mycotoxin reference materials as promising metrological tool for emerging and regulated mycotoxin analyses

The interest in LC-MS/MS multi-mycotoxin methods unveiled an urgent need for multi-mycotoxin reference material. A multi-fusariotoxin, including deoxynivalenol (DON); zearalenone (ZEN); T-2 toxin (T-2); HT-2 toxin (HT-2); enniatin A, A1, B, and B1 (ENNs); and beauvericin (BEA), contaminated wheat flour was obtained by inoculation Fusarium spp. strains. The candidate material has successfully passed the homogeneity test and submitted to an international interlaboratory study achieved by 19 laboratories from 11 countries using their routine analytical method. The dispersion of the results for ZEN and BEA did not allow the derivation of reliable consensus values, while the assignment was only possible for DON, HT-2, T-2, and ENN A. No link was found between the methods used by the participants and the results. Significant changes in dry matter contents (≥±1.4 % of the initial dry matter) and significant changes in ergosterol contents (≥±10 %) did not occur. Using the mycotoxin contents in wheat flour stored at -80 °C as reference values, statistically significant decreases were observed only for T-2 contents at +24 °C, in contrast to the storage at -20 and +4 °C. For the other involved toxins, the candidate material was found to be stable at -20, +4, or +24 °C. Based on the T-2 decreases, a shelf life of 6 years was derived from isochronous study when the material is kept at -20 °C. At room temperature (e.g., +24 °C) or higher, this time validity drastically decreases down to 6 months. The development of this metrological tool is an important step towards food and feed quality control using multi-mycotoxin analyses. In vivo animal experiments using multi-mycotoxin-contaminated feeds dealing with the carryover or mitigation could further benefit from the methodology of this work.

Challenges in the analysis of multiple mycotoxins

The problems associated with different groups or ‘families’ of mycotoxins have been known for some time, and for many years certain groups of mycotoxins have been known to co-occur in commodities and foods. Until fairly recently commodities and foods were analysed for individual toxins or groups of related toxins and attempts to measure multiple groups of toxins required significant investments in terms of time, effort, and expense. Analytical technologies using both the instrument-intensive techniques, such as mass spectrometry, and screening techniques, such as immunoassays, have progressed significantly in recent years. This has led to the proliferation of techniques capable of detecting multiple groups of mycotoxins using a variety of approaches. Despite considerable progress, the challenges for routine monitoring of multiple toxins continue. Certain of these challenges, such as the need for co-extraction of multiple analytes with widely different polarities and the potential for carry-over of matrix components that can influence the results, are independent of the analytical technique (MS or immunoassay) used. Because of the wide variety of analytical platforms used for multi-toxin analysis, there are also specific challenges that arise amongst the analytical platforms. We showed that chromatographic methods with optical detection for aflatoxins maintain stable response factors over rather long periods. This offers the potential to reduce the analytical burden, provided the use of a single signal receives general acceptance once shown in practise as working approach. This must however be verified by a larger community of laboratories. For immunosensors the arising challenges include the reusability of sensors and, for chromatography-based assays they include the selection of appropriate calibration systems. In this article we seek to further describe the challenges associated with multi-toxin analysis and articulate how such challenges have recently been addressed.

Masked mycotoxins: does breeding for enhanced Fusarium head blight resistance result in more deoxynivalenol-3-glucoside in new wheat varieties?

From economic and environmental points of view, enhancing resistance to Fusarium head blight (FHB) in wheat is regarded as the best option to reduce fungal colonisation and the concomitant mycotoxin contamination. This review focuses on the effect of FHB resistance on deoxynivalenol (DON) and the masked metabolite deoxynivalenol-3-glucoside (DON-3-glucoside) in wheat. Based on published information complemented with our own results we draw the following conclusions: (1) All investigated wheat cultivars can convert DON to DON-3-glucoside. Hence, detoxification of DON to DON-3-glucoside is not a new trait introduced by recent resistance breeding against FHB. (2) The amount of DON-3-glucoside relative to DON contamination can be substantial (up to 35%) and is among other things dependent on genetic and environmental factors. (3) Correlation analyses showed a highly significant relationship between the amount of FHB symptoms and DON contamination: breeding for FHB resistance reduces DON contamination. (4) DON contamination data are highly correlated with DON-3-glucoside concentration data: in other words, reduction of DON content through resistance breeding results in a concomitant reduction in DON-3-glucoside content. (5) The DON-3-glucoside/DON ratio increases with decreasing DON contamination: the most resistant lines with the lowest DON contamination show the highest relative level of DON-3-glucoside to DON. In summary, introgressing FHB resistance reduces both DON and DON-3-glucoside levels in the grain, but the reduction is lower for the masked toxin. DON-3-glucoside can represent a possible hazard to human and animal health, especially in wheat samples contaminated with DON close to permitted limits.

Pentahydroxyscirpene-Producing Strains, Formation In Planta, and Natural Occurrence

Trichothecenes are a class of structurally diverse mycotoxins with more than 200 naturally occurring compounds. Previously, a new compound, pentahydroxyscirpene (PHS), was reported as a byproduct of a nivalenol producing Fusarium strain, IFA189. PHS contains a hydroxy group at C-8 instead of the keto group of type B trichothecenes. In this work, we demonstrate that IFA189 belongs to the species Fusarium kyushuense using molecular tools. Production of PHS in vitro was also observed for several isolates of other Fusarium species producing nivalenol. Furthermore, we report the formation of 4-acetyl-PHS by F. kyushuense on inoculated rice. Wheat ears of the variety Remus were infected with IFA189 and the in planta production of PHS was confirmed. Natural occurrence of PHS was verified in barley samples from the Czech Republic using a liquid chromatographic-tandem mass spectrometric method validated for this purpose. Toxicity of PHS to wheat ribosomes was evaluated with a coupled in vitro transcription and translation assay, which showed that PHS inhibits protein biosynthesis slightly less than nivalenol and deoxynivalenol.

Effects of Citric and Lactic Acid on the Reduction of Deoxynivalenol and Its Derivatives in Feeds

Exposure to mycotoxin-contaminated feeds represents a serious health risk. This has necessitated the need for the establishment of practical methods for mycotoxin decontamination. This study investigated the effects of citric acid (CA) and lactic acid (LA) on common trichothecene mycotoxins in feeds contaminated with Fusarium mycotoxins. Contaminated feed samples were processed either with 5% CA or 5% LA solutions in a ratio of 1:1.2 (w/v) for 5, 24, or 48 h, and analyzed for multiple mycotoxin metabolites using a liquid chromatography-tandem mass spectrometric method. The analyses showed that treating the feed with CA and LA lowered the concentration of deoxynivalenol (DON), whereby 5% LA lowered the original DON concentration in the contaminated feed samples by half, irrespective of the processing time. Similar lowering effects were observed for the concentrations of 15Ac-DON, 5-hydroxyculmorin, and sambucinol. The concentration of nivalenol was only lowered by the LA treatment. In contrast, CA and LA treatments showed no or only small effects on the concentration of several mycotoxins and their derivatives, including zearalenone, fumonisins, and culmorin. In conclusion, the present results indicate that the use of 5% solutions of LA and CA might reduce the concentration of common trichothecene mycotoxins, especially DON and its derivate 15Ac-DON. However, further research is required to determine the effect on overall toxicity and to identify the underlying mechanisms.

Comparison of Fusarium graminearum Transcriptomes on Living or Dead Wheat Differentiates Substrate-Responsive and Defense-Responsive Genes

Fusarium graminearum is an opportunistic pathogen of cereals where it causes severe yield losses and concomitant mycotoxin contamination of the grains. The pathogen has mixed biotrophic and necrotrophic (saprophytic) growth phases during infection and the regulatory networks associated with these phases have so far always been analyzed together. In this study we compared the transcriptomes of fungal cells infecting a living, actively defending plant representing the mixed live style (pathogenic growth on living flowering wheat heads) to the response of the fungus infecting identical, but dead plant tissues (cold-killed flowering wheat heads) representing strictly saprophytic conditions. We found that the living plant actively suppressed fungal growth and promoted much higher toxin production in comparison to the identical plant tissue without metabolism suggesting that molecules signaling secondary metabolite induction are not pre-existing or not stable in the plant in sufficient amounts before infection. Differential gene expression analysis was used to define gene sets responding to the active or the passive plant as main impact factor and driver for gene expression. We correlated our results to the published F. graminearum transcriptomes, proteomes, and secretomes and found that only a limited number of in planta- expressed genes require the living plant for induction but the majority uses simply the plant tissue as signal. Many secondary metabolite (SM) gene clusters show a heterogeneous expression pattern within the cluster indicating that different genetic or epigenetic signals govern the expression of individual genes within a physically linked cluster. Our bioinformatic approach also identified fungal genes which were actively repressed by signals derived from the active plant and may thus represent direct targets of the plant defense against the invading pathogen.

In vitro experimental environments lacking or containing soil disparately affect competition experiments of Aspergillus flavus and co-occurring fungi in maize grains

In vitro experimental environments are used to study interactions between microorganisms, and to predict dynamics in natural ecosystems. This study highlights that experimental in vitro environments should be selected to match closely the natural environment of interest during in vitro studies to strengthen extrapolations about aflatoxin production by Aspergillus and competing organisms. Fungal competition and aflatoxin accumulation were studied in soil, cotton wool or tube (water-only) environments, for Aspergillus flavus competition with Penicillium purpurogenum, Fusarium oxysporum or Sarocladium zeae within maize grains. Inoculated grains were incubated in each environment at two temperature regimes (25 and 30°C). Competition experiments showed interaction between the main effects of aflatoxin accumulation and the environment at 25°C, but not so at 30°C. However, competition experiments showed fungal populations were always interacting with their environments. Fungal survival differed after the 72-h incubation in different experimental environments. Whereas all fungi incubated within the soil environment survived, in the cotton wool environment none of the competitors of A. flavus survived at 30°C. With aflatoxin accumulation, F. oxysporum was the only fungus able to interdict aflatoxin production at both temperatures. This occurred only in the soil environment and fumonisins accumulated instead. Smallholder farmers in developing countries face serious mycotoxin contamination of their grains, and soil is a natural reservoir for the associated fungal propagules, and a drying and storage surface for grains on these farms. Studying fungal dynamics in the soil environment and other environments in vitro can provide insights into aflatoxin accumulation post-harvest.

The Microbiome and Metabolites in Fermented Pu-erh Tea as Revealed by High-Throughput Sequencing and Quantitative Multiplex Metabolite Analysis

Pu-erh is a tea produced in Yunnan, China by microbial fermentation of fresh Camellia sinensis leaves by two processes, the traditional raw fermentation and the faster, ripened fermentation. We characterized fungal and bacterial communities in leaves and both Pu-erhs by high-throughput, rDNA-amplicon sequencing and we characterized the profile of bioactive extrolite mycotoxins in Pu-erh teas by quantitative liquid chromatography-tandem mass spectrometry. We identified 390 fungal and 629 bacterial OTUs from leaves and both Pu-erhs. Major findings are: 1) fungal diversity drops and bacterial diversity rises due to raw or ripened fermentation, 2) fungal and bacterial community composition changes significantly between fresh leaves and both raw and ripened Pu-erh, 3) aging causes significant changes in the microbial community of raw, but not ripened, Pu-erh, and, 4) ripened and well-aged raw Pu-erh have similar microbial communities that are distinct from those of young, raw Ph-erh tea. Twenty-five toxic metabolites, mainly of fungal origin, were detected, with patulin and asperglaucide dominating and at levels supporting the Chinese custom of discarding the first preparation of Pu-erh and using the wet tea to then brew a pot for consumption.

Validated UPLC-MS/MS Methods To Quantitate Free and Conjugated Alternaria Toxins in Commercially Available Tomato Products and Fruit and Vegetable Juices in Belgium

Ultraperformance liquid chromatography tandem mass spectrometry and Quick, Easy, Cheap, Effective, Rugged, and Safe based analytical methodologies to quantitate both free (alternariol (1), alternariol monomethyl ether (2), tenuazonic acid (3), tentoxin (4), altenuene (5), altertoxin-I (6)) and conjugated (sulfates and glucosides of 1 and 2) Alternaria toxins in fruit and vegetable juices and tomato products were developed and validated. Acceptable limits of quantitation (0.7-5.7 μg/kg), repeatability (RSDr < 15.7%), reproducibility (RSDR < 17.9%), and apparent recovery (87.0-110.6%) were obtained for all analytes in all matrices investigated. 129 commercial foodstuffs were analyzed, and 3 was detected in 100% of tomato product samples (<LOQ to 333 μg/kg), while 1, 2, 4, and 5 were also frequently detected (21-86%, <LOQ to 62 μg/kg). Moreover, low levels (<LOQ to 9.9 μg/kg) of modified Alternaria toxins (sulfates of 1 and 2) were repeatedly detected. A deterministic dietary exposure assessment revealed the possible risk for human health related to the presence of 1 and 2 in tomato based foodstuffs, whereas 3 is unlikely to be of human health concern.

Development and Validation of an Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry Method for Simultaneous Determination of Four Type B Trichothecenes and Masked Deoxynivalenol in Various Feed Products

A reliable and sensitive analytical method was developed for simultaneous determination of deoxynivalenol(DON), 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON), fusarenon X (FUS-X), and masked deoxynivalenol (deoxynivalenol-3-glucoside, D3G) in formula feed, concentrated feed, and premixed feed products. The method was based on an improved sample pretreatment with the commercially available HLB cartridges used for sample purification and enrichment followed by analysis using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Several key parameters including the extraction solvents, the positions of sample loading solvents, washing and elution solvents for HLB cartridges were carefully optimized to achieve optimal extraction and purification efficiencies. The established method was extensively validated by determining the linearity (R² ≥ 0.99), sensitivity (limit of quantification in the range of 0.08-4.85 μg/kg), recovery (79.3%-108.1%), precision (Intra-day RSDs ≤ 13.5% and Inter-day RSDs ≤ 14.9%), and then was successfully applied to determine the four type B trichothecenes and D3G in a total of 31 feed samples. Among them, 26 were contaminated with various mycotoxins at the levels of 2.1-864.5 μg/kg, and D3G has also been detected in 17 samples with the concentrations in the range of 2.1-34.8 μg/kg, proving the established method to be a valuable tool for type B trichothecenes and masked DON monitoring in complex feed matrices.

Production of the Fusarium Mycotoxin Moniliformin by Penicillium melanoconidium

Moniliformin is a mycotoxin produced by several cereal associated Fusaria. Here, we show for the first time that moniliformin can be produced by the cereal fungus, Penicillium melanoconidium (4 out of 4 strains), but not in the related species in the Viridicata series. Moniliformin was detected in 10 out of 11 media: two agars and several cereal and bean types. Moniliformin was identified by a novel mixed-mode anionic exchange reversed phase chromatographic method which was coupled to both tandem mass spectrometry (MS) and high resolution MS. Mixed-mode chromatography showed superior peak shape compared to that of HILIC and less matrix interference compared to that of reversed phase chromatography, but during a large series of analyses, the column was fouled by matrix interferences. Wheat and beans were artificially infected by P. melanoconidium containing up to 64 and 11 mg/kg moniliformin, respectively, while penicillic acid, roquefortine C, and penitrem A levels in wheat were up to 1095, 38, and 119 mg/kg, respectively.

Dietary exposure to mycotoxins of the Hong Kong adult population from a Total Diet Study

Dietary exposure of Hong Kong adults to mycotoxins and their metabolites including aflatoxins (AFs), ochratoxin A (OTA), fumonisins (FNs), deoxynivalenol (DON), acetyldeoxynivalenols (AcDONs) and zearalenone (ZEA) was estimated using the Total Diet Study (TDS) approach to assess the associated health risk to the local people. Sixty commonly consumed food items, collected in four seasons, were sampled and prepared as consumed. These mycotoxins were primarily found at low levels. The highest mean levels (upper bound) were: AFs, 1.50 µg kg(-)(1) in legumes, nuts and seed; OTA, 0.22 µg kg(-)(1) in sugars and confectionery; FNs, 9.76 µg kg(-)(1) in cereals and their products; DON and AcDONs, 33.1 µg kg(-)(1) in cereals and their products; and ZEA, 53.8 µg kg(-)(1) in fats and oils. The estimated dietary exposures of Hong Kong adults to the mycotoxins analysed were well below the respective health-based guidance values, where available. For AFs, the upper-bound exposure for high consumers is 0.0049 µg kg bw(-)(1) day(-)(1), which was estimated to contribute to about 7.7 (< 1%) of liver cancer cases when compared with 1222 liver cancer cases per year in Hong Kong. The percentage contributions of the estimated 95th percentile dietary exposures (lower and upper bound) to the health-based guidance values of individual mycotoxins were: ochratoxin A, 3.6-9.2%; fumonisins, 0.04-8.5%; deoxynivalenol and acetyldeoxynivalenols, 21.7-28.2%; and zearalenone 3.3-34.5%. The findings indicate that dietary exposures to all the mycotoxins analysed in this study were unlikely to pose an unacceptable health risk to the Hong Kong population.

Presence of Fusarium Species and Other Toxigenic Fungi in Malting Barley and Multi-Mycotoxin Analysis by Liquid Chromatography-High-Resolution Mass Spectrometry

A study was carried out on 43 malting barley samples collected in 2013 across the Umbria region (central Italy) to determine the incidence of the principal mycotoxigenic fungal genera, to identify the Fusarium species isolated from the grains, and to detect the presence of 34 fungal secondary metabolites by liquid chromatography-high-resolution mass spectrometry. The multimycotoxin-method development involved the evaluation of both a two-step solvent and QuEChERS protocol for metabolite extraction. The former protocol was selected because of better accuracy, which was evaluated on the basis of spike-recovery experiments. The most frequently isolated fungal species belonged to the genera Alternaria and Fusarium. The predominant Fusarium species was F. avenaceum, followed by F. graminearum. HT-2 toxin was the most frequently detected mycotoxin, followed by enniatin B, enniatin B1, T-2 toxin, and nivalenol. As a consequence of the observed mixed fungal infections, mycotoxin co-occurrence was also detected. A combination of mycological and mycotoxin analyses allowed the ability to obtain comprehensive information about the presence of mycotoxigenic fungi and their contaminants in malting barley cultivated in a specific geographic area.

Occurrence and exposure assessment of multiple mycotoxins in dried fruits based on liquid chromatography-tandem mass spectrometry

A reliable analytical method based on liquid chromatography-tandem mass spectrometry was developed for simultaneous determination of aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1, aflatoxin G2, ochratoxin A (OTA), deoxynivalenol, T-2 and HT-2 toxin, and zearalenone (ZEA) in various dried fruits. A simple one-step sample extraction without using clean-up cartridges made the established method less labour consuming and less expensive, while optimisation of the several important MS/MS parameters, i.e. the scan time and run segments, ensured its sensitivity and selectivity. After careful validation of the method by determining the linearity (R2>0.99), recovery (77.8-115.9%), precision (relative standard deviation ≤19.5%) and sensitivity (limits of quantification in the range of 0.1-10 μg/kg), a survey of 125 dried fruit samples including 25 pistachios, 28 dried longans, 32 raisins and 40 dried dates randomly collected from different markets in Shanghai, China, was performed. Results revealed that 32.0% of samples were contaminated with different mycotoxins, among which, OTA was the most frequent contaminant with the incidence of 29.6% attaining the concentration levels in the range of 0.4-212.6 μg/kg. ZEA was positively found in 2 pistachio samples with the concentrations of 84.9 μg/kg and 426.9 μg/kg. Trace amounts of AFB1 (0.8 μg/kg) and AFB2 (0.2 μg/kg) were also observed in one pistachio sample and one dried longan sample, respectively. To the best of our knowledge, this is the first report to reveal the real situations of mycotoxin contaminations in various dried fruits in China.

Two-dimensional heart-cut LC-LC improves accuracy of exact-matching double isotope dilution mass spectrometry measurements of aflatoxin B1 in cereal-based baby food, maize, and maize-based feed

Aflatoxins, mycotoxins of fungi of the Aspergillus sp., pose a risk to consumer health and are, therefore, regulated by more than 100 countries. To facilitate method development and validation as well as assessment of measurement capabilities, availability of certified reference materials and proficiency testing schemes is important. For these purposes, highly accurate determinations of the aflatoxin content in the materials used are necessary. We describe here the use of two-dimensional heart-cut LC-LC in combination with exact-matching double isotope dilution mass spectrometry to determine the content of aflatoxin B₁ in three materials used in a proficiency testing scheme. The serious reduction in ionization suppression afforded by the two-dimensional heart-cut LC-LC had a positive effect on the precision of the measured isotope ratios of the exact-matching double isotope dilution mass spectrometry. This is evidenced by the expanded measurement uncertainty (k = 2) of 0.017 μg/kg or 8.9 % relative to a mass fraction of aflatoxin B₁ in a cereal-based baby food of 0.197 μg/kg. This value is in perfect agreement with the consensus value of this material from a proficiency test (PT) scheme for National Reference Laboratories executed by the European Reference Laboratory for Mycotoxins. The effort necessary to perform the described methodology precludes its frequent use but for specific applications we see it as a valuable tool.

Banana peel: an effective biosorbent for aflatoxins

This work reports the application of banana peel as a novel bioadsorbent for in vitro removal of five mycotoxins (aflatoxins (AFB1, AFB2, AFG1, AFG2) and ochratoxin A). The effect of operational parameters including initial pH, adsorbent dose, contact time and temperature were studied in batch adsorption experiments. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and point of zero charge (pHpzc) analysis were used to characterise the adsorbent material. Aflatoxins' adsorption equilibrium was achieved in 15 min, with highest adsorption at alkaline pH (6-8), while ochratoxin has not shown any significant adsorption due to surface charge repulsion. The experimental equilibrium data were tested by Langmuir, Freundlich and Hill isotherms. The Langmuir isotherm was found to be the best fitted model for aflatoxins, and the maximum monolayer coverage (Q0) was determined to be 8.4, 9.5, 0.4 and 1.1 ng mg(-1) for AFB1, AFB2, AFG1 and AFG2 respectively. Thermodynamic parameters including changes in free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were determined for the four aflatoxins. Free energy change and enthalpy change demonstrated that the adsorption process was exothermic and spontaneous. Adsorption and desorption study at different pH further demonstrated that the sorption of toxins was strong enough to sustain pH changes that would be experienced in the gastrointestinal tract. This study suggests that biosorption of aflatoxins by dried banana peel may be an effective low-cost decontamination method for incorporation in animal feed diets.

Ochratoxin A production by Penicillium thymicola

Ochratoxin A (OTA) is a mycotoxin produced by some Aspergillus and Penicillium species that grow on economically important agricultural crops and food products. OTA is classified as Group 2B carcinogen and is potently nephrotoxic, which is the basis for its regulation in some jurisdictions. Using high resolution mass spectroscopy, OTA and ochratoxin B (OTB) were detected in liquid culture extracts of Penicillium thymicola DAOMC 180753 isolated from Canadian cheddar cheese. The genome of this strain was sequenced, assembled and annotated to probe for putative genes involved in OTA biosynthesis. Known OTA biosynthetic genes from Penicillium verrucosum or Penicillium nordicum, two related Penicillium species that produce OTA, were not found in P. thymicola. However, a gene cluster containing a polyketide synthase (PKS) and PKS-nonribosomal peptide synthase (NRPS) hybrid encoding genes were located in the P. thymicola genome that showed a high degree of similarity to OTA biosynthetic enzymes of Aspergillus carbonarius and Aspergillus ochraceus. This is the first report of ochratoxin from P. thymicola and a new record of the species in Canada.

Gastrointestinal Degradation of Fumonisin B₁ by Carboxylesterase FumD Prevents Fumonisin Induced Alteration of Sphingolipid Metabolism in Turkey and Swine

The mycotoxin fumonisin B₁ (FB₁) is a frequent contaminant of feed and causes various adverse health effects in domestic animals. Hence, effective strategies are needed to prevent the impact of fumonisins on livestock productivity. Here we evaluated the capability of the fumonisin carboxylesterase FumD to degrade FB₁ to its less toxic metabolite hydrolyzed FB₁ (HFB₁) in the gastrointestinal tract of turkeys and pigs. First, an ex vivo pig model was used to examine the activity of FumD under digestive conditions. Within 2 h of incubation with FumD, FB₁ was completely degraded to HFB₁ in the duodenum and jejunum, respectively. To test the efficacy of the commercial application of FumD (FUMzyme) in vivo, female turkeys (n = 5) received either basal feed (CON), fumonisin-contaminated feed (15 mg/kg FB₁+FB₂; FB) or fumonisin-contaminated feed supplemented with FUMzyme (15 U/kg; FB+FUMzyme) for 14 days ad libitum. Addition of FUMzyme resulted in significantly decreased levels of FB₁ in excreta, whereas HFB₁ concentrations were significantly increased. Compared to the FB group (0.24 ± 0.02), the mean serum sphinganine-to-sphingosine (Sa/So) ratio was significantly reduced in the FB+FUMzyme group (0.19 ± 0.02), thus resembling values of the CON group (0.16 ± 0.02). Similarly, exposure of piglets (n = 10) to 2 mg/kg FB₁+FB₂ for 42 days caused significantly elevated serum Sa/So ratios (0.39 ± 0.15) compared to the CON group (0.14 ± 0.01). Supplementation with FUMzyme (60 U/kg) resulted in gastrointestinal degradation of FB₁ and unaffected Sa/So ratios (0.16 ± 0.02). Thus, the carboxylesterase FumD represents an effective strategy to detoxify FB₁ in the digestive tract of turkeys and pigs.

Transient endophytic colonizations of plants improve the outcome of foliar applications of mycoinsecticides against chewing insects

The current work reports how spray application of entomopathogenic fungi on alfalfa, tomato and melon plants may cause an additional Spodoptera littoralis larvae mortality due to a temporal colonization of the leaves and subsequent ingestion of those leaves by the larvae. Most entomopathogenic fungi (EF) (Ascomycota: Hypocreales) endophytes seem to colonize their host plants in a non-systemic pattern, in which case at least a transient endophytic establishment of the fungus should be expected in treated areas after spray application. In this work, all strains were able to endophytically colonize roots, stems and leaves during the first 96h after inoculation. Whilst the treatment of S. littoralis larvae with a 10(8)ml(-1) conidial suspension resulted in moderate to high mortality rates for the Metarhizium brunneum EAMb 09/01-Su (41.7-50.0%) and Beauveria bassiana EABb 01/33-Su (66.7-76.6%) strains, respectively, an additive effect was detected when these larvae were also fed endophytically colonized alfalfa, tomato, and melon leaves, with mortality rates varying from 25.0% to 46.7% as a function of the host plant and total mortality rates in the combined treatment of 75-80% and 33-60% for B. bassiana and M. brunneum, respectively. Fungal outgrowth was not detected in any of the dead larvae feeding on colonized leaves, whereas traces of destruxin A were detected in 11% of the insects fed tomato discs endophytically colonized by M. brunneum. The combined effects of the fungal spray with the mortality caused by the feeding of insects on transient EF-colonized leaves have to be considered to estimate the real acute impact of field sprays with entomopathogenic fungi on chewing insects.

Occupational exposure to mould and microbial metabolites during onion sorting--insights into an overlooked workplace

Manual sorting of onions is known to be associated with a bioaerosol exposure. The study aimed to gain an initial indication as to what extent manual sorting of onions is also associated with mycotoxin exposure. Twelve representative samples of outer onion skins from different onion origins were sampled and analyzed with a multimycotoxin method comprising 40 mycotoxins using a single extraction step followed by liquid chromatography with electrospray ionization and triple quadrupole mass spectrometry. Six of the 12 samples were positive for mycotoxins. In those samples, deoxynivalenol, fumonisin B1, and B2 were observed in quantitatively detectable amounts of 3940 ng/g for fumonisin B1 and in the range of 126-587 ng/g for deoxynivalenol and 55-554 ng/g for fumonisin B2. Although the results point to a lower risk due to mycotoxins, the risk should not be completely neglected and has to be considered in the risk assessment.

Evaluation of Microbiological and Chemical Contaminants in Poultry Farms

The aim of the study was to evaluate the microbiological and chemical contamination in settled dust at poultry farms. The scope of research included evaluating the contributions of the various granulometric fractions in settled dust samples, assessing microbial contamination using culture methods, concentrations of secondary metabolites in dust and their cytotoxicity against hepatocyte chicken cells by means of MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) tests. In addition, we also evaluated the concentration of selected volatile odorous compounds (VOCs) using gas chromatographic and spectrophotometric methods and airborne dust concentration in the air with DustTrak™ DRX Aerosol Monitor. Studies were carried out on chicken broilers and laying hens at 13 poultry farms, with numbers of birds ranging from 8000 to 42,000. The airborne total dust concentration at poultry farms averaged 1.44 mg/m³ with a high percentage of the PM10 fraction (particulate matter with a diameter less than 10 μm). Microorganism concentrations in the settled dust were: 3.2 × 10⁸ cfu/g for bacteria and 1.2 × 10⁶ cfu/g for fungi. Potential pathogens (Enterococcus spp., Escherichia coli, Salmonella spp., Aspergillus fumigatus, Paecilomyces variotii) were also found. Secondary metabolites included aurofusarin, deoxynivalenol, 15-hydroxyculmorin zearalenone, zearalenone-sulfate, infectopyron, and neochinulin A. However, the dust samples showed weak cytotoxicity towards chicken hepatocyte cells, which ranged between 9.2% and 29.7%. Among volatile odorous compounds ammonia, acrolein, methyloamine, acetic acid, acetoaldehyde and formaldehyde were detected in the air. In conclusion, settled dust can be a carrier of microorganisms, odours and secondary metabolites in poultry farms, which can be harmful to workers' health.

A new preparative method for simultaneous purification of ochratoxin A and ochratoxin B from wheat culture inoculated with Aspergillus ochraceus

Ochratoxins are a mycotoxin family frequently found in agricultural commodities worldwide and pose a potential health risk to humans and animals. To obtain large amounts of high-purity ochratoxins for food safety monitoring and toxicological research, a novel and effective method was established for simultaneous purification of ochratoxin A (OTA) and ochratoxin B (OTB) from a wheat culture inoculated with an ochratoxin-producing Aspergillus strain. The inoculated wheat culture was first extracted with methanol:water (80:20, v/v), followed by one or two cleanup procedures involving acid-assisted liquid-liquid extraction and gel permeation chromatography. Subsequently, target analytes were separated and collected using preparative high performance liquid chromatography. Finally, a combined approach of ultra-high performance liquid chromatography, ultraviolet spectrophotometry and mass spectrometry was applied for purity analysis and structural identification of the obtained toxins. As a result, 100 g of an inoculated wheat culture yielded 69 mg of OTA and 6 mg of OTB with purities greater than 98%. This proposed method might serve as a valuable reference to obtain expensive ochratoxin standards. To the best of our knowledge, this is the first report on simultaneous preparation of OTA and OTB from artificially inoculated wheat culture.

Familiar Stranger: Ecological Genomics of the Model Saprotroph and Industrial Enzyme Producer Trichoderma reesei Breaks the Stereotypes

The filamentous fungus Trichoderma reesei (Hypocreales, Ascomycota) has properties of an efficient cell factory for protein production that is exploited by the enzyme industry, particularly with respect to cellulase and hemicellulase formation. Under conditions of industrial fermentations it yields more than 100g secreted protein L(-1). Consequently, T. reesei has been intensively studied in the 20th century. Most of these investigations focused on the biochemical characteristics of its cellulases and hemicellulases, on the improvement of their properties by protein engineering, and on enhanced enzyme production by recombinant strategies. However, as the fungus is rare in nature, its ecology remained unknown. The breakthrough in the understanding of the fundamental biology of T. reesei only happened during 2000s-2010s. In this review, we compile the current knowledge on T. reesei ecology, physiology, and genomics to present a holistic view on the natural behavior of the organism. This is not only critical for science-driven further improvement of the biotechnological applications of this fungus, but also renders T. reesei as an attractive model of filamentous fungi with superior saprotrophic abilities.

A green ultrasonic-assisted liquid-liquid microextraction based on deep eutectic solvent for the HPLC-UV determination of ferulic, caffeic and cinnamic acid from olive, almond, sesame and cinnamon oil

A simple, inexpensive and sensitive ultrasonic-assisted liquid-liquid microextraction method based on deep eutectic solvent (UALLME-DES) was used for the extraction of three phenolic acids (ferulic, caffeic and cinnamic) from vegetable oils. In a typical experiment, deep eutectic solvent as green extraction solvent was added to n-hexane (as a typical oil medium) containing target analytes. Subsequently, the extraction was accelerated by sonication. After the extraction, phase separation (DES rich phase/n-hexane phase) was performed by centrifugation. DES rich phase (lower phase) was withdrawn by a micro-syringe and submitted to isocratic reverse-phase HPLC with UV detection. Under optimum conditions obtained by response surface methodology (RSM) and desirability function (DF), the method has good linear calibration ranges (between 1.30 and 1000 µg L(-1)), coefficients of determination (r(2)>0.9949) and low limits of detection (between 0.39 and 0.63 µg L(-1)). This procedure was successfully applied to the determination of target analytes in olive, almond, sesame and cinnamon oil samples. The relative mean recoveries ranged from 94.7% to 104.6%.

A universal multi-wavelength fluorescence polarization immunoassay for multiplexed detection of mycotoxins in maize

Multi-analyte immunoassays have attracted increasing attention due to their short assay times, low sample consumption, and reduced detection costs per assay. In this work, we describe a homologous and high-throughput multi-wavelength fluorescence polarization immunoassay (MWFPIA) for the multiplexed detection of mycotoxins. Three typical Fusarium mycotoxins, deoxynivalenol (DON), T-2 toxin and fumonisin B1 (FB1), were labeled with different dyes. Tracers and specific monoclonal antibodies (mAbs) were employed in the MWFPIA to simultaneously detect the three mycotoxins. Under optimal conditions, the limits of detection using MWFPIA were 242.0 μg kg(-1) for DON, 17.8 μg kg(-1) for T-2 toxin and 331.5 μg kg(-1) for FB1, providing sufficient sensitivity to meet the action levels of these three contaminants in maize as set by the European Union. The use of a methanol/water (2:3, v/v) mixture for sample pretreatment allowed recoveries ranging from 76.5-106.3%, with coefficients of variation less than 21.7%. The total time of analysis, including sample preparation, was less than 30 min. Twenty naturally contaminated maize samples were tested using MWFPIA and HPLC-MS/MS, with correlation coefficients (R(2)) of 0.97 for DON and 0.99 for FB1. By changing the targets of interest, homologous MWFPIA, a method with high sensitivity, a simple procedure and a short analysis time, can easily be extended to other chemical contaminants. Thus, MWFPIA represents a versatile strategy for food safety analysis.

Determination of the Mycotoxin Content in Distiller's Dried Grain with Solubles Using a Multianalyte UHPLC-MS/MS Method

There are more than 300 potential mycotoxins that can contaminate food and feed and cause adverse effects in humans and animals. The data on the co-occurrence of mycotoxins in novel animal feed materials, such as distiller's dried grain with solubles (DDGS), are limited. Thus, a UHPLC-MS/MS method for the quantitation of 77 mycotoxins and other fungal metabolites was used to analyze 169 DDGS samples produced from wheat, maize, and barley and 61 grain samples. All DDGS samples analyzed were contaminated with 13-34 different mycotoxins. Fumonisins were present in all 52 maize DDGS samples (81.0-6890 μg/kg for fumonisin B1), and deoxynivalenol was present in all 99 wheat DDGS samples (39.3-1120 μg/kg). A number of co-occurring mycotoxins were also identified. Due to the high co-occurrence of mycotoxins, routine screening of the animal feed ingredients is highly recommended to allow the highlighted risks to be effectively managed.

Multi-mycotoxin stable isotope dilution LC-MS/MS method for Fusarium toxins in cereals

A multi-mycotoxin stable isotope dilution LC-MS/MS method was developed for 14 Fusarium toxins including modified mycotoxins in cereals (deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, HT2-toxin, T2-toxin, enniatin B, enniatin B1, enniatin A1, enniatin A, beauvericin, fusarenone X, nivalenol, deoxynivalenol-3-glucoside, and zearalenone). The chromatographic separation of the toxins with particular focus on deoxynivalenol and deoxynivalenol-3-glucoside was achieved using a C18-hydrosphere column. An expedient sample preparation method was developed that uses solid-phase extraction for the purification of trichothecenes combined with zearalenone, enniatins, and beauvericin and provides excellent validation data. Linearity, intra-day precision, inter-day precision, and recoveries were ≥0.9982, 1-6%, 5-12%, and 79-117%, respectively. Method accuracy was verified by analyzing certified reference materials for deoxynivalenol, HT2-toxin, and T2-toxin with deviations below 7%. The results of this method found barley malt samples from 2012, 2013, and 2014 frequently contaminated with high concentrations of enniatin B, deoxynivalenol, and its modified mycotoxin deoxynivalenol-3-glucoside. Samples from 2012 were especially contaminated. Fusarenone X was not detected in any of the analyzed samples.

Analytical methods for determination of mycotoxins: An update (2009-2014)

Mycotoxins are a problematic and toxic group of small organic molecules that are produced as secondary metabolites by several fungal species that colonise crops. They lead to contamination at both the field and postharvest stages of food production with a considerable range of foodstuffs affected, from coffee and cereals, to dried fruit and spices. With wide ranging structural diversity of mycotoxins, severe toxic effects caused by these molecules and their high chemical stability the requirement for robust and effective detection methods is clear. This paper builds on our previous review and summarises the most recent advances in this field, in the years 2009-2014 inclusive. This review summarises traditional methods such as chromatographic and immunochemical techniques, as well as newer approaches such as biosensors, and optical techniques which are becoming more prevalent. A section on sampling and sample treatment has been prepared to highlight the importance of this step in the analytical methods. We close with a look at emerging technologies that will bring effective and rapid analysis out of the laboratory and into the field.

Development and validation of an UHPLC-MS/MS method for the determination of mycotoxins in grass silages

An ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) multi-mycotoxin analytical method was developed to simultaneously identify and quantify 20 mycotoxins in grass silages, inclusive of mycotoxins that are currently regulated in European Union feeds. Extraction of mycotoxins from dried grass silages was performed using of a modified QuEChERS extraction employing an acidified aqueous extraction (0.1 N HCl) with no further clean-up. Following chromatographic separation, analytes were detected using a fast polarity-switching MS/MS method that allowed both positive and negative ions to be analysed from a single injection, thus the reducing time and cost of analysis. The limits of detection and quantification ranged between 3 µg kg(-1) DM (aflatoxin B1, beauvericin and enniatin A and A1) and 200 µg kg(-1) DM (deoxynivalenol), and between 10 µg kg(-1) DM (aflatoxin B1, beauvericin and enniatin A1) and 500 µg kg(-1) DM (deoxynivalenol), respectively. Inter-assay accuracy and precision ranged between 90% and 107% and between 3.9% and 15.0% CV, respectively. The accuracy of the method was assessed through the application to a range of incurred samples in an inter-laboratory study.

Tracing the metabolism of HT-2 toxin and T-2 toxin in barley by isotope-assisted untargeted screening and quantitative LC-HRMS analysis

An extensive study of the metabolism of the type A trichothecene mycotoxins HT-2 toxin and T-2 toxin in barley using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) is reported. A recently developed untargeted approach based on stable isotopic labelling, LC-Orbitrap-MS analysis with fast polarity switching and data processing by MetExtract software was combined with targeted LC-Q-TOF-MS(/MS) analysis for metabolite structure elucidation and quantification. In total, 9 HT-2 toxin and 13 T-2 toxin metabolites plus tentative isomers were detected, which were successfully annotated by calculation of elemental formulas and further LC-HRMS/MS measurements as well as partly identified with authentic standards. As a result, glucosylated forms of the toxins, malonylglucosides, and acetyl and feruloyl conjugates were elucidated. Additionally, time courses of metabolite formation and mass balances were established. For absolute quantification of those compounds for which standards were available, the method was validated by determining apparent recovery, signal suppression, or enhancement and extraction recovery. Most importantly, T-2 toxin was rapidly metabolised to HT-2 toxin and for both parent toxins HT-2 toxin-3-O-β-glucoside was identified (confirmed by authentic standard) as the main metabolite, which reached its maximum already 1 day after toxin treatment. Graphical Abstract Isotope-assisted untargeted screening of HT-2 toxin and T-2 toxin metabolites in barley.

Simultaneous Determination of Type A and B Trichothecenes and Their Main Metabolites in Food Animal Tissues by Ultraperformance Liquid Chromatography Coupled with Triple-Quadrupole Mass Spectrometry

A rapid method for the liquid chromatography-tandem mass spectrometric determination of type A and B trichothecenes and their major metabolites in chicken meat, pork, chicken liver, and swine liver was developed. The analytes included T-2 toxin, HT-2 toxin, T-2 triol, neosolaniol, deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, deepoxydeoxynivalenol, and nivalenol. The compounds were extracted from samples with acetonitrile/ethyl acetate (1:3, v/v) and then cleaned up using Oasis HLB cartridges. Analysis was carried out with ultraperformance liquid chromatography-tandem mass spectrometry. The mean recoveries of spiked samples ranged from 74.1% to 96.9% with intraday and interday relative standard deviations of less than 9.9% and 9.1%, respectively. The limit of detection and limit of quantitation ranged from 3.0 to 15.0 μg/kg and from 10.0 to 50.0 μg/kg, respectively. The proposed method has been successfully applied for analysis of real samples, with the primary results indicating that, compared to mycotoxins themselves, their metabolites are more likely to occur and be detectable in animal tissue foods.

A simple sample pretreatment method for multi-mycotoxin determination in eggs by liquid chromatography tandem mass spectrometry

In this study, a reliable and fast method using a quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction procedure without any clean-up step was developed for simultaneous extraction of 15 mycotoxins, i.e., aflatoxin B1, aflatoxin B2, aflatoxin G1, aflatoxin G2, aflatoxin M1, aflatoxin M2, deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, de-epoxy-DON, zearalenone, α-zearalenol, β-zearalenol, α-zearalanol, and β-zearalanol, from eggs. High-performance liquid chromatography tandem mass spectrometry was used to separate and detect all of the analytes. Electrospray ionization at both negative and positive modes and multiple reaction-monitoring mode were applied to detect these analytes. The main factors, such as extraction time, extraction solvent, evaporation temperature, and pH of the solvent, were carefully optimized to improve the extraction efficiency. The coefficients of determination of the calibration curves ranged from 0.9884 to 0.9998. The recoveries of most of the analytes were between 71.3% and 105.4% at three concentration levels, except for AFB1 that showed recovery rates of not more than 67.5% in all concentrations. The repeatability and intra-lab reproducibility of this method were both lower than 15% and 25%, respectively. The limit of quantification ranged from 0.2 μg/kg to 5 μg/kg. The matrix effect was evaluated and reduced by the use of matrix-matched calibration curves. The validated method was applied in a pilot study to analyze mycotoxin contamination in 12 eggs, and trace amounts of deoxynivalenol, 15-acetyldeoxynivalenol, aflatoxin B1, aflatoxin G2, zearalenone and β-zearalenol were detected in these samples.