Reduce Mycotoxin Contamination Research Articles

Dietary exposure of school children to aflatoxin and fumonisin through githeri and effectiveness of nixtamalization in reduction of these toxins in githeri from Turkana County.

Exposure of school children to aflatoxin and fumonisin is mainly through diet. In Kenyan public schools, children are given porridge made from maize flour for breakfast, a mixture of maize and beans, also known as githeri for lunch and ugali for dinner. Nixtamalization has proved to reduce mycotoxins in most cereals and not a mixture of maize and beans. This study, therefore, aimed to assess the exposure of primary school children in Turkana County to aflatoxin and fumonisin through maize-based food under the school meals program and the effectiveness of nixtamalization in the reduction of these mycotoxins. Samples of githeri were randomly collected from all public primary schools (n = 128) under the homegrown school meals program in Turkana County and analyzed for aflatoxin and fumonisin. The data was analyzed using SAS software, version 9.4. The deterministic model was used to calculate the estimated daily intake (EDI) and the margin of exposure (MOE) used to characterize the exposure risk. The contaminated samples were then treated with various concentrations of Ca(OH)2, 0.5-2.5%. The treated samples were cooked for 60 and 75min and soaked for 6 and 8h. Forty percent of the schools contained githeri samples with aflatoxin B1 levels above 5µg/Kg, the maximum limit for Kenya. Exposure to aflatoxin B1 and total aflatoxin was up to 2µg/kg/bw/day. The range for fumonisin exposure was 60-80µg/kg/bw/day. Ca(OH)2 concentration levels of up to 2.5% reduced aflatoxin by 75% and fumonisin by 72%. The findings indicate that githeri is contaminated with aflatoxin and fumonisin which exposes school children to these mycotoxins and nixtamalization can be used to reduce mycotoxin contamination in githeri.

Molecular Identification and Antifungal Activity of Candida chrysomelidarum and Rhodotorula toruloides Isolated from Indonesian Indigenous Fruit Flacourtia inermis Roxb. (Lobi-lobi) against Pathogenic Mold Aspergillus flavus

Aspergillus flavus is one of the main contaminating mold species in most feed products, significantly impacting human and animal health. This study aims to isolate the epiphytic yeasts from the fruit Flacourtia inermis Roxb and test their potential ability to act as biocontrol agents for A. flavus. The antagonistic test was performed using a dual culture method, and the potential yeast isolates were then identified using a combination of morphology characterization and molecular sequence analysis. From 42 yeast isolated from F. inermis fruit, 2 yeast isolates (LCA 75 and LCA 102) demonstrated the highest inhibition growth against A. flavus (32.32 and 32.30 %, respectively). The isolates LCA 75 and LCA 102 were identified as Candida chrysomelidarum and Rhodotorula toruloides, respectively. Rhodotorula toruloides, identified as one of the yeast isolates (LCA 102), is an unconventional red yeast demonstrating notable antagonistic effects against A. flavus, inhibiting its growth by 32.30 %. This yeast, also known as Rhodosporidium toruloides, R. rubescens, R. glutinis, or R. gracilis, belongs to the subphylum Pucciniomycotina within the division Basidiomycota. The significant inhibition of mycelium growth and sporulation observed in our study highlights the potential of R. toruloides, along with C. chrysomelidarum (LCA 75), as effective biocontrol agents to reduce mycotoxin contamination in chicken feed by A. flavus. This study represents a significant advancement in the management of A. flavus contamination in animal feed. The findings not only underscore the viability of yeast-based biocontrol strategies but also contribute to a safer, more sustainable approach to preventing mycotoxin proliferation in feedstocks. HIGHLIGHTS Founding Out of 42 yeast isolates, two (LCA 75 and LCA 102) demonstrated the highest inhibition growth against A. flavus, with inhibition rates of 32.32 and 32.30 %, respectively. Identified Yeasts: LCA 75 as Candida chrysomelidarum LCA 102 as Rhodotorula toruloides (alternatively referred to as Rhodosporidium toruloides, R. rubescens, R. glutinis, or R. gracilis). Characteristics of Rhodotorula toruloides Unconventional red yeast belonging to the subphylum Pucciniomycotina within Basidiomycota. Commonly associated with various plant species and found on plant surfaces, including leaves, stems, and fruits. Identified yeast isolates exhibited inhibition activities leading to reduced mycelium growth and sporulation of A. flavus. These yeast isolates have potential as biocontrol agents to prevent mycotoxin contamination in chicken feed caused by A. flavus. GRAPHICAL ABSTRACT

Farmers’ willingness to adopt precision agricultural technologies to reduce mycotoxin contamination in grain: evidence from grain farmers in Spain and Lithuania

PurposeThis study examines the willingness of Spanish and Lithuanian grain farmers to adopt a combined approach of preventive site-specific spraying (PSSS) and selective harvesting (SH), two precision agricultural technologies (below referred to as PSSS-SH) aimed at mitigating the risk of mycotoxin contamination in barley and wheat.MethodsData were collected from 190 commercial grain farmers using a choice experimental survey. The empirical analysis relied on the estimation of mixed logit and integrated latent class models.ResultsThe surveyed farmers were heterogeneous in their preference for the PSSS-SH technology, with a majority (81%) reporting that they were willing to adopt and pay for the PSSS-SH technology. Furthermore, the farmers’ willingness to adopt PSSS-SH technology was influenced by the trade-offs between the potential production, economic and environmental changes.ConclusionProfit maximization is not the only motivation for a farmer’s decision to adopt PSSS-SH, there are also important non-financial benefits that align with the observed choices. Furthermore, the perceived usefulness of the technology, the willingness and readiness to use the technology, and the farmer characteristics (e.g. cooperative membership, employment status, share of household income from grain production and past experience with precision farming technology) were positively associated with uptake of the PSSS-SH technology. Therefore, extension programmes should have a special focus on the perceived usefulness of the technology, the willingness and readiness of farmers to use it, and its unique characteristics.

Association between spectrum of mycotoxins and semen quality: A cross-sectional study in Beijing, China

Exposure to mycotoxins is unavoidable in daily life through ingestion, dermal, and inhalation routes. Toxicological studies found that exposure to mycotoxins might affect male reproductive function. However, there is still a lack of population evidence. We aimed to assess the association of individual and joint exposure to spectrum of mycotoxins with semen quality. The present study included 192 participants in Beijing, China. We measured conventional semen parameters and assessed semen quality. Sixty-seven traditional or emerging mycotoxins were determined to describe the spectrum of mycotoxins. The participants were widely exposed to multiple mycotoxins, and nearly half were simultaneously exposed to more than six mycotoxins. After adjusting potential confounders, logistic regression indicated that the number and concentration of plasma mycotoxin were correlated to the risk of low semen quality. Plasma beauvericin and citrinin concentrations were associated with lower semen quality. The least absolute shrinkage and selection operator regression showed similar results to logistic regression. Quantile-based g-computation and Bayesian kernel machine regression models found that the mixture of mycotoxins was harmful to semen quality, especially in sperm motility. In conclusion, both individual and mixture of mycotoxin exposure were correlated with lower semen quality. More regulations and measures should be taken to reduce mycotoxin contamination.

Exploring the influence of wood ash, maize cob ash, and tequesquite (alkaline rock) on nixtamalization of maize

Nixtamalization, an ancient process vital for maize processing, enhances maize's nutritional value, texture, flavor, and shelf life while reducing mycotoxin contamination, making it a cornerstone technique in maize processing with both nutritional and food safety implications. Initially performed with ashes, modern nixtamalization relies on food-grade calcium hydroxide or calcium oxide (lime). However, regions lacking lime deposits or processing technology necessitate alternative nixtamalization options for sustainable maize processing. This study aimed to assess the mineral composition of alkaline rocks (tequesquite) and two types of ash (wood and maize cob) and determine the optimal cooking conditions to achieve tortillas comparable to those made from lime-nixtamalized maize. Different ash and tequesquite concentrations (5%, 10%, and 15%) were tested with nixtamalization durations of 40, 50, and 60 min. Quality parameters of nixtamal and tortillas were evaluated. Data were analyzed using a completely randomized design with Tukey's comparison of means (p ≤ 0.05) and principal components analysis. Results revealed potassium as the predominant element in the ash, while sodium prevailed in tequesquite. Although significant differences were observed in nixtamalization variables, tortillas made with 5% maize cob ash or tequesquite closely resembled those treated with lime in terms of quality parameters.

Development of an Efficient CRISPR/Cas9 System in Fusarium verticillioides and Its Application in Reducing Mycotoxin Contamination.

Fusarium verticillioides (F. verticillioides) is a globally recognized and highly impactful fungal pathogen of maize, causing yield losses and producing harmful mycotoxins that pose a threat to human and animal health. However, the genetic tools available for studying this crucial fungus are currently limited in comparison to other important fungal pathogens. To address this, an efficient CRISPR/Cas9 genome editing system based on an autonomously replicating plasmid with an AMA1 sequence was established in this study. First, gene disruption of pyrG and pyrE via nonhomologous end-joining (NHEJ) pathway was successfully achieved, with efficiency ranging from 66 to 100%. Second, precise gene deletions were achieved with remarkable efficiency using a dual sgRNA expression strategy. Third, the developed genome editing system can be applied to generate designer chromosomes in F. verticillioides, as evidenced by the deletion of a crucial 38 kb fragment required for fumonisin biosynthesis. Fourth, the pyrG recycling system has been established and successfully applied in F. verticillioides. Lastly, the developed ΔFUM1 and ΔFUM mutants can serve as biocontrol agents to reduce the fumonisin B1 (FB1) contamination produced by the toxigenic strain. Taken together, these significant advancements in genetic manipulation and biocontrol strategies provide valuable tools for studying and mitigating the impact of F. verticillioides on maize crops.

Emerging Alternaria toxins present in naturally contaminated dried tomatoes and their reduction using cold atmospheric plasma

This study investigated the efficacy of cold atmospheric plasma (CAP) treatment in degrading the emerging Alternaria toxins as pure molecules and as natural contaminants in dried tomatoes. The analyses of 25 batches of dried tomatoes showed that more than 40% of samples were contaminated with tenuazonic acid (TeA), one with Alternariol (AOH), while Tentoxin (TEN), Alternariol monomethyl ether (AME) and Altenuene (ALT) were not detected. CAP under ozone (O3) and NOx regimes were used to reduce the mycotoxin contamination, the results shown that O3 regime was more effective against all mycotoxins tested, while NOx regime showed different efficacy depending on the specific mycotoxin. The Weibull model proved to be appropriate for the degradation kinetics of all Alternaria toxins, regardless of the kinetic order they possess. Under the O3 regime, the resistance of the mycotoxin was AME > AOH > TEN > TeA > ALT. Our studies have shown for the first time that CAP reduces Alternaria toxins in naturally contaminated dried tomatoes. In particular, the rate of degradation under O3 regime increased significantly with the longest exposure time, reaching 52.80 ± 1.21 % of mycotoxin degradation. Our results expand our knowledge of CAP treatment as a potential means of reducing mycotoxin contamination in food. Further studies will be carried out to investigate the potential mycotoxin degradation products and to ensure food safety.

Determination of Mycotoxins in Plant-Based Meat Alternatives (PBMAs) and Ingredients after Microwave Cooking.

In this study, we investigate the role of microwave cooking in reducing mycotoxin contamination in plant-based food matrices, with a focus on veggie burgers (purchased and home-made) and their ingredients (soybean, potatoes, zucchini, carrots). Two different conditions were studied (Max-Min) that were 800 W for 60 s and 800 W for 90 s, respectively. The degradation patterns of aflatoxins (AFB1, AFB2, AFG1, AFG2), fumonisins (FB1, FB2, FB3), trichothecenes (T2, HT2, ZEA), and ochratoxin A (OTA) were studied. The extraction procedures were conducted with the QuEChERS extraction, and the analyses were conducted with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Principal component analysis (PCA) showed that degradation under microwave cooking varies considerably across different food matrices and cooking conditions. This study provides valuable insights into the degradation of mycotoxins during microwave cooking and underscores the need for more research in this area to ensure food safety.

Mycotoxin reduction and metabolite profiles of ogi produced using traditional fermentation methods

Mycotoxins are widely present in maize, a favourite staple food in sub-Saharan Africa. Food processing methods, like fermentation, have been suggested as potential ways to reduce mycotoxin contamination levels in the grain and, as a result, limit the exposure of crop consumers to the harmful effects of the toxins. The influence of four traditional fermentation processes [cold (with changed steeping liquor (CSL) and unchanged steeping liquor (USL), Fon and Goun procedures] on the mycotoxin reduction and metabolites profile of ogi, a fermented maize product, was studied. Ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) and gas chromatography linked to high resolution time-of-flight mass spectrometry (GC-HR-TOF-MS) were respectively employed for the mycotoxin and metabolite profiles analyses of the samples. Among the nine mycotoxins detected in the raw maize samples, aflatoxin B1 (AFB1) and fumonisin B1 (FB1) + fumonisin B2 (FB2) concentrations were found to exceed the European Union (EU) maximum limit. Both cold (containing USL and CSL) and Goun fermentation techniques were able to lower the AFB1 concentration below this threshold. The metabolomics result revealed that ogi produced using the cold (USL) and Fon fermentation processes had the highest number of most of the detected important compounds, whereas the Goun fermentation process produced the fewest compounds in total. There was no statistically significant difference in the ability of the specified natural fermentation processes to lower FB1, FB2, FB3, deoxynivalenol (DON), sterigmatocystin (STERIG), and zearalenone concentrations in maize (ZEN). In addition, the results demonstrated that the four natural fermentation processes evaluated had varying effects.

Presence, Co-Occurrence, and Daily Intake Estimates of Aflatoxins and Fumonisins in Maize Consumed in Food-Insecure Regions of Western Honduras.

Foodborne mycotoxins are a significant food safety risk in developing countries. Our objective was to determine the occurrence of and exposure levels to aflatoxins (AFs) and fumonisins (FBs) in maize intended for human and animal consumption in food-insecure regions of western Honduras. Total AFs and FBs were quantified with a monoclonal antibody-based affinity spectrofluorimetric method. FBs were detected in 614/631 samples of maize destined for human consumption at 0.3 to 41 mg/kg (mean, 2.7 mg/kg). Of the 614 positive samples, 147 had FB levels exceeding the U.S. Food and Drug Administration (FDA) advisory threshold of 4.0 mg/kg. AFs were detected in 109/631 samples of maize for human consumption with concentrations between 1.0 and 490 µg/kg (mean, 10 µg/kg). AF levels in 34 samples exceeded the FDA regulatory limit (i.e., 20 µg/kg). The average probable daily intake of AFs in western Honduras ranged from 0 to 260 ng/kg body weight/day, and for FBs, the average probable daily intake ranged from 17 to 53 μg/kg body weight/day. AFs and FBs co-occurred in 106/631 samples with 60 samples containing both toxins at levels greater than the FDA regulatory levels. Samples of maize intended for animal feed had significantly higher AF (mean, 22 µg/kg) and FB (mean, 7.6 mg/kg) contamination levels than those observed in samples destined for human consumption. Thus, the maize supply chain in western Honduras is contaminated with mycotoxins at levels that pose health risks to both humans and livestock. More effective mycotoxin surveillance and implementation of effective mitigation strategies are needed to reduce mycotoxin contamination and exposure.

Simultaneous degradation of aflatoxin B1 and zearalenone by Porin and Peroxiredoxin enzymes cloned from Acinetobacter nosocomialis Y1

Mycotoxin contamination can cause severe health issues for both humans and animals. This study examined the potential of enzymes derived from Acinetobacter nosocomialis Y1 to simultaneously degrade aflatoxin B1 (AFB1) and zearalenone (ZEN), which could have significant implications in reducing mycotoxin contamination. Two enzymes, Porin and Peroxiredoxin, were identified with molecular weights of 27.8 and 20.8 kDa, respectively. Porin could completely degrade 2 µg/mL of AFB1 and ZEN within 24 h at 80 °C and 60 °C, respectively. Peroxiredoxin could completely degrade 2 µg/mL of AFB1 and reduce ZEN by 91.12% within 24 h. The addition of Na+, Cu2+, and K+ ions enhanced the degradation activities of both enzymes. LC-MS/MS analysis revealed that the molar masses of the degradation products of AFB1 and ZEN were 286 g/mol and 322.06 g/mol, and the products were identified as AFD1 and α or β-ZAL, respectively. Vibrio fischeri bioluminescence assays further confirmed that the cytotoxicity of the two degradation products was significantly lower than that of AFB1 and ZEN. Based on these results, it can be inferred that the degradation product of ZEN is β-ZAL. These findings suggest that both enzymes have the potential to be utilized as detoxification enzymes in food and feed.

Effect of Fungicide Treatment on Multi-Mycotoxin Occurrence in French Wheat during a 4-Year Period

Wheat represents one of the most widely consumed cereals worldwide. Cultivated in winter and spring, it is vulnerable to an array of different pathogens, including fungi, which are managed largely through the in-field application of fungicides. During this study, a 4-year field investigation (2018–2021) was performed in France, aiming to assess the efficacy of fungicide treatment to reduce mycotoxin contamination in common and durum wheat. Several different commercially available fungicides were applied via sprayers. Concentrations of mycotoxins and fungal metabolites in wheat were determined using a multi-analyte liquid-chromatography–tandem-mass-spectrometry-based method. The highest contamination levels and strongest effects of fungicides were observed in 2018, followed by 2021. A significant fungicide-mediated reduction was observed for the trichothecenes deoxynivalenol, deoxynivalenol-3-glucoside, nivalenol, and nivalenol-3-glucoside. Furthermore, fungicide treatment also reduced levels of culmorin and its hydroxy metabolites 5- and 15-hydroxy-culmorin, as well as aurofusarin. Interestingly, the Alternaria metabolite infectopyron was increased following fungicide treatment. In conclusion, fungicide treatment was effective in reducing mycotoxin levels in wheat. However, as complete prevention of mycotoxin contamination was not achieved, fungicide treatment should always be combined with other pre- and post-harvest mycotoxin mitigation strategies to improve food and feed safety.

Enhancement of agri-food by-products: green extractions of bioactive molecules with fungicidal action against mycotoxigenic fungi and their mycotoxins.

Today, alternative strategies based on the use of bioactive compounds have been proposed to reduce mycotoxin contamination and limit the use of chemical fungicides. In the present work, several by-products collected from the agri-food chain (i.e., red and white grape marc, red grapevine leaves, grape seeds and stalks, pear, apple, green beans, tomato, and spent hops) were subjected to green extraction protocols (i.e., steam distillation, Ultrasound-Assisted, and Naviglio® extraction) to obtain extracts rich in polyphenols and terpenes. Each extract was assessed in vitro for its ability to inhibit the development of the main mycotoxigenic species and related mycotoxins. Aspergillus flavus and A. carbonarius were significantly reduced by pear (from -45 to -47%) and grape marc (from -21 to -51%) extracts, while F. graminearum was shown to be highly influenced by grape stalk, pear, and grape marc extracts (-24% on average). On the contrary, F. verticillioides was inhibited only by pear (-18%) and to a very low and negligible extent by apple (-1%) and green beans (-3%). Regarding the reduction of mycotoxins, the extracts were able to inhibit OTA from 2 to 57%, AFB1 from 5 to 75%, and DON from 14 to 72%. The highest percentages of reduction were obtained against FBs (from 11 to 94%), ZEN (from 17 to 100%), and Alternaria toxins (from 7 to 96%). In conclusion, this work provided promising results for the production of bioactive extracts obtained from agri-food by-products, which could be exploited as potential biofungicides against the development of mycotoxigenic fungi and related mycotoxins.

Combined toxicity assessment of a naturally occurring toxin and a triazole fungicide on different biological processes through toxicogenomic data mining with mixtures

Fungicides are widely used to prevent fungal growth and reduce mycotoxin contamination in food, which provides the opportunity for the co-occurrence of mycotoxins and fungicide residues in food and poses a greater risk to human health. To assess the combined effects of a naturally occurring mycotoxin, citrinin (CIT), and a widely used triazole fungicide, triadimefon (TAD) on different biological processes, the comparative toxicogenomics database was used to obtain phenotypes and response genes for CIT or TAD exposure. Then individual and combined exposure models were developed with zebrafish embryos, and the interaction between CIT and TAD was analyzed using the 2 × 2 factorial design approach to observe the toxic effects. Through data mining analysis, our results showed that CIT or TAD exposure is related to different biological phenotypes, such as cell death, regulation of antioxidant systems, and thyroid hormone metabolism. Our results also showed that CIT (4-day LC50 value of 12.7 mg/L) exposure possessed higher toxicity to zebrafish embryos compared with TAD (4-day LC50 value of 29.6 mg/L). Meanwhile, individual exposure to CIT and TAD altered the expression levels of biomarkers related to oxidative stress, inflammation, apoptosis and hypothalamic-pituitary-thyroid (HPT) axis. Notably, combined exposure to CIT and TAD induced changes in the mentioned biological processes and had an interactive effect on the expression of multiple biomarkers. In conclusion, we evaluated the toxic effects of CIT and TAD in isolation and combination by in-vivo experiments, which provide a new methodological basis and reference for future risk assessment and setting of safety limits for foodborne toxicants.

Mycological and Multiple Mycotoxin Surveillance of Sorghum and Pearl Millet Produced by Smallholder Farmers in Namibia

Mycological (mycotoxigenic Fusarium and aflatoxigenic Aspergillus spp.) and multiple mycotoxins [aflatoxin B1 (AFB1), fumonisin B (FB), deoxynivalenol and zearalenone] surveillance was conducted on raw whole grain sorghum (Sorghum bicolor) and pearl millet (Pennisetum glaucum) produced on smallholder farms, and processed products sold at open markets in northern Namibia. Fungal contamination was determined with morphological methods as well as with quantitative Real-Time PCR (qPCR). The concentrations of multiple mycotoxins in samples were determined with liquid chromatography tandem mass spectrometry. The incidence of mycotoxigenic Fusarium spp., Aspergillus flavus and A. parasiticus, as well as the concentrations of AFB1 and FB were significantly (P < 0.001) higher in the malts as compared to the raw whole grains, with Aspergillus spp. and AFB1 exhibiting the highest contamination (P < 0.001). None of the analysed mycotoxins were detected in the raw whole grains. Aflatoxin B1 above the regulatory maximum level set by the European Commission was detected in sorghum (2 of 10 samples; 20%; 3–11 µg/kg) and pearl millet (6 of 11 samples; 55%; 4–14 µg/kg) malts. Low levels of FB1 (6 of 10 samples; 60%; 15–245 µg/kg) were detected in sorghum malts and no FB was detected in pearl millet malts. Contamination possibly occurred postharvest, during storage, and/or transportation and processing. By critically monitoring the complete production process, the sources of contamination and critical control points could be identified and managed. Mycotoxin awareness and sustainable education will contribute to reducing mycotoxin contamination. This could ultimately contribute to food safety and security in northern Namibia where communities are exposed to carcinogenic mycotoxins in their staple diet.

Multi-mycotoxins analysis in post-harvest maize (Zea mays L.) grain from major producing areas of Ethiopia

Mycotoxins are the most notorious compounds contaminating food crops in the production chains, in which cereals and nuts are primarily infected. The present study was aimed at determining multi-mycotoxins in maize grain samples collected at post-harvest stages across the main maize producing districts of Ethiopia. Then, 80 maize samples were collected from three districts (Bako, Ilu Gelan and Oda Bultum) and were analysed by LC-MS/MS. A total of 114 metabolites were withPenicillium andAspergillus metabolites being positively identified in 26.3 and 18.4% of the samples, respectively. Among the mycotoxins addressed by regulatory limits, deoxynivalenol was detected in 85% of samples with the maximum level of 2,530 μg/kg, while zearalenone was detected in 81%, with levels as high as 3,750 μg/kg. A marked difference was observed across the study locations in the study areas, in which significant difference (P&lt;0.005) of mycotoxin contamination recorded. For instances, of the total sample, contamination was detected on 78.1% in Oda Bultum followed by Ilu Gelan which was detected on 73.7% of the total samples with less proportion of contaminated from Bako district (68.4%). Different mycotoxins of regulated, binding or masked and emerging mycotoxin were also simultaneously detected in the samples. Intervention strategies which can reduce mycotoxin contamination along the maize value chains are required to combat the mycotoxin problems. Further, multi-season studies over multiple agro-ecologies are suggested for the county.

Inhibitory effect of (E)-2-heptenal on Aspergillus flavus growth revealed by metabolomics and biochemical analyses

The prevention of fungal proliferation in postharvest grains is critical for maintaining grain quality and reducing mycotoxin contamination. Fumigation with natural gaseous fungicides is a promising and sustainable approach to protect grains from fungal spoilage. In this study, the antifungal activities of (E)-2-alkenals (C5-C10) on Aspergillus flavus were tested in the vapor phase, and (E)-2-heptenal showed the highest antifungal activity against A. flavus. (E)-2-Heptenal completely inhibited A. flavus growth at 0.0125 µL/mL and 0.2 µL/mL in the vapor phase and liquid contact, respectively. (E)-2-Heptenal can disrupt the plasma membrane integrity of A. flavus via leakage of intracellular electrolytes. Scanning electron microscopy indicated that the mycelial morphology of A. flavus was remarkably affected by (E)-2-heptenal. Metabolomic analyses indicated that 49 metabolites were significantly differentially expressed in A. flavus mycelia exposed to 0.2 µL/mL (E)-2-heptenal; these metabolites were mainly involved in galactose metabolism, starch and sucrose metabolism, the phosphotransferase system, and ATP-binding cassette transporters. ATP production was reduced in (E)-2-heptenal-treated A. flavus, and Janus Green B staining showed reduced cytochrome c oxidase activity. (E)-2-Heptenal treatment induced oxidative stress in A. flavus mycelia with an accumulation of superoxide anions and hydrogen peroxide and increased activities of superoxide dismutase and catalase. Simulated storage experiments showed that fumigation with 400 µL/L of (E)-2-heptenal vapor could completely inhibit A. flavus growth in wheat grains with 20% moisture; this demonstrates its potential use in preventing grain spoilage. This study provides valuable insights into understanding the antifungal effects of (E)-2-heptenal on A. flavus. KEY POINTS : • (E)-2-Heptenal vapor showed the highest antifungal activity against A. flavus among (C5-C10) (E)-2-alkenals. • The antifungal effects of (E)-2-heptenal against A. flavus were determined. • The antifungal actions of (E)-2-heptenal on A. flavus were revealed by metabolomics and biochemical analyses.

Harvest and post-harvest handling practices associated with fumonisin B1 contamination in maize (Zea mays L.): dietary exposure and risk characterization in eastern Ethiopia.

Maize is the main staple food crop in the eastern part of Ethiopia. However, maize loss is a major issue due to fungal contamination especially at the post-harvest stage owing to inadequate handling practices. This study aimed to assess post-harvest handling and awareness against fungal development and fumonisin B1 (FB1) in maize and to calculate risk exposures of FB1. A total of 197 maize samples (grain and flour) were collected from five districts (Haramaya, Kersa, Meta, Oda Bultum, and Tullo). FB1 was detected using LC-MS/MS qTRAP. Exposure assessment was done based on the maize consumption rate per day in Ethiopia for different age groups (infants, children, and adults). Risk characterization depends on the margin of exposure (MoE) combined with the lower confidence limit of the benchmark dose level (BMDL). About 81% of farmers were not physically separating undamaged maize ears with damaged from either birds or fungi. Moreover, 100% were not using improved storage material. In storage samples, FB1 was detected as high as 1058μg/kg ± 234 in the Kersa district while a minimum of 22.60μg/kg ± 5.27 in Meta. In flour samples, the maximum FB1 (327μg/kg) was detected from the Oda Bultum district. The maximum exposure of infants was estimated at Kersa (1131µg/kg bw/day), followed by Oda Bultum (1073µg/kg bw/day) and Haramaya (854µg/kg bw/day). Overall, FB1 exposures ranged from 6.09 to 1131µg/kg bw/day, which is 3 to 500µg/kg bw/day higher than the maximum tolerable daily intake of 2µg/kg bw/day recommended by the World Health Organization. The MoE ranged from 0.15 to 176, with infants being at higher risk than adults. The study highlights the urgent need to enhance growers' awareness and knowledge of good post-harvest practices to reduce mycotoxin contamination in maize. Further biomarker analysis must be pursued to determine the risk exposure assessment for different age groups in these areas with a priority for the Kersa district.

Elimination of Deoxynivalenol, Aflatoxin B1, and Zearalenone by Gram-Positive Microbes (Firmicutes).

Mycotoxin contaminations in the feed and food chain are common. Either directly or indirectly, mycotoxins enter the human body through the consumption of food of plant and animal origin. Bacteria with a high mycotoxin elimination capability can reduce mycotoxin contamination in feed and food. Four Gram-positive endospore-forming bacteria (Bacillus thuringiensis AMK10/1, Lysinibacillus boronitolerans AMK9/1, Lysinibacillus fusiformis AMK10/2, and Rummeliibacillus suwonensis AMK9/2) were isolated from fermented forages and tested for their deoxynivalenol (DON), aflatoxin B1 (AFB1), and zearalenone (ZEA) elimination potentials. Notably, the contribution of bacterial cell wall fractions to the observed outstanding ZEA elimination rates was demonstrated; however, the ZEA elimination differed considerably within the tested group of Gram-positive bacteria. It is worth noting that the purified cell wall of L. boronitolerans AMK9/1, L. fusiformis AMK10/2 and B. thuringiensis AMK10/1 were highly efficient in eliminating ZEA and the teichoic acid fractions of B. thuringiensis AMK10/1, and L. fusiformis AMK10/2 could also be successfully used in ZEA binding. The ZEA elimination capacity of viable R. suwonensis AMK9/2 cells was outstanding (40%). Meanwhile, R. suwonensis AMK9/2 and L. boronitolerans AMK9/1 cells produced significant esterase activities, and ZEA elimination of the cell wall fractions of that species did not correlate with esterase activity. DON and AFB1 binding capabilities of the tested bacterial cells and their cell wall fractions were low, except for B. thuringiensis AMK10/1, where the observed high 64% AFB1 elimination could be linked to the surface layer (S-layer) fraction of the cell wall.

Transcriptomic Response of Fusarium verticillioides to Variably Inhibitory Environmental Isolates of Streptomyces.

Fusarium verticillioides is a mycotoxigenic fungus that is a threat to food and feed safety due to its common infection of maize, a global staple crop. A proposed strategy to combat this threat is the use of biological control bacteria that can inhibit the fungus and reduce mycotoxin contamination. In this study, the effect of multiple environmental isolates of Streptomyces on F. verticillioides was examined via transcriptome analysis. The Streptomyces strains ranged from inducing no visible response to dramatic growth inhibition. Transcriptionally, F. verticillioides responded proportionally to strain inhibition with either little to no transcript changes to thousands of genes being differentially expressed. Expression changes in multiple F. verticillioides putative secondary metabolite gene clusters was observed. Interestingly, genes involved in the fusaric acid gene cluster were suppressed by inhibitory strains of Streptomyces. A F. verticillioides beta-lactamase encoding gene (FVEG_13172) was found to be highly induced by specific inhibitory Streptomyces strains and its deletion increased visible response to those strains. This study demonstrates that F. verticillioides does not have an all or nothing response to bacteria it encounters but rather a measured response that is strain specific and proportional to the strength of inhibition.