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Dr. Angel Medina
Cranfield University

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Microbiology
Published: 08 June 2021 in Frontiers in Microbiology
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Bread and intermediate moisture bakery products are mainly spoiled by yeasts and filamentous fungi. The inoculum load and preservation system used determines their shelf life. To extend the shelf life of such commodities, the use of chemical preservatives is the most common way to try and control the initiation of mold spoilage of bread. This study has utilized a rapid turbidimetric assay system (Bioscreen C) to examine the temporal efficacy of calcium propionate (CP) and potassium sorbate (PS) for controlling the growth of important bread spoilage fungi. The objectives were to compare the temporal growth of strains of three important spoilage fungi Hyphopichia burtonii (HB17), Paecilomyces variotii (PV11), and Penicillium roqueforti (PR06) isolated from visibly molded bread to (a) different concentrations of CP and PS (0–128 mM), (b) temperatures (25°C, 30°C), (c) water activity (aw; 0.95, 0.97), and (d) pH (5.0, 5.5). All three abiotic factors, pH, aw, and temperature, and preservative concentrations influenced the relative growth of the species examined. In general, PS was more effective than CP in inhibiting the growth of the strains of these three species. In addition, the Time to Detection (TTD) for the efficacy of the preservatives under the interacting abiotic factors was compared. The strain of Paecilomyces variotii (PV10) was the most tolerant to the preservatives, with the shortest TTD values for both preservatives. P. roqueforti was the most sensitive with the longest TTD values under all conditions examined. These results are discussed in the context of the evolution of resistance to food-grade preservatives by such spoilage fungi in bakery products.

ACS Style

Marcelo Valle Garcia; Esther Garcia-Cela; Naresh Magan; Marina Venturini Copetti; Angel Medina. Comparative Growth Inhibition of Bread Spoilage Fungi by Different Preservative Concentrations Using a Rapid Turbidimetric Assay System. Frontiers in Microbiology 2021, 12, 1 .

AMA Style

Marcelo Valle Garcia, Esther Garcia-Cela, Naresh Magan, Marina Venturini Copetti, Angel Medina. Comparative Growth Inhibition of Bread Spoilage Fungi by Different Preservative Concentrations Using a Rapid Turbidimetric Assay System. Frontiers in Microbiology. 2021; 12 ():1.

Chicago/Turabian Style

Marcelo Valle Garcia; Esther Garcia-Cela; Naresh Magan; Marina Venturini Copetti; Angel Medina. 2021. "Comparative Growth Inhibition of Bread Spoilage Fungi by Different Preservative Concentrations Using a Rapid Turbidimetric Assay System." Frontiers in Microbiology 12, no. : 1.

Journal article
Published: 28 May 2021 in Toxins
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Pistachio nuts are an important economic tree nut crop which is used directly or processed for many food-related activities. They can become colonized by mycotoxigenic spoilage fungi, especially Aspergillus flavus, mainly resulting in contamination with aflatoxins (AFs), especially aflatoxin B1 (AFB1). The prevailing climate in which these crops are grown changes as temperature and atmospheric CO2 levels increase, and episodes of extreme wet/dry cycles occur due to human industrial activity. The objectives of this study were to evaluate the effect of interacting Climate Change (CC)-related abiotic factors of temperature (35 vs. 37 °C), CO2 (400 vs. 1000 ppm), and water stress (0.98–0.93 water activity, aw) on (a) growth (b) aflD and aflR biosynthetic gene expression and (c) AFB1 production by two strains A. flavus (AB3, AB10) in vitro on milled pistachio-based media and when colonizing layers of shelled raw pistachio nuts. The A. flavus strains were resilient in terms of growth on pistachio-based media and the colonisation of pistachio nuts with no significant difference when exposed to the interacting three-way climate-related abiotic factors. However, in vitro studies showed that AFB1 production was significantly stimulated (p< 0.05), especially when exposed to 1000 ppm CO2 at 0.98–0.95 aw and 35 °C, and sometimes in the 37 °C treatment group at 0.98 aw. The relative expression of the structural aflD gene involved in AFB1 biosynthesis was decreased or only slightly increased, relative to the control conditions at elevated CO, regardless of the aw level examined. For the regulatory aflR gene expression, there was a significant (p< 0.05) increase in 1000 ppm CO2 and 37 °C for both strains, especially at 0.95 aw. The in situ colonization of pistachio nuts resulted in a significant (p< 0.05) stimulation of AFB1 production at 35 °C and 1000 ppm CO2 for both strains, especially at 0.98 aw. At 37 °C, AFB1 production was either decreased, in strain AB3, or remained similar, as in strain AB10, when exposed to 1000 ppm CO2. This suggests that CC factors may have a differential effect, depending on the interacting conditions of temperature, exposure to CO2 and the level of water stress on AFB1 production.

ACS Style

Alaa Baazeem; Alicia Rodriguez; Angel Medina; Naresh Magan. Impacts of Climate Change Interacting Abiotic Factors on Growth, aflD and aflR Gene Expression and Aflatoxin B1 Production by Aspergillus flavus Strains In Vitro and on Pistachio Nuts. Toxins 2021, 13, 385 .

AMA Style

Alaa Baazeem, Alicia Rodriguez, Angel Medina, Naresh Magan. Impacts of Climate Change Interacting Abiotic Factors on Growth, aflD and aflR Gene Expression and Aflatoxin B1 Production by Aspergillus flavus Strains In Vitro and on Pistachio Nuts. Toxins. 2021; 13 (6):385.

Chicago/Turabian Style

Alaa Baazeem; Alicia Rodriguez; Angel Medina; Naresh Magan. 2021. "Impacts of Climate Change Interacting Abiotic Factors on Growth, aflD and aflR Gene Expression and Aflatoxin B1 Production by Aspergillus flavus Strains In Vitro and on Pistachio Nuts." Toxins 13, no. 6: 385.

Journal article
Published: 21 April 2021 in International Journal of Food Microbiology
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In the UK and Northern Europe, ripening oats can become contaminated with T-2 and HT-2 mycotoxins, produced mainly by Fusarium langsethiae. There are indicative levels related to the maximum limits for oat grain for these toxins. The objectives of this study were to examine the effect of interacting conditions of temperature (10–30 °C) and water activity (aw, 0.995–0.90) on (a) lag times prior to growth, (b) growth and (c) T-2 and HT-2 toxins by two strains of F. langsethiae isolated from oats in the UK and compare this with the type strain (Fl201059) which has been genomically sequenced, and (d) develop (and validated with published data) a probabilistic models for impacts of temperature × aw on growth and toxin production. All three strains had an optimum aw range and temperature of 0.995–0.98 and 25 °C for growth. For T-2 + HT-2 production these were 0.995 aw and 20 °C. Overall, the type strain produced higher amounts of T-2 + HT-2 with a HT-2/T-2 ratio of up to 76. Using this study data sets and those from the literature, probabilistic models were developed and validated for growth and T-2 + HT-2 toxin production in relation to temperature × aw conditions. These models, when applied in stored oats, will be beneficial in determining the conditions on the relative level of risk of contamination with these two toxins in the context of the EU indicative maximum levels.

ACS Style

Carol Verheecke-Vaessen; Esther Garcia-Cela; Alejandro Lopez-Prieto; Inga Osk Jonsdottir; Angel Medina; Naresh Magan. Water and temperature relations of Fusarium langsethiae strains and modelling of growth and T-2 and HT-2 mycotoxin production on oat-based matrices. International Journal of Food Microbiology 2021, 348, 109203 .

AMA Style

Carol Verheecke-Vaessen, Esther Garcia-Cela, Alejandro Lopez-Prieto, Inga Osk Jonsdottir, Angel Medina, Naresh Magan. Water and temperature relations of Fusarium langsethiae strains and modelling of growth and T-2 and HT-2 mycotoxin production on oat-based matrices. International Journal of Food Microbiology. 2021; 348 ():109203.

Chicago/Turabian Style

Carol Verheecke-Vaessen; Esther Garcia-Cela; Alejandro Lopez-Prieto; Inga Osk Jonsdottir; Angel Medina; Naresh Magan. 2021. "Water and temperature relations of Fusarium langsethiae strains and modelling of growth and T-2 and HT-2 mycotoxin production on oat-based matrices." International Journal of Food Microbiology 348, no. : 109203.

Preprint content
Published: 14 April 2021
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Motivation Fusarium langsethiaeis a T-2 and HT-2 mycotoxins producingFusariumspecies firstly characterised in 2004. It is commonly isolated from oats in Northern Europe. T-2 and HT-2 mycotoxins exhibit immunological and haemotological effects in animal health mainly through inhibition of protein, RNA and DNA synthesis. The development of a high-quality and comprehensively annotated assembly for this species is therefore essential in providing the molecular understanding and the mechanism of T-2 and HT-2 biosynthesis inF. langsethiaeto help develop effective control strategies. Results TheF. langsethiaeassembly was produced using PacBio long reads, which were then assembled independently using Canu, SMARTdenovo and Flye; producing a genome assembly total length of 59Mb and N50 of 3.51Mb. A total of 19,336 coding genes were identified using RNA-Seq informedab-initiogene prediction. Finally, predicting genes were annotated using the basic local alignment search tool (BLAST) against the NCBI non-redundant (NR) genome database and protein hits were annotated using InterProScan. Genes with blast hits were functionally annotated with Gene Ontology. Contact [email protected] Data availability Raw sequence reads and assembled genome can be downloaded from: GenBank under the accession JAFFKB000000000

ACS Style

Ya Zuo; Carol Verheecke-Vaessen; Corentin Molitor; Angel Medina; Naresh Magan; Fady Mohareb. De novo genome assembly and functional annotation forFusarium langsethiae. 2021, 1 .

AMA Style

Ya Zuo, Carol Verheecke-Vaessen, Corentin Molitor, Angel Medina, Naresh Magan, Fady Mohareb. De novo genome assembly and functional annotation forFusarium langsethiae. . 2021; ():1.

Chicago/Turabian Style

Ya Zuo; Carol Verheecke-Vaessen; Corentin Molitor; Angel Medina; Naresh Magan; Fady Mohareb. 2021. "De novo genome assembly and functional annotation forFusarium langsethiae." , no. : 1.

Editorial
Published: 28 January 2021 in Fungal Biology
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ACS Style

Angel Medina; Alicia Rodriguez. Editorial: Special Issue on environmental changes and mycotoxins. Fungal Biology 2021, 125, 77 .

AMA Style

Angel Medina, Alicia Rodriguez. Editorial: Special Issue on environmental changes and mycotoxins. Fungal Biology. 2021; 125 (2):77.

Chicago/Turabian Style

Angel Medina; Alicia Rodriguez. 2021. "Editorial: Special Issue on environmental changes and mycotoxins." Fungal Biology 125, no. 2: 77.

Microbiology
Published: 20 January 2021 in Frontiers in Microbiology
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Pistachio 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.

ACS Style

Alaa Baazeem; Esther Garcia-Cela; Angel Medina; Naresh Magan. Interacting Abiotic Factors Affect Growth and Aflatoxin B1 Production Profiles of Aspergillus flavus Strains on Pistachio-Based Matrices and Pistachio Nuts. Frontiers in Microbiology 2021, 11, 1 .

AMA Style

Alaa Baazeem, Esther Garcia-Cela, Angel Medina, Naresh Magan. Interacting Abiotic Factors Affect Growth and Aflatoxin B1 Production Profiles of Aspergillus flavus Strains on Pistachio-Based Matrices and Pistachio Nuts. Frontiers in Microbiology. 2021; 11 ():1.

Chicago/Turabian Style

Alaa Baazeem; Esther Garcia-Cela; Angel Medina; Naresh Magan. 2021. "Interacting Abiotic Factors Affect Growth and Aflatoxin B1 Production Profiles of Aspergillus flavus Strains on Pistachio-Based Matrices and Pistachio Nuts." Frontiers in Microbiology 11, no. : 1.

Journal article
Published: 16 October 2020 in Fungal Biology
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Penicillium verrucosum contaminates temperate cereals with ochratoxin A (OTA) during harvesting and storage. We examined the effect of temperature (25 vs 30 oC), CO2 (400 vs 1000 ppm) and matric/solute stress (-2.8 vs -7.0 MPa) on (i) growth, (ii) key OTA biosynthetic genes and (iii) OTA production on a milled wheat substrate. Growth was generally faster under matric than solute stress at 25 oC, regardless of CO2 concentrations. At 30 oC, growth of P. verrucosum was significantly reduced under solute stress in both CO2 treatments, with no growth observed at -2.8 MPa (=0.98 water activity, aw) and 1000 ppm CO2. Overall, growth patterns under solute stress was slower in elevated CO2 than under matric stress when compared with existing conditions. The otapksPV gene expression was increased under elevated CO2 levels in matric stress treatments. There was fewer effects on the otanrpsPV biosynthetic gene. This pattern was paralleled with the production of OTA under these conditions. This suggest that P. verrucosum is able to actively grow and survive in both soil and on crop debris under three way interacting climate-related abiotic factors. This resilience suggests that they would still be able to pose an OTA contamination risk in temperate cereals post-harvest.

ACS Style

Shaimaa Abdelmohsen; Carol Verheecke-Vaessen; Esther Garcia-Cela; Angel Medinaq; Naresh Magan. Dynamics of solute/matric stress interactions with climate change abiotic factors on growth, gene expression and ochratoxin A production by Penicillium verrucosum on a wheat-based matrix. Fungal Biology 2020, 125, 62 -68.

AMA Style

Shaimaa Abdelmohsen, Carol Verheecke-Vaessen, Esther Garcia-Cela, Angel Medinaq, Naresh Magan. Dynamics of solute/matric stress interactions with climate change abiotic factors on growth, gene expression and ochratoxin A production by Penicillium verrucosum on a wheat-based matrix. Fungal Biology. 2020; 125 (1):62-68.

Chicago/Turabian Style

Shaimaa Abdelmohsen; Carol Verheecke-Vaessen; Esther Garcia-Cela; Angel Medinaq; Naresh Magan. 2020. "Dynamics of solute/matric stress interactions with climate change abiotic factors on growth, gene expression and ochratoxin A production by Penicillium verrucosum on a wheat-based matrix." Fungal Biology 125, no. 1: 62-68.

Review
Published: 29 September 2020 in Microorganisms
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Toxigenic fungi and mycotoxins are very common in food crops, with noticeable differences in their host specificity in terms of pathogenicity and toxin contamination. In addition, such crops may be infected with mixtures of mycotoxigenic fungi, resulting in multi-mycotoxin contamination. Climate represents the key factor in driving the fungal community structure and mycotoxin contamination levels pre- and post-harvest. Thus, there is significant interest in understanding the impact of interacting climate change-related abiotic factors (especially increased temperature, elevated CO2 and extremes in water availability) on the relative risks of mycotoxin contamination and impacts on food safety and security. We have thus examined the available information from the last decade on relative risks of mycotoxin contamination under future climate change scenarios and identified the gaps in knowledge. This has included the available scientific information on the ecology, genomics, distribution of toxigenic fungi and intervention strategies for mycotoxin control worldwide. In addition, some suggestions for prediction and prevention of mycotoxin risks are summarized together with future perspectives and research needs for a better understanding of the impacts of climate change scenarios.

ACS Style

Giancarlo Perrone; Massimo Ferrara; Angel Medina; Michelangelo Pascale; Naresh Magan. Toxigenic Fungi and Mycotoxins in a Climate Change Scenario: Ecology, Genomics, Distribution, Prediction and Prevention of the Risk. Microorganisms 2020, 8, 1496 .

AMA Style

Giancarlo Perrone, Massimo Ferrara, Angel Medina, Michelangelo Pascale, Naresh Magan. Toxigenic Fungi and Mycotoxins in a Climate Change Scenario: Ecology, Genomics, Distribution, Prediction and Prevention of the Risk. Microorganisms. 2020; 8 (10):1496.

Chicago/Turabian Style

Giancarlo Perrone; Massimo Ferrara; Angel Medina; Michelangelo Pascale; Naresh Magan. 2020. "Toxigenic Fungi and Mycotoxins in a Climate Change Scenario: Ecology, Genomics, Distribution, Prediction and Prevention of the Risk." Microorganisms 8, no. 10: 1496.

Journal article
Published: 23 September 2020 in Microorganisms
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The objective of this study was to examine the effect of treatment of Arabica green coffee beans with gaseous ozone (O3) for the control of ochratoxigenic fungi and ochratoxin A (OTA) contamination by Aspergillus westerdijkiae, A. ochraceus, and A. carbonarius during storage. Studies included (i) relative control of the populations of each of these three species when inoculated on irradiated green coffee beans of different initial water availabilities using 400 and 600 ppm gaseous O3 treatment for 60 min at a flow rate of 6 L−1 and on OTA contamination after 12 days storage at 30 °C and (ii) effect of 600 ppm O3 treatment on natural populations of green stored coffee beans at 0.75, 0.90, and 0.95 water activity (aw) or with additional inoculum of a mixture of these three ochratoxigenic fungi after treatment and storage for 12 days at 30 °C on fungal populations and OTA contamination. Exposure to 400 and 600 ppm O3 of coffee beans inoculated with the toxigenic species showed that there was less effect on fungal populations at the lowered aw (0.75). However, toxigenic fungal populations significantly increased 48 h after exposure and when stored at 0.90 and 0.95 aw for 12 days. All three species produced high amounts of OTA in both O3 treatments of the wetter coffee beans at 0.90 and 0.95 aw. Gaseous O3 (600 ppm) treatment of naturally contaminated green coffee beans had little effect on fungal populations after treatment, regardless of the initial aw level. However, after storage, there was some reduction (26%) observed in coffee at 0.95 aw. In addition, no fungal populations or OTA contamination occurred in the 0.75 and 0.90 aw treatments after exposure to 600 ppm gaseous O3 and storage for 12 days. It appears that under wetter conditions (≥0.90–95 aw) it is unlikely that fungal populations and OTA contamination of stored coffee beans, even with such high O3 concentrations would be controlled. The results are discussed in the context of potential application of O3 as an intervention system for stored coffee post-fermentation and during medium term storage and transport.

ACS Style

Asya Akbar; Angel Medina; Naresh Magan. Potential Control of Mycotoxigenic Fungi and Ochratoxin A in Stored Coffee Using Gaseous Ozone Treatment. Microorganisms 2020, 8, 1462 .

AMA Style

Asya Akbar, Angel Medina, Naresh Magan. Potential Control of Mycotoxigenic Fungi and Ochratoxin A in Stored Coffee Using Gaseous Ozone Treatment. Microorganisms. 2020; 8 (10):1462.

Chicago/Turabian Style

Asya Akbar; Angel Medina; Naresh Magan. 2020. "Potential Control of Mycotoxigenic Fungi and Ochratoxin A in Stored Coffee Using Gaseous Ozone Treatment." Microorganisms 8, no. 10: 1462.

Journal article
Published: 20 August 2020 in Microorganisms
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We examined the resilience of strains of Aspergillus westerdijkiae in terms of growth and ochratoxin A (OTA) production in relation to: (a) two-way interacting climate-related abiotic factors of water activity (aw, 0.99–0.90) × temperature (25–37 °C) on green coffee and roasted coffee-based media; (b) three-way climate-related abiotic factors (temperature, 30 vs. 35 °C; water stress, 0.98–0.90 aw; CO2, 400 vs. 1000 ppm) on growth and OTA production on a 6% green coffee extract-based matrix; and (c) the effect of three-way climate-related abiotic factors on OTA production in stored green coffee beans. Four strains of A. westerdijkiae grew equally well on green or roasted coffee-based media with optimum 0.98 aw and 25–30 °C. Growth was significantly slower on roasted than green coffee-based media at 35 °C, regardless of aw level. Interestingly, on green coffee-based media OTA production was optimum at 0.98–0.95 aw and 30 °C. However, on roasted coffee-based media very little OTA was produced. Three-way climate-related abiotic factors were examined on two of these strains. These interacting factors significantly reduced growth of the A. westerdijkiae strains, especially at 35 °C × 1000 ppm CO2 and all aw levels when compared to 30 °C. At 35 °C × 1000 ppm CO2 there was some stimulation of OTA production by the two A. westerdijkiae strains, especially under water stress. In stored green coffee beans optimum OTA was produced at 0.95–0.97 aw/30 °C. In elevated CO2 and 35 °C, OTA production was stimulated at 0.95–0.90 aw.

ACS Style

Asya Akbar; Angel Medina; Naresh Magan. Resilience of Aspergillus westerdijkiae Strains to Interacting Climate-Related Abiotic Factors: Effects on Growth and Ochratoxin A Production on Coffee-Based Medium and in Stored Coffee. Microorganisms 2020, 8, 1268 .

AMA Style

Asya Akbar, Angel Medina, Naresh Magan. Resilience of Aspergillus westerdijkiae Strains to Interacting Climate-Related Abiotic Factors: Effects on Growth and Ochratoxin A Production on Coffee-Based Medium and in Stored Coffee. Microorganisms. 2020; 8 (9):1268.

Chicago/Turabian Style

Asya Akbar; Angel Medina; Naresh Magan. 2020. "Resilience of Aspergillus westerdijkiae Strains to Interacting Climate-Related Abiotic Factors: Effects on Growth and Ochratoxin A Production on Coffee-Based Medium and in Stored Coffee." Microorganisms 8, no. 9: 1268.

Journal article
Published: 01 August 2020 in Microorganisms
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Fusarium causes significant post-harvest quality losses and mycotoxin contamination in stored wheat but the colonisation dynamics of the grain and how this may be affected by the initial inoculum position in the grain mass is poorly understood. This study examined the 3D growth kinetics and mycotoxin production (deoxynivalenol and zearalenone) by F. graminearum during hyphal colonisation from different initial inoculum positions in wheat microcosms (top-centre, bottom-centre, and bottom-side) maintained at two water activities (aw; 0.95 and 0.97). Clear jars were used to visually follow the colonisation dynamics. Fungal respiration and associated dry matter loss (DML) and ergosterol were also quantified. Colonisation dynamics was shown to be affected by the inoculation position. At the end of the colonisation process, fungal respiration and DML were driven by the inoculation position, and the latter also by the prevailing aw. Fungal biomass (ergosterol) was mainly affected by the aw. The initial inoculum position did not affect the relative mycotoxin production. There was a positive correlation between respiration and ergosterol, and between mycotoxin production and colonisation indicators. We suggest that spatially explicit predictive models can be used to better understand the colonisation patterns and mycotoxin contamination of stored cereal commodities and to aid more effective post-harvest management.

ACS Style

Xavier Portell; Carol Verheecke-Vaessen; Rosa Torrelles-Ràfales; Angel Medina; Wilfred Otten; Naresh Magan; Esther García-Cela. Three-Dimensional Study of F. graminearum Colonisation of Stored Wheat: Post-Harvest Growth Patterns, Dry Matter Losses and Mycotoxin Contamination. Microorganisms 2020, 8, 1170 .

AMA Style

Xavier Portell, Carol Verheecke-Vaessen, Rosa Torrelles-Ràfales, Angel Medina, Wilfred Otten, Naresh Magan, Esther García-Cela. Three-Dimensional Study of F. graminearum Colonisation of Stored Wheat: Post-Harvest Growth Patterns, Dry Matter Losses and Mycotoxin Contamination. Microorganisms. 2020; 8 (8):1170.

Chicago/Turabian Style

Xavier Portell; Carol Verheecke-Vaessen; Rosa Torrelles-Ràfales; Angel Medina; Wilfred Otten; Naresh Magan; Esther García-Cela. 2020. "Three-Dimensional Study of F. graminearum Colonisation of Stored Wheat: Post-Harvest Growth Patterns, Dry Matter Losses and Mycotoxin Contamination." Microorganisms 8, no. 8: 1170.

Journal article
Published: 01 July 2020 in World Mycotoxin Journal
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Penicillium verrucosum survives in soil and on cereal debris. It colonises grain during harvesting, drying and storage. There is no information on the relative tolerance of P. verrucosum to solute and matric stress in terms of colonisation, or on the biosynthetic toxin gene clusters or ochratoxin A (OTA) production. The objectives were to examine the effect of ionic and non-ionic solute and matric potential stress on (a) growth, (b) expression of two toxin biosynthetic genes otapksPV and otanrpsPV, and (c) OTA production by a strain of P. verrucosum. Optimum growth and OTA production were at -7.0 MPa (= 0.95 water activity, aw) and -1.4 MPa (= 0.99 aw), respectively, regardless of whether solute (Ψs) or matric (Ψm) stress was imposed. P. verrucosum was more sensitive to ionic solute stress (NaCl) with no growth at -19.6 MPa (=0.86 aw) while growth still occurred in the non-ionic solute (glycerol) and matric stress treatments. Relative gene expression of the biosynthetic genes using PCR (RT-qPCR) showed that the otapksPV gene was expressed over a wide range of ionic/non-ionic solute stress conditions (-1.4 to -14.0 MPa; = 0.99-0.90 aw). The highest expression was in the non-ionic Ψs stress treatments at -7.0 MPa (= 0.95 aw). However, the otanrpsPV gene was significantly up regulated under Ψm stress, especially with freely available water (-1.4 MPa = 0.99 aw). OTA production was significantly decreased as Ψs or Ψm stress were imposed. Limited OTA production occurred in the driest treatments under Ψs and Ψm stress respectively. The impact of these two types of stresses on the growth of P. verrucosum was quite different from that for OTA production. The results are discussed in the context of the life cycle and ecological characteristics of this species in contaminating cereals with OTA in the post-harvest phase of the cereal chain.

ACS Style

S. Abdelmohsen; Carol Verheecke; Esther García-Cela; Angel Medina-Vaya; N. Magan. Solute and matric potential stress on Penicillium verrucosum: impact on growth, gene expression and ochratoxin A production. World Mycotoxin Journal 2020, 13, 345 -353.

AMA Style

S. Abdelmohsen, Carol Verheecke, Esther García-Cela, Angel Medina-Vaya, N. Magan. Solute and matric potential stress on Penicillium verrucosum: impact on growth, gene expression and ochratoxin A production. World Mycotoxin Journal. 2020; 13 (3):345-353.

Chicago/Turabian Style

S. Abdelmohsen; Carol Verheecke; Esther García-Cela; Angel Medina-Vaya; N. Magan. 2020. "Solute and matric potential stress on Penicillium verrucosum: impact on growth, gene expression and ochratoxin A production." World Mycotoxin Journal 13, no. 3: 345-353.

Journal article
Published: 29 June 2020 in Letters in Applied Microbiology
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The objective was to screen 10 snake venoms for their efficacy to control growth and mycotoxin production by important mycotoxigenic fungi including Aspergillus flavus, A. westerdijkiae, Penicillium verrucosum, Fusarium graminearum and F. langsethiae. The Bioscreen C rapid assay system was used. The venoms from the Viperidae snake family delayed growth of some of the test fungi, especially F. graminearum and F. langsethiae and sometimes A. flavus. Some were also able to reduce mycotoxin production. The two most potent crude snake venoms (Naja nigricollis and N. siamensis; 41 and 43 fractions respectively) were further fractionated and 83/84 of these fractions were able to reduce mycotoxin production by >90% in two of the mycotoxigenic fungi examined. This study suggests that there may be significant potential for the identification of novel fungistatic/fungicidal bioactive compounds as preservatives of raw and processed food commodities post-harvest from such snake venoms.

ACS Style

C. Verheecke‐Vaessen; J. Monte; Esther García-Cela; N. Magan; A. Medina. Proof of concept: could snake venoms be a potential source of bioactive compounds for control of mould growth and mycotoxin production. Letters in Applied Microbiology 2020, 71, 459 -465.

AMA Style

C. Verheecke‐Vaessen, J. Monte, Esther García-Cela, N. Magan, A. Medina. Proof of concept: could snake venoms be a potential source of bioactive compounds for control of mould growth and mycotoxin production. Letters in Applied Microbiology. 2020; 71 (5):459-465.

Chicago/Turabian Style

C. Verheecke‐Vaessen; J. Monte; Esther García-Cela; N. Magan; A. Medina. 2020. "Proof of concept: could snake venoms be a potential source of bioactive compounds for control of mould growth and mycotoxin production." Letters in Applied Microbiology 71, no. 5: 459-465.

Original research
Published: 08 June 2020 in The Plant Genome
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Fusarium langsethiae is a symptomless pathogen of oat panicles that produces T‐2 and HT‐2 mycotoxins, two of the most potent trichothecenes produced by Fusarium fungi in cereals. In the last few years, the levels of these mycotoxin in oat grain has increased and the European commission have already recommended a maximum level for of 1000 μg kg−1 for unprocessed oat for human consumption. The optimal and most sustainable way of combating infection and mycotoxin contamination is by releasing resistant oat varieties. Here the objective was to determine if we could identify any genomic loci associated with either the accumulation of F. langsethiae DNA or mycotoxins in the grain. In each of two years, field trials were conducted wherein 190 spring oat varieties were inoculated with a mixture of three isolate of the pathogen. Mycotoxins were quantified using liquid chromatography–tandem mass spectrometry. Varieties were genotyped using 16,863 genotyping by sequencing markers. Genome‐wide association studies associated 5 SNPs in the linkage group Mr06 with T‐2 + HT‐2 mycotoxin accumulation. Markers were highly correlated, and a single QTL was identified. The marker avgbs_6K_95238.1 mapped within genes showing similarity to lipase, lipase‐like or lipase precursor mRNA sequences and zinc‐finger proteins. These regions have previously been shown to confer a significant increase in resistance to Fusarium species.

ACS Style

Julio Isidro‐Sánchez; Kane D'Arcy Cusack; Carol Verheecke; Amal Kahla; Wubishet Bekele; Fiona Doohan; Naresh Magan; Angel Medina. Genome‐wide association mapping ofFusarium langsethiaeinfection and mycotoxin accumulation in oat (Avena sativaL.). The Plant Genome 2020, 13, e20023 .

AMA Style

Julio Isidro‐Sánchez, Kane D'Arcy Cusack, Carol Verheecke, Amal Kahla, Wubishet Bekele, Fiona Doohan, Naresh Magan, Angel Medina. Genome‐wide association mapping ofFusarium langsethiaeinfection and mycotoxin accumulation in oat (Avena sativaL.). The Plant Genome. 2020; 13 (2):e20023.

Chicago/Turabian Style

Julio Isidro‐Sánchez; Kane D'Arcy Cusack; Carol Verheecke; Amal Kahla; Wubishet Bekele; Fiona Doohan; Naresh Magan; Angel Medina. 2020. "Genome‐wide association mapping ofFusarium langsethiaeinfection and mycotoxin accumulation in oat (Avena sativaL.)." The Plant Genome 13, no. 2: e20023.

Journal article
Published: 03 June 2020 in Microbial Cell Factories
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Background Xylitol is a commercially important chemical with multiple applications in the food and pharmaceutical industries. According to the US Department of Energy, xylitol is one of the top twelve platform chemicals that can be produced from biomass. The chemical method for xylitol synthesis is however, expensive and energy intensive. In contrast, the biological route using microbial cell factories offers a potential cost-effective alternative process. The bioprocess occurs under ambient conditions and makes use of biocatalysts and biomass which can be sourced from renewable carbon originating from a variety of cheap waste feedstocks. Result In this study, biotransformation of xylose to xylitol was investigated using Yarrowia lipolytica, an oleaginous yeast which was firstly grown on a glycerol/glucose for screening of co-substrate, followed by media optimisation in shake flask, scale up in bioreactor and downstream processing of xylitol. A two-step medium optimization was employed using central composite design and artificial neural network coupled with genetic algorithm. The yeast amassed a concentration of 53.2 g/L xylitol using pure glycerol (PG) and xylose with a bioconversion yield of 0.97 g/g. Similar results were obtained when PG was substituted with crude glycerol (CG) from the biodiesel industry (titer: 50.5 g/L; yield: 0.92 g/g). Even when xylose from sugarcane bagasse hydrolysate was used as opposed to pure xylose, a xylitol yield of 0.54 g/g was achieved. Xylitol was successfully crystallized from PG/xylose and CG/xylose fermentation broths with a recovery of 39.5 and 35.3%, respectively. Conclusion To the best of the author’s knowledge, this study demonstrates for the first time the potential of using Y. lipolytica as a microbial cell factory for xylitol synthesis from inexpensive feedstocks. The results obtained are competitive with other xylitol producing organisms.

ACS Style

Ashish Prabhu; Dominic J. Thomas; Rodrigo Ledesma-Amaro; Gary A. Leeke; Angel Medina; Carol Verheecke; Frederic Coulon; Deepti Agrawal; Vinod Kumar. Biovalorisation of crude glycerol and xylose into xylitol by oleaginous yeast Yarrowia lipolytica. Microbial Cell Factories 2020, 19, 1 -18.

AMA Style

Ashish Prabhu, Dominic J. Thomas, Rodrigo Ledesma-Amaro, Gary A. Leeke, Angel Medina, Carol Verheecke, Frederic Coulon, Deepti Agrawal, Vinod Kumar. Biovalorisation of crude glycerol and xylose into xylitol by oleaginous yeast Yarrowia lipolytica. Microbial Cell Factories. 2020; 19 (1):1-18.

Chicago/Turabian Style

Ashish Prabhu; Dominic J. Thomas; Rodrigo Ledesma-Amaro; Gary A. Leeke; Angel Medina; Carol Verheecke; Frederic Coulon; Deepti Agrawal; Vinod Kumar. 2020. "Biovalorisation of crude glycerol and xylose into xylitol by oleaginous yeast Yarrowia lipolytica." Microbial Cell Factories 19, no. 1: 1-18.

Journal article
Published: 30 May 2020 in Fungal Biology
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The 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 hours. 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, the amount of AFB1 produced in elevated temperature (37 °C) was higher than with the optimum temperature (30 °C) showing a potential for increased risk for human/animal health due to higher accumulation of AFB1.

ACS Style

Esther García-Cela; Carol Verheecke; Maria Gutierrez-Pozo; Elisavet Kiaitsi; Alessandra Marcon Gasperini; Naresh Magan; Angel Medina. Unveiling the effect of interacting forecasted abiotic factors on growth and aflatoxin B1 production kinetics by Aspergillus flavus. Fungal Biology 2020, 125, 89 -94.

AMA Style

Esther García-Cela, Carol Verheecke, Maria Gutierrez-Pozo, Elisavet Kiaitsi, Alessandra Marcon Gasperini, Naresh Magan, Angel Medina. Unveiling the effect of interacting forecasted abiotic factors on growth and aflatoxin B1 production kinetics by Aspergillus flavus. Fungal Biology. 2020; 125 (2):89-94.

Chicago/Turabian Style

Esther García-Cela; Carol Verheecke; Maria Gutierrez-Pozo; Elisavet Kiaitsi; Alessandra Marcon Gasperini; Naresh Magan; Angel Medina. 2020. "Unveiling the effect of interacting forecasted abiotic factors on growth and aflatoxin B1 production kinetics by Aspergillus flavus." Fungal Biology 125, no. 2: 89-94.

Journal article
Published: 25 February 2020 in Toxins
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Aflatoxin contamination of foodstuffs poses a serious risk to food security, and it is essential to search for new control methods to prevent these toxins entering the food chain. Several essential oils are able to reduce the growth and mycotoxin biosynthesis of toxigenic species, although their efficiency is strongly influenced by the environmental conditions. In this work, the effectiveness of Satureja montana and Origanum virens essential oils to control Aspergillus flavus growth was evaluated under three water activity levels (0.94, 0.96 and 0.98 aw) using a Bioscreen C, a rapid in vitro spectrophotometric technique. The aflatoxin concentrations at all conditions tested were determined by HPLC-FLD. Aspergillus flavus growth was delayed by both essential oil treatments. However, only S. montana essential oil was able to significantly affect aflatoxin production, although the inhibition percentages widely differed among water activities. The most significant reduction was observed at 0.96 aw, which is coincident with the conditions in which A. flavus reached the highest levels of aflatoxin production. On the contrary, the treatment with S. montana essential oil was not effective in significantly reducing aflatoxin production at 0.94 aw. Therefore, it is important to study the interaction of the new control compounds with environmental factors before their application in food matrices, and in vitro ecophysiological studies are a good option since they provide accurate and rapid results.

ACS Style

Marta García-Díaz; Jessica Gil-Serna; Belén Patiño; Esther García-Cela; Naresh Magan; Ángel Medina. Assessment of the Effect of Satureja montana and Origanum virens Essential Oils on Aspergillus flavus Growth and Aflatoxin Production at Different Water Activities. Toxins 2020, 12, 142 .

AMA Style

Marta García-Díaz, Jessica Gil-Serna, Belén Patiño, Esther García-Cela, Naresh Magan, Ángel Medina. Assessment of the Effect of Satureja montana and Origanum virens Essential Oils on Aspergillus flavus Growth and Aflatoxin Production at Different Water Activities. Toxins. 2020; 12 (3):142.

Chicago/Turabian Style

Marta García-Díaz; Jessica Gil-Serna; Belén Patiño; Esther García-Cela; Naresh Magan; Ángel Medina. 2020. "Assessment of the Effect of Satureja montana and Origanum virens Essential Oils on Aspergillus flavus Growth and Aflatoxin Production at Different Water Activities." Toxins 12, no. 3: 142.

Original article
Published: 20 January 2020 in Mycotoxin Research
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The objectives of this study were to determine the efficacy of metabolites of a Streptomyces strain AS1 on (a) spore germination, (b) mycelial growth, (c) control of mycotoxins produced by Penicillium verrucosum (ochratoxin A, OTA), Fusarium verticillioides (fumonisins, FUMs) and Aspergillus fumigatus (gliotoxin) and (d) identify the predominant metabolites involved in control. Initial screening showed that the Streptomyces AS1 strain was able to inhibit the mycelial growth of the three species at a distance, due to the release of secondary metabolites. A macroscopic screening system showed that the overall Index of Dominance against all three toxigenic fungi was inhibition at a distance. Subsequent studies showed that the metabolite mixture from the Streptomyces AS1 strain was very effective at inhibiting conidial germination of P. verrucosum, but less so against conidia of A. fumigatus and F. verticillioides. The efficacy was confirmed in studies on a conducive semi-solid YES medium in BioScreen C assays. Using the BioScreen C and the criteria of Time to Detection (TTD) at an OD = 0.1 showed good efficacy against P. verrucosum when treated with the Streptomyces AS1 extract at 0.95 and 0.99 water activity (aw) when compared to the other two species tested, indicating good efficacy. The effective dose for 50% control of growth (ED50) at 0.95 and 0.99 aw were approx. 0.005 ng/ml and 0.15 μg/ml, respectively, with the minimum inhibitory concentration (MIC) at both aw levels requiring > 40 μg/ml. In addition, OTA production was completely inhibited by 2.5 μg/ml AS1 extract at both aw levels in the in vitro assays. Ten metabolites were identified with four of these being predominant in concentrations > 2 μg/g dry weight biomass. These were identified as valinomycin, cyclo(L-Pro-L-Tyr), cyclo(L-Pro-L-Val) and brevianamide F.

ACS Style

A. Mohd Danial; Angel Medina-Vaya; Michael Sulyok; N. Magan. Efficacy of metabolites of a Streptomyces strain (AS1) to control growth and mycotoxin production by Penicillium verrucosum, Fusarium verticillioides and Aspergillus fumigatus in culture. Mycotoxin Research 2020, 36, 225 -234.

AMA Style

A. Mohd Danial, Angel Medina-Vaya, Michael Sulyok, N. Magan. Efficacy of metabolites of a Streptomyces strain (AS1) to control growth and mycotoxin production by Penicillium verrucosum, Fusarium verticillioides and Aspergillus fumigatus in culture. Mycotoxin Research. 2020; 36 (2):225-234.

Chicago/Turabian Style

A. Mohd Danial; Angel Medina-Vaya; Michael Sulyok; N. Magan. 2020. "Efficacy of metabolites of a Streptomyces strain (AS1) to control growth and mycotoxin production by Penicillium verrucosum, Fusarium verticillioides and Aspergillus fumigatus in culture." Mycotoxin Research 36, no. 2: 225-234.

Journal article
Published: 12 November 2019 in Fungal Biology
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Little is known on the impact that climate change (CC) may have on Aspergillus carbonarius and Ochratoxin A (OTA) contamination of grapes, especially in the Mediterranean region - a hot spot for the impact of CC scenarios with temperature expected to increase by +2-5°C and CO2 to double or triple (400 vs 800/1200 ppm). This study examined the effect of (i) current and increased temperature in the alternating 11.5h dark/12.5h light cycle (15-28°C vs 18-34°C), representative of the North Apulia area, South Italy and (ii) existing and predicted CO2 concentrations (400 vs 1000 ppm), on growth, expression of biosynthetic genes (AcOTApks, AcOTAnrps, AcOTAhal, AcOTAp450, AcOTAbZIP) and regulatory genes of Velvet complex (laeA/veA/velB, “velvet complex”) involved in OTA biosynthesis and OTA phenotypic production by three strains of A. carbonarius. The experiments made on a grape-based matrix showed that elevated CO2 resulted in a general stimulation of growth and OTA production. These results were supported by the up-regulation of both structural and regulatory genes involved in the OTA biosynthesis in elevated CO2 condition. Our work has shown for the first time that elevated CO2 concentration in the Mediterranean region may result in an increased risk of OTA contamination in the wine production chain.

ACS Style

Carla Cervini; Carol Verheecke-Vaessen; Massimo Ferrara; Esther García-Cela; Donato Magistà; Angel Medina; Antonia Gallo; Naresh Magan; Giancarlo Perrone. Interacting climate change factors (CO2 and temperature cycles) effects on growth, secondary metabolite gene expression and phenotypic ochratoxin A production by Aspergillus carbonarius strains on a grape-based matrix. Fungal Biology 2019, 125, 115 -122.

AMA Style

Carla Cervini, Carol Verheecke-Vaessen, Massimo Ferrara, Esther García-Cela, Donato Magistà, Angel Medina, Antonia Gallo, Naresh Magan, Giancarlo Perrone. Interacting climate change factors (CO2 and temperature cycles) effects on growth, secondary metabolite gene expression and phenotypic ochratoxin A production by Aspergillus carbonarius strains on a grape-based matrix. Fungal Biology. 2019; 125 (2):115-122.

Chicago/Turabian Style

Carla Cervini; Carol Verheecke-Vaessen; Massimo Ferrara; Esther García-Cela; Donato Magistà; Angel Medina; Antonia Gallo; Naresh Magan; Giancarlo Perrone. 2019. "Interacting climate change factors (CO2 and temperature cycles) effects on growth, secondary metabolite gene expression and phenotypic ochratoxin A production by Aspergillus carbonarius strains on a grape-based matrix." Fungal Biology 125, no. 2: 115-122.

Journal article
Published: 08 November 2019 in Frontiers in Microbiology
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There 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.

ACS Style

Alessandra Marcon Gasperini; Alicia Rodriguez-Sixtos; Carol Verheecke; Esther García-Cela; Angel Medina; Naresh Magan. Resilience of Biocontrol for Aflatoxin Minimization Strategies: Climate Change Abiotic Factors May Affect Control in Non-GM and GM-Maize Cultivars. Frontiers in Microbiology 2019, 10, 2525 .

AMA Style

Alessandra Marcon Gasperini, Alicia Rodriguez-Sixtos, Carol Verheecke, Esther García-Cela, Angel Medina, Naresh Magan. Resilience of Biocontrol for Aflatoxin Minimization Strategies: Climate Change Abiotic Factors May Affect Control in Non-GM and GM-Maize Cultivars. Frontiers in Microbiology. 2019; 10 ():2525.

Chicago/Turabian Style

Alessandra Marcon Gasperini; Alicia Rodriguez-Sixtos; Carol Verheecke; Esther García-Cela; Angel Medina; Naresh Magan. 2019. "Resilience of Biocontrol for Aflatoxin Minimization Strategies: Climate Change Abiotic Factors May Affect Control in Non-GM and GM-Maize Cultivars." Frontiers in Microbiology 10, no. : 2525.