Browsing by Author "Garcia-Cela, Esther"
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Item Open Access Biological control products for aflatoxin prevention in Italy: Commercial field evaluation of atoxigenic Aspergillus flavus active ingredients(MDPI, 2018-01-05) Mauro, Antonio; Garcia-Cela, Esther; Pietri, Amedeo; Cotty, Peter J.; Battilani, PaolaSince 2003, non-compliant aflatoxin concentrations have been detected in maize produced in Italy. The most successful worldwide experiments in aflatoxin prevention resulted from distribution of atoxigenic strains of Aspergillus flavus to displace aflatoxin-producers during crop development. The displacement results in lower aflatoxin concentrations in harvested grain. The current study evaluated in field performances of two atoxigenic strains of A. flavus endemic to Italy in artificially inoculated maize ears and in naturally contaminated maize. Co-inoculation of atoxigenic strains with aflatoxin producers resulted in highly significant reductions in aflatoxin concentrations (>90%) in both years only with atoxigenic strain A2085. The average percent reduction in aflatoxin B1 concentration in naturally contaminated maize fields was 92.3%, without significant differences in fumonisins between treated and control maize. The vegetative compatibility group of A2085 was the most frequently recovered A. flavus in both treated and control plots (average 61.9% and 53.5% of the A. flavus, respectively). A2085 was therefore selected as an active ingredient for biocontrol products and deposited under provisions of the Budapest Treaty in the Belgian Co-Ordinated Collections of Micro-Organisms (BCCM/MUCL) collection (accession MUCL54911). Further work on development of A2085 as a tool for preventing aflatoxin contamination in maize produced in Italy is ongoing with the commercial product named AF-X1™.Item Open Access Data underpinning "Water and temperature relations of Fusarium langsethiae strains and modelling of growth and T-2 and HT-2 mycotoxin production on oat-based matrices"(Cranfield University, 2021-04-23 11:55) Verheecke, Carol; Garcia-Cela, Esther; Lopez-Prietro, Alejandro; Osk Jonsdottir, Inga; Medina Vaya, Angel; Magan, NareshThese data are linked to the paper Water and temperature relations of Fusarium langsethiae strains and modelling of growth and T-2 and HT-2 mycotoxin production on oat-based matrices.Item Open Access Fungal diversity and metabolomic profiles in GM and isogenic non-GM maize cultivars from Brazil(Springer, 2020-10-12) Gasperini, A. M.; Garcia-Cela, Esther; Sulyok, M.; Medina, Angel; Magan, NareshThere is little knowledge of the microbial diversity, mycotoxins and associated secondary metabolites in GM maize and isogenic non-GM cultivars (cvs). This study has quantified the microbial populations and dominant fungal genera in 6 cvs of each type representative of herbicide, pesticide or stacked resistance to both. The predominant mycotoxins and targeted metabolomics profiles were also compared between the two sets of cvs. This showed that the overall fungal populations were 8.8 CFUs g−1 maize. The dominant genera, isolated from maize samples, whether surface-sterilised or not, in all maize cvs were Fusarium, followed by Penicillium, Aspergillus and occasionally Cladosporium and Alternaria. The analysis of the targeted metabolomics showed that approx. 29 different metabolites were detected. These were dominated by fumonisins and minor Penicillium spp. metabolites (questiomycin A and rugulovasine A). Interestingly, the range and number of mycotoxins present in the GM cvs were significantly lower than in the non-GM maize samples. This suggests that while the fungal diversity of the two types of maize appeared to be very similar, the major contaminant mycotoxins and range of toxic secondary metabolites were much lower in the GM cvs.Item Open Access Fusarium graminearum in stored wheat: use of CO2 production to quantify dry matter losses and relate this to relative risks of Zearalenone contamination under interacting environmental conditions(MDPI, 2018-02-17) Garcia-Cela, Esther; Kiaitsi, Elisavet; Sulyok, Michael; Medina-Vayá, Ángel; Magan, NareshZearalenone (ZEN) contamination from Fusarium graminearum colonization is particularly important in food and feed wheat, especially during post-harvest storage with legislative limits for both food and feed grain. Indicators of the relative risk from exceeding these limits would be useful. We examined the effect of different water activities (aw; 0.95–0.90) and temperature (10–25 °C) in naturally contaminated and irradiated wheat grain, both inoculated with F. graminearum and stored for 15 days on (a) respiration rate; (b) dry matter losses (DML); (c) ZEN production and (d) relationship between DML and ZEN contamination relative to the EU legislative limits. Gas Chromatography was used to measure the temporal respiration rates and the total accumulated CO2 production. There was an increase in temporal CO2 production rates in wetter and warmer conditions in all treatments, with the highest respiration in the 25 °C × 0.95 aw treatments + F. graminearum inoculation. This was reflected in the total accumulated CO2 in the treatments. The maximum DMLs were in the 0.95 aw/20–25 °C treatments and at 10 °C/0.95 aw. The DMLs were modelled to produce contour maps of the environmental conditions resulting in maximum/minimum losses. Contamination with ZEN/ZEN-related compounds were quantified. Maximum production was at 25 °C/0.95–0.93 aw and 20 °C/0.95 aw. ZEN contamination levels plotted against DMLs for all the treatments showed that at ca. <1.0% DML, there was a low risk of ZEN contamination exceeding EU legislative limits, while at >1.0% DML, the risk was high. This type of data is important in building a database for the development of a post-harvest decision support system for relative risks of different mycotoxins.Item Open Access Growth kinetic parameters and prediction of growth and zearalenone and deoxynivalenol production boundaries by three Fusarium asiaticum strains isolated from wheat(MDPI, 2022-10-25) Garcia-Cela, Esther; Verheecke-Vaessen, Carol; Ósk-Jónsdóttir, Inga; Lawson, Rita; Magan, NareshFusarium species can cause head blight of cereals worldwide. This is accompanied by impacts on yield and contamination of grains with mycotoxins. Regulations, with maximum limits, exist for the relevant Fusarium mycotoxins (e.g., type A and B trichothecenes, zearalenone and fumonisins). There is interest in a better understanding of the effect of key interacting abiotic factors which determine colonization and mycotoxin production in small grain cereals. Thus, this study examined the ecophysiological relationship between temperature and water availability (10–35 °C; water activity, aw, 0.87–0.98) on growth and production of Fusarium mycotoxins (zearelenone, ZEA; deoxynivalenol, DON; 3-acetyl deoxynivalenol, 3-Ac-DON and nivalenol, NIV) by three strains of F. asiaticum, a head blight pathogen isolated from China and becoming important in other global regions. These were carried out on simulated wheat-based matrices that identified the optimum (25 °C/0.98 aw) and marginal boundary conditions for growth (35 °C/0.90 aw) for all three strains. Contrarily, different mycotoxigenic profiles were observed between strains (p < 0.05). Four mycotoxins assessed were produced at 30 °C while cold temperature inhibited the production of NIV and ZEA, which were never detected at <20 and <15 °C, respectively. Optimal mycotoxin production conditions varied for each toxin with ZEA production which was best at 30 °C/0.93–0.95 aw, DON, 3-Ac-DON and NIV which was 0.98 aw/20–30 °C. Probabilistic models were used to predict growth and regulated mycotoxin production by the strains of F. asiaticum. This study will be beneficial in the development mitigation strategies for control of pre- and post-harvest colonization of cereals and mycotoxin contamination by this Fusarium species in cereals.Item Open Access Interacting abiotic factors affect growth and aflatoxin B1 production profiles of Aspergillus flavus strains on pistachio-based matrices and pistachio nuts(Frontiers Media, 2021-01-20) Baazeem, Alaa; Garcia-Cela, Esther; Medina, Angel; Magan, NareshPistachio nuts are an economically important commodity produced by many countries. They can be colonized by mycotoxigenic fungi, especially Aspergillus flavus, resulting in contamination with aflatoxins (AFs), especially aflatoxin B1 (AFB1), a Class 1a carcinogen. The objectives were to examine the effect of interactions between the two key abiotic factors, temperature and water activity (aw) on (a) in vitro growth and AFB1 production by four strains of A. flavus isolated from pistachio nuts, on a milled pistachio nut medium modified ionically (NaCl) and non-ionically (glycerol) in the range 20–35°C and 0.995–0.85 aw, (b) colonization of layers of raw pistachio nuts stored at different interacting temperature x aw conditions and on relative AFB1 production and (c) develop models to produce contour maps of the optimal and marginal boundary conditions for growth and AFB1 production by up to 4 strains of this species. On pistachio nut-based media, optimum growth of four strains of A. flavus was at 0.98–0.95 aw and 30–35°C. Optimum AFB1 production was at 30–35°C and 0.98 aw. No significant differences in growth was found on ionic and non-ionically modified media. Colonization of layers of raw pistachio nuts was slower and contamination with AFB1 significantly less than in in vitro studies. Contour maps based on the pooled data for up to four strains (in vitro, in situ) showed the optimum and marginal conditions for growth and AFB1 production. These data can be used to identify those conditions which represent a high, intermediate or low risk of colonization and AFB1 contamination in the pistachio nut processing chain. These results are discussed in the context of the development of appropriate intervention strategies to minimize AFB1 contamination of this economically important commodity.Item Open Access Investigation of the potential to reduce waste through sampling and spatial analysis of grain bulks(Elsevier, 2021-05-25) Kerry, Ruth; Ingram, Benjamin R.; Garcia-Cela, Esther; Magan, NareshBatches of grain are accepted or rejected based on average mycotoxin concentrations in a composite grain sample. Spatial analysis of mycotoxins in two grain bulks was performed to determine the spatial distribution of toxins, whether they were co-located and the proportions of grain over legislative limits. The 2D distribution of deoxynivalenol (DON) and ochratoxin A (OTA) in a truck load of wheat grain was analysed, as was the distribution of fumonisins (FB1 and FB2) in a 3D maize grain pile. The data had been previously analysed, but results here show that highly skewed data would need to be transformed to investigate spatial autocorrelation properly. In the truck of wheat grain, DON and OTA showed co-variation and, in contrast to previous studies, OTA showed spatial structure when converted to normal scores. Spatial analysis of the maize pile showed that FB1 and FB2 contamination levels were each highest near the outer face and base of the grain pile. Simulations for both grain bulks showed that, for average toxin concentrations close to legislative limits, the proportion of grain over the legislative limits can vary greatly and could be very small when toxin contamination is highly positively skewed. The implications of the results for management were considered. Post-harvest, strategically placed sensors could be used to monitor environmental conditions within the stored grain in real time and detect the first signs of spoilage allowing swift remediative action so less grain is wasted. Pre-harvest approaches for mycotoxin management are suggested as additional food waste reduction strategies.Item Open Access The "-omics" contributions to the understanding of mycotoxin production under diverse environmental conditions(Elsevier, 2018-08-24) Garcia-Cela, Esther; Verheecke-Vaessen, Carol; Magan, Naresh; Medina-Vayá, ÁngelExtreme environmental changes and fluctuations mainly driven by climate change will have a profound effect on natural food contaminants. Among these contaminants mycotoxins will be very important due the high adaptability of the producing fungal genera to the forecasted conditions. The availability of modern, high through-put –omic techniques, including genomics, transcriptomics, metagenomics, proteomics and metabolomics has facilitated a rapid expansion of data on the biology of mycotoxigenic fungi. This has facilitated a significant increase in our knowledge of the biological, biochemical and biophysical molecular processes regulating the production of mycotoxins, and the adaptation of these fungi to environmental stresses. In this paper we highlight recent advances where -omics approaches have been used and where they have contributed to the knowledge on how mycotoxigenic fungi adapt to diverse interacting environmental conditions and their relationship with phenotypic toxin production. We also highlight potential future directions where these approaches can be effectively utilised for the development of minimisation strategies in the context of expected climate change scenarios and the food security agenda.Item Open Access Resilience of biocontrol for aflatoxin minimisation strategies: climate change abiotic factors may affect control in non-GM and GM-maize cultivars(Frontiers Media, 2019-11-08) Marcon Gasperini, Alessandra; Rodriguez-Sixtos, Alicia; Verheecke-Vaessen, Carol; Garcia-Cela, Esther; Medina, Angel; Magan, Nareshhere has been significant interest in the development of formulations of non-toxigenic strains of Aspergillus flavus for control of toxigenic strains to reduce the aflatoxin B1 (AFB1) contamination of maize. In the future, climate change (CC) abiotic conditions of temperature (+2–4°C), CO2 (existing levels of 400 vs. 800–1,200 ppb), and drought stress will impact on the agronomy and control of pests and diseases. This study has examined (1) the effect of two-way interacting factors of water activity × temperature on colonization and AFB1 contamination of maize cobs of different ripening ages; (2) the effect of non-toxigenic strains of A. flavus (50:50 inoculum ratio) on relative control of toxigenic A. flavus and AFB1 contamination of ripening cobs; (3) post-harvest control of AFB1 by non-toxigenic strains of A. flavus in non-GM and isogenic GM maize cultivars using the same inoculum ratio; and (4) the impact of three-way interacting CC factors on relative control of AFB1 in maize cobs pre-harvest and in stored non-GM/GM cultivars. Pre-harvest colonization and AFB1 production by a toxigenic A. flavus strain was conserved at 37°C when compared with 30°C, at the three ripening stages of cob development examined:milk ripe (R3), dough (R4), and dent (R5). However, pre-harvest biocontrol with a non-toxigenic strain was only effective at the R3 and R4 stages and not at the R5 stage. This was supported by relative expression of the aflR regulatory biosynthetic gene in the different treatments. When exposed to three-way interacting CC factors for control of AFB1 pre-harvest, the non-toxigenic A. flavus strain was effective at R3 and £4 stages but not at the R5 stage. Post-harvest storage of non-GM and GM cultivars showed that control was achievable at 30°C, with slightly better control in GM-cultivars in terms of the overall inhibition of AFB1 production. However, in stored maize, the non-toxigenic strains of A. flavus had conserved biocontrol of AFB1 contamination, especially in the GM-maize cultivars under three-way interacting CC conditions (37°C × 1,000 ppm CO2 and drought stress). This was supported by the relative expression of the aflR gene in these treatments. This study suggests that the choice of the biocontrol strains, for pre- or post-harvest control, needs to take into account their resilience in CC-related abiotic conditions to ensure that control of AFB1 contamination can be conserved.Item Open Access Unveiling the effect of interacting forecasted abiotic factors on growth and Aflatoxin B1 production kinetics by Aspergillus flavus(Elsevier, 2020-05-30) Garcia-Cela, Esther; Verheecke-Vaessen, Carol; Gutierrez-Pozo, Maria; Kiaitsi, Elisavet; Gasperini, Alessandra M.; Magan, Naresh; Medina, AngelThe aim was to decipher the temporal impact of key interacting climate change (CC) abiotic factors of temperature (30 vs 37 °C), water activity (aw; 0.985 vs 0.930) and CO2 exposure (400 vs 1000 ppm) on (a) growth of Aspergillus flavus and effects on (b) gene expression of a structural (aflD) and key regulatory gene (aflR) involved in aflatoxin B1 (AFB1) biosynthesis and (c) AFB1 production on a yeast extract sucrose medium over a period of 10 days. A. flavus grew and produced AFB1 very early with toxin detected after only 48 h. Both growth and toxin production were significantly impacted by the interacting abiotic factors. The relative expression of the aflD gene was significantly influenced by temperature; aflR gene expression was mainly modulated by time. However, no clear relationship was observed for both genes with AFB1 production over the experimental time frame. The optimum temperature for AFB1 production was 30 °C. Maximum AFB1 production occurred between days 4–8. Exposure to higher CO2 conditions simulating forecasted CC conditions resulted in the amount of AFB1 produced in elevated temperature (37 °C) being higher than with the optimum temperature (30 °C) showing a potential for increased risk for human/animal health due to higher accumulation of this toxin.