Browsing by Author "Verheecke-Vaessen, Carol"

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    Acclimatisation of Fusarium langsethiae, F. poae and F. sporotrichioides to elevated CO2: impact on fungal growth and mycotoxin production on oat-based media
    (Elsevier, 2023-03-28) Kahla, Amal; Verheecke-Vaessen, Carol; Delpino-Deelias, Mariluz; Gutierrez-Pozo, Maria; Medina, Angel; Magan, Naresh; Doohan, Fiona
    Oats are highly susceptible to infection by Fusarium species, especially F. langsethiae, F. poae and F. sporotrichioides which contaminate the grain with mycotoxins. Climate change is expected to affect fungal colonisation and associated mycotoxin production. The objective of this study was to examine the effect of acclimatisation to elevated CO2 on the growth and mycotoxin production capacity of these fungal species. Strains of F. langsethiae (FL; seven strains), F. poae (FP; two strains) and F. sporotrichioides (FS; one strain) were acclimatised by sub-culturing for 10 generations at either 400 or 1000 ppm CO2 under diurnal temperature conditions. At each sub-culturing, the effect of acclimatisation to elevated CO2 on (a) lag phase prior to growth, (b) growth rate on oat-based media was assessed. Additionally, the production of type A trichothecenes and related toxic secondary metabolites of sub-cultures after 1, 7 and 10 generations were assessed using LC-MS/MS qTRAP. The results showed that Fusarium strains had an increased lag time and growth rate in response to the combined effect of sub-culturing and elevated CO2 levels. T-2 + HT-2 production was affected by elevated CO2 in strain FL4 (7.1-fold increase) and a decrease in strain FL1 (2.0-fold decrease) at the first sub-culturing and FS (1.3-fold decrease) after 7 sub-cultures compared to ambient conditions. The effect of sub-culturing on T-2 + HT-2 production varied depending on the fungal strain. For strain FL4, significantly less T-2 + HT-2 toxins were produced after 10 generations (4.4-fold decrease) as compared to that under elevated CO2 conditions after one sub-culture, and no change was observed under ambient conditions. The FS strain showed significant stimulation of T-2 + HT-2 toxin production after 10 sub-cultured generations (1.1-fold increase) compared to the initial sub-culture of this strain under elevated CO2 conditions. The production of other toxic secondary metabolites was generally not impacted by elevated CO2 conditions or by sub-culture for 10 generations, with the exceptions of FL1 and FP1. FL1 produced significantly more neosolaniol after 10 generations, when compared to those after 1 and 7, regardless of the CO2 conditions. For FP1, elevated CO2 significantly triggered beauvericin production after an initial sub-culture when compared to ambient conditions at the same sub-culture stage (29-fold). FP1 acclimatisation to elevated CO2 led to a decrease of beauvericin production after 10 generations when compared to 1 (6-fold). In contrast, sub-culturing for 10 generations compared to 1 under ambient CO2 conditions resulted in an increase in this toxin (12-fold).
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    Actinobacteria: an underestimated source of potential microbial biocontrol agents against fusarium-related diseases in cultivated crops
    (Springer, 2023-07-28) Djemouai, Nadjette; Meklat, Atika; Yekkour, Amine; Verheecke-Vaessen, Carol
    Crop infections with Fusarium spp. and associated mycotoxins have devastating economic implications and are a significant limitation to fifteen of the seventeen United Nations Sustainable Development Goals. Therefore, it is necessary to develop innovative strategies to reduce or eliminate diseases caused by Fusarium spp. in cultivated crops. Management of Fusarium-related diseases using beneficial microorganisms is a promising and eco-friendly solution. In this context, actinobacteria are considered one of the best candidates because of their multifunctional properties, which consist in the reduction of Fusarium spp. diseases and the promotion of plant growth. Actinobacteria represent a large Gram-positive bacterial phylum that is widespread in different environments, especially in soil. They are principally known for their versatile capacity to produce biologically active molecules with potential applications in different fields, including agriculture. As Fusarium species threaten diverse crops worldwide and cause global yield and quality losses that can negatively impact food security, the use of actinobacteria for plant diseases management is gaining interest as a safer and more potent alternative to ineffective synthetic-based pesticides. Thus, this work aims to review and highlight the importance of actinobacteria as microbial biocontrol agents and discuss the current research on Fusarium spp. diseases with a focus on species that threaten economically important crops, such as F. graminearum, F. oxysporum, F. solani, and F. culmorum. This review also presents actinobacteria-based products that have been patented for Fusarium disease control. We aim to provide valuable data, guidance and advancements for future research on microbial biocontrol against Fusarium-related diseases. In addition, this review emphasizes the need for further research about the impact of actinobacteria-Fusarium interactions on mycotoxin production. It also highlights the need of in-depth understanding microbial biocontrol mechanisms to ensure safe and sustainable crop production worldwide.
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    Assessment of agricultural practices by Ethiopian women farmers: existence of gender disparities in access to mycotoxins training
    (Wageningen Academic Publishers, 2023-01-01) Cervini, Carla; Abegaz, Beimnet; Mohammed, Abdi; Elias, Raisa; Medina, Angel; Gebre, Kiros; Verheecke-Vaessen, Carol
    Ethiopia is one of the countries with the lowest gender-equality performance in sub-Saharan Africa being ranked 121/134 in terms of the magnitude and scope of gender disparities by the United Nations Women’s Organisation. Within the farming communities, women represent 70% of the labour force, but they are neglected from accessing training events run by Ethiopian Universities (e.g. Haramaya University). A survey to assess the existence of gender disparities among Ethiopian women farmers with respect to agricultural labour and mycotoxins knowledge was conducted on three hundred and forty-nine women from the Oromia and Amhara regions. A higher illiteracy rate was found in women compared to men from both Oromia and Amhara regions. Women played a key role in agricultural activities while having limited access to modern technologies compared to their male counterparts. Women were mainly responsible for sorting spoiled crops. Especially in Amhara, these were intended for home consumption, representing a serious health risk for local people. Overall, women from Amhara were more aware than women from Oromia about what mycotoxins are (e.g. aflatoxins), their impact and risk of occurrence in crops. Women in Amhara were also more intended to act towards mycotoxins in the future compared to women from Oromia. Only 0.24% of women have previously attended a training on mycotoxins. The radio seemed to be the most efficient way to deliver training to Ethiopian women farmers from these regions. Mycotoxins trainings were the second option of choice by all women surveyed. Such findings clearly stated the existence of gender inequality in the two Ethiopian regions considered. Empower women’s knowledge about mycotoxins will not only benefit agricultural income and the national economy, but it will also provide women the recognition they equally deserve alongside their male counterparts in future agricultural training programs and interventions.
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    Atoxigenic isolates of Aspergillus flavus effectively reduce cyclopiazonic acid in a sorghum-based matrix under simulated abiotic stress conditions
    (Oxford University Press (OUP), 2025-05-15) Sharma, Vanshika; Cervini, Carla; Verheecke-Vaessen, Carol; Bandyopadhyay, Ranajit; Medina, Angel; Ortega-Beltran, Alejandro; Magan, Naresh
    Maize, groundnut, and sorghum are important staple crops in several countries, but are prone to mycotoxin contamination. In the tropics and subtropics, Aspergillus flavus frequently contaminates those crops with aflatoxins and, sometimes, with cyclopiazonic acid (CPA). However, some genotypes cannot produce one or both toxins. In various countries, atoxigenic isolates of A. flavus are formulated into biocontrol products for field use to outcompete aflatoxin producers. The products effectively limit aflatoxin but their utility to reduce CPA remains unexplored. The abilities of four atoxigenic isolates (AF-) from Burkina Faso to control CPA by an isolate with high capacity to produce aflatoxins (AF+) and CPA was tested in co-inoculations at varying ratios (100+, 75+/25-, 50+/50-, 25+/75-, 100-), under simulated abiotic stress conditions. Experiments were conducted on 2% sorghum-based media at 0.95 and 0.90 water activity (aw), at 30°C and 37°C, for 12 days. CPA was quantified using LC-MS/MS. CPA concentrations gradually decreased as the proportion of atoxigenic isolates increased, with effectiveness varying depending on the environmental conditions.
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    Biocontrol activities of yeasts or lactic acid bacteria isolated from Robusta coffee against Aspergillus carbonarius growth and ochratoxin A production in vitro
    (Elsevier, 2024-04-16) López Rodríguez, Claudia; Strub, Caroline; Fontana, Angélique; Verheecke-Vaessen, Carol; Durand, Noël; Beugré, Corinne; Guehi, Tagro; Medina, Angel; Schorr-Galindo, Sabine
    Biocontrol Agents (BCAs) can be an eco-friendly alternative to fungicides to reduce the contamination with mycotoxigenic fungi on coffee. In the present study, different strains of bacteria and yeasts were isolated from Ivorian Robusta coffee. Their ability to reduce fungal growth and Ochratoxin A (OTA) production during their confrontation against Aspergillus carbonarius was screened on solid media. Some strains were able to reduce growth and OTA production by 85 % and 90 % and were molecularly identified as two yeasts, Rhodosporidiobolus ruineniae and Meyerozyma caribbica. Subsequent tests on liquid media with A. carbonarius or solely with OTA revealed adhesion of R. ruineniae to the mycelium of A. carbonarius through Scanning Electron Microscopy, and an OTA adsorption efficiency of 50 %. For M. caribbica potential degradation of OTA after 24 h incubation was observed. Both yeasts could be potential BCAs good candidates for Ivorian Robusta coffee protection against A. carbonarius and OTA contamination.
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    Biocontrol of ochratoxigenic fungi by endogenous lactic acid bacteria and yeasts from ivorian robusta coffee in the context of climate change
    (Cranfield University, 2023-09) López Rodríguez, Claudia; Medina, Angel; Schorr-Galindo, Sabine; Verheecke-Vaessen, Carol; Fontana, Angelique; Strub, Caroline
    This doctoral research delves into the innovative domain of biocontrol strategies targeting mycotoxigenic fungi in the context of climate change. Focusing on Ivorian coffee, a vital economic and agricultural commodity, the study explores the potential of indigenous lactic acid bacteria (LAB) and yeasts as biocontrol agents. Mycotoxins, toxic secondary metabolites produced by fungi, pose significant health risks and economic losses. As climate change amplifies the proliferation of mycotoxigenic fungi, the demand for sustainable and eco-friendly interventions intensifies. The research encompasses comprehensive isolation, identification, and characterization of LAB and yeasts from Ivorian coffee, evaluating their antagonistic properties against mycotoxigenic fungi. Furthermore, the study elucidates the mechanisms underlying the biocontrol activity, shedding light on how these microorganisms mitigate mycotoxin contamination. This research is pivotal in the pursuit of climate-resilient strategies for mycotoxin management, contributing to both food safety and agricultural sustainability.
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    Biological activities of Streptomyces sp. Bts40 isolated from the rhizosphere of Artemisia herba-alba Asso
    (Universitatea din Oradea, 2022-01-04) Djemouai, Nadjette; Meklat, Atika; Gaceb-Terrak, Rabéa; Oulad Hadj Youcef, Khadidja; Nacer, Asma; Mokrane, Salim; Bouras, Noureddine; Verheecke-Vaessen, Carol
    Actinobacteria isolated from the rhizosphere of plants are of interest as they produce a diverse range of molecules, such as antibiotics and enzymes. This study investigates the antibacterial activity, plant growth-promoting (PGP) abilities as well as the production of extracellular enzymes by the actinobacterial strain BTS40. This strain was isolated from the rhizospheric soil of the medicinal plant Artemisia herba-alba Asso that was naturally grown in a semi-arid environment. Morphological characteristics showed that the strain BTS40 belongs to the genus Streptomyces. Analysis of BTS40’s 16S rRNA gene sequence showed 99.45% similarity to Streptomyces alboniger NRRL B-1832T, in the EzTaxon database. This actinobacterium showed only antibacterial activity against Gram-positive bacteria. The strain also showed potential multiple traits for plant growth promotion and hydrolysis of enzymes. Hence, this study reveals that strain BTS40 has multiple PGP traits and produces many extracellular hydrolytic enzymes.
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    Biovalorisation of crude glycerol and xylose into xylitol by oleaginous yeast Yarrowia lipolytica
    (BMC (part of Springer Nature), 2020-06-03) Prabhu, Vinayak Ashok; Thomas, Dominic J.; Ledesma-Amaro, Rodrigo; Leeke, Gary A.; Medina, Angel; Verheecke-Vaessen, Carol; Coulon, Frederic; Agrawal, Deepti; Kumar, Vinod
    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.
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    Carbon dioxide production as an indicator of Aspergillus flavus colonisation and aflatoxins/cyclopiazonic acid contamination in shelled peanuts stored under different interacting abiotic factors
    (Elsevier, 2019-10-24) Garcia Cela, Esther; Gari Sanchez, F. J.; Sulyok, Michael; Verheecke-Vaessen, Carol; Medina, Angel; Kruska, Rudolf; Magan, Naresh
    Aspergillus flavus is the main xerophylic species colonising stored peanuts resulting in contamination with aflatoxins (AFs) and cyclopiazonic acid (CPA). This study evaluated the relationship between storage of shelled peanuts under interacting abiotic conditions on (a) temporal respiration (R) and cumulative CO2 production, (b) dry matter losses (DMLs) and (c) aflatoxin B1 (AFB1) and CPA accumulation. Both naturally contaminated peanuts and those inoculated with A. flavus were stored for 7-days under different water activities (aw; 0.77–0.95) and temperatures (20–35°C). There was an increase in the temporal CO2 production rates in wetter and warmer conditions, with the highest respiration at 0.95 aw + A. flavus inoculum at 30°C (2474 mg CO2kg−1h−1). The DMLs were modelled to produce contour maps of the environmental conditions resulting in maximum/minimum losses. Maximum mycotoxin contamination was always at 0.95 aw although optimal temperatures were 25-30°C for AFs and 30-35°C for CPA. These results showed a correlation between CO2 production and mycotoxin accumulation. They also provide valuable information for the creation of a database focused on the development of a post-harvest decision support system to determine the relative risks of contamination with these mycotoxins in stored shelled peanuts.
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    Cladosporium species: the predominant species present on raspberries from the U.K. and Spain and their ability to cause skin and stigmata infections
    (MDPI, 2023-01-17) Farwell, Lauren Helen; Deakin, Greg; Harris, Adrian Lee; Fagg, Georgina; Passey, Thomas; Verheecke-Vaessen, Carol; Magan, Naresh; Xu, Xiangming
    Raspberry (Rosales: Rosaceae) production in the U.K. has moved rapidly in the last 10 years to under polythene, combined with a reduced availability of broad-spectrum fungicides. Hence, the incidence of previously less prevalent diseases, such as Cladosporium (Capnodiales: Cladosporiaceae), has largely increased. This study aimed to identify the predominant Cladosporium species on raspberry and to understand the nature of its infection on raspberry fruit. Raspberries were collected from farms across the U.K. and Spain and incubated; fungal isolates were then isolated from typical Cladosporium lesions and identified to the species level based on the sequences of the trans elongation factor α and actin genes. Cladosporium cladosporioides (Fres) de Vries was confirmed as the predominant species responsible for infecting raspberry fruit close to harvest on fruit from the U.K. and Spain, being present on 41.5% of U.K. fruit and 84.6% of Spanish fruit. Raspberries were subsequently inoculated at different developmental stages with C. cladosporioides isolates to determine the susceptibility to Cladosporium skin lesions and stigmata infections in relation to the developmental stage. Only the ripening and ripe raspberries were susceptible to Cladosporium, resulting in skin lesions. Cladosporium can colonise the stigmata of raspberries earlier in fruit development and future research is required to determine if such stigmata infections could cause subsequent skin lesion infections. This study has provided the necessary epidemiological information to develop effective management measures against the Cladosporium species.
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    Dataset "Effect of temperature, relative humidity and incubation time on the mycotoxin production by Fusarium spp. responsible for dry rot in potato tubers"
    (Cranfield University, 2024-08-01) Verheecke-Vaessen, Carol
    Potato is the fourth most consumed crop around the world. More than half of the potato crop is stored for three to nine months at cold temperatures (3- 10°C) for the fresh and seed market. One of the main causes of fresh potato waste in the retail supply chain is the appearance of fungal and bacterial rots during storage, around 3-5% of the potato crop is lost every year. Dry rot is a fungal disease that mainly affects the potato crop during storage and is responsible for a large volume of waste and associated economic losses. It is produced by Fusarium spp., such as Fusarium sambucinum and F. oxysporum. Understanding the ecophysiology of these fungi is a key point to mitigate their occurrence under commercial storage conditions. Therefore, this work aimed to elucidate the effect of three different temperatures (5, 10 and 15°C) and two different water activities (aw; 0.97, 0.99) on the ecophysiology and mycotoxin accumulation of F. sambucinum and F. oxysporum in a potato-based semi-synthetic medium. The mycotoxin accumulation was then studied in vivo, in potato tubers stored for 40 days at 8.5°C. Results showed that higher temperatures and aw enhanced fungal growth, lag time and mycotoxin accumulation in vitro. Six different mycotoxins (r-2, HT-2, diacetoxyscirpenol, 15-acetoxyscirpenol, neosolaniol and beau-vericin) were detected in vitro and in vivo. Due to the long period of time that potato tubers spend in storage, the fluctuations of environmental factors, such as temperature and relative humidity, could promote the development of fungal rots, as well as mycotoxin accumulation. This could result in important food and economical losses for the potato market, as well as a threat to the food safety of potato tubers
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    Diversity and bioactivity of endophytic actinobacteria associated with the roots of artemisia herba-alba asso from Algeria
    (Springer , 2024-12-01) Djemouai, Nadjette; Meklat, Atika; Youcef, Khadidja Oulad Hadj; Nacer, Asma; Saadi, Sid Ahmed; Verheecke-Vaessen, Carol
    The isolation of endophytic actinobacteria from the roots of wild populations of Artemisia herba-alba Asso, a medicinal plant collected from the arid lands of Algeria, is reported for the first time. Forty-five actinobacterial isolates were identified by molecular analysis and in vitro evaluated for antimicrobial activity and plant growth-promoting (PGP) abilities (1-Aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, nitrogen fixation, phosphate and potassium solubilization, ammonia, and siderophores production). The phylogenetic relationships based on 16S rRNA gene sequences show that the genus Nocardioides (n = 23) was dominant in the sampled localities. The remaining actinobacterial isolates were identified as Promicromonospora (n = 11), Streptomyces (n = 6), Micromonopora (n = 3), and Saccharothrix (n = 2). Only six (13.33%) strains (five Streptomyces and one Saccharothrix species) were antagonistic in vitro against at least one or more indicator microorganisms. The antimicrobial activity of actinobacterial strains targeted mainly Gram-positive bacteria. The results demonstrate that more than 73% of the isolated strains had ACC deaminase activity, could fix atmospheric nitrogen and were producers of ammonia and siderophores. However, only one (2.22%) strain named Saccharothrix sp. BT79 could solubilize phosphorus and potassium. Overall, many strains exhibited a broad spectrum of PGP abilities. Thus, A. herba-alba provides a source of endophytic actinobacteria that should be explored for their potential biological activities.
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    Dynamics of solute/matric stress interactions with climate change abiotic factors on growth, gene expression and ochratoxin aA production by Penicillium verrucosum on a wheat-based matrix
    (Elsevier, 2020-10-16) Abdelmohsen, Shaimaa; Verheecke-Vaessen, Carol; García-Cela, Esther; Medina, Angel; Magan, Naresh
    Penicillium verrucosum is responsible for ochratoxin A (OTA) contamination of temperate cereals during harvesting and storage. Inoculum comes from soil and crop debris. This study examined the effect of temperature (25 vs 30 °C), CO2 (400 vs 1000 ppm) and matric and 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 °C, regardless of CO2 concentrations. At 30 °C, 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, the growth patterns under solute stress was slower in elevated CO2 than under matric stress conditions 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.
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    Effect of post-harvest management practices on the mycobiome and ochratoxin A contamination of differently processed Robusta coffees from Ivory Coast
    (Elsevier, 2023-09-15) López Rodríguez, Claudia; Strub, Caroline; Chochois, Vincent; Verheecke-Vaessen, Carol; Durand, Noël; Jourdan, Christophe; Fontana, Angélique; Guehi, Tagro; Medina, Angel; Schorr-Galindo, Sabine
    Ochratoxin A (OTA) is a secondary metabolite produced primarily by the genus Aspergillus sp. sections Circumdati and Nigri. It can accumulate in coffee at post-harvest stage. In the present study five different dry processed coffees were sampled from Ivory Coast at harvesting and after drying. The OTA was detected in all the samples, from 3.62 μg/kg of coffee just after harvest to a higher-level of contamination in the dried coffee, between 11.04 and 760.24 μg/kg of coffee. Metabarcoding was used to further study the changes in the mycobiota. The alpha and beta diversity analysis revealed the presence of unique and more diverse fungal communities on the coffee after drying compared to fresh harvested coffee. Specially, coffee dried for a longer period showed a higher diversity. Fungal species such as Hypopichia sp. or Bernettozyma sp., were replaced in the top ten abundant species after drying by species such as Kurtzmaniella sp., Meyerozyma sp. and Fusarium sp. The increasing abundance of the ochratoxigenic fungi, A. carbonarius was correlated to the increased concentration of OTA on coffee. The construction of the negative correlation network shows that some yeasts could be good candidates for the biocontrol of A. carbonarius. The combination of DNA metabarcoding and OTA quantification was effective at deciphering the post-harvest origin of the OTA contamination. Overall, this study highlights the changes in the mycobiota under different drying conditions. Future perspectives include developing actions of prevention and control of the contamination with OTA during the post-harvest stages.
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    Effect of temperature, relative humidity, and incubation time on the mycotoxin production by Fusarium spp. responsible for dry rot in potato tubers
    (MDPI, 2024-10-01) Gutiérrez-Pozo, Maria; Verheecke-Vaessen, Carol; Kourmpetli, Sofia; Terry, Leon A.; Medina, Angel
    Potato is the fourth most consumed crop in the world. More than half of the crop is stored for three to nine months at cold temperatures (3–10 °C) for the fresh and seed market. One of the main causes of fresh potato waste in the retail supply chain is the processing of fungal and bacterial rots during storage. Dry rot is a fungal disease that mainly affects the potato crop during storage and is responsible for 1% of tuber losses in the UK. It is produced by Fusarium spp., such as Fusarium sambucinum and F. oxysporum, which can lead to the accumulation of mycotoxins in the potato tuber. Little is known about the impact of environmental factors on the accumulation of mycotoxins in potato tubers. Understanding the ecophysiology of these fungi is key to mitigating their occurrence under commercial storage conditions. Therefore, this work aimed to elucidate the effect of three different temperatures (5, 10, and 15 °C) and two different water activities (aw; 0.97, 0.99) on the ecophysiology and mycotoxin accumulation of F. sambucinum and F. oxysporum in a potato-based semi-synthetic medium. The mycotoxin accumulation was then studied in vivo, in potato tubers cultivated under organic farming conditions, stored for 40 days at 8.5 °C. Results showed that higher temperatures and aw enhanced fungal growth, lag time, and mycotoxin accumulation in vitro. Growth rate was 2 and 3.6 times higher when the temperature increased from 5 to 10 and 15 °C, respectively. Six different mycotoxins (T-2, HT-2, diacetoxyscirpenol, 15-acetoxyscirpenol, neosolaniol, and beauvericin) were detected in vitro and in vivo. T-2 was the most abundant mycotoxin detected in vitro, observing 106 ng of T-2/g media after 21 days of incubation at 10 °C and 0.99 aw. Due to the long period of time that potato tubers spend in storage, the fluctuations of environmental factors, such as temperature and relative humidity, could promote the development of fungal rot, as well as mycotoxin accumulation. This could result in important food and economic losses for the potato market and a threat to food safety.
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    Essential oils modulate gene expression and ochratoxin a production in Aspergillus carbonarius
    (MDPI, 2016-08-19) El Khoury, Rachelle; Atoui, Ali; Verheecke-Vaessen, Carol; Maroun, Richard; El Khoury, André; Mathieu, Florence
    Ochratoxin A (OTA) is a mycotoxin, mainly produced on grapes by Aspergillus carbonarius, that causes massive health problems for humans. This study aims to reduce the occurrence of OTA by using the ten following essential oils (E.Os): fennel, cardamom, anise, chamomile, celery, cinnamon, thyme, taramira, oregano and rosemary at 1 µL/mL and 5 µL/mL for each E.O. As a matter of fact, their effects on the OTA production and the growth of A. carbonarius S402 cultures were evaluated, after four days at 28 C on a Synthetic Grape Medium (SGM). Results showed that A. carbonarius growth was reduced up to 100%, when cultured with the E.Os of cinnamon, taramira, and oregano at both concentrations and the thyme at 5 µL/mL. As for the other six E.Os, their effect on A. carbonarius growth was insignificant, but highly important on the OTA production. Interestingly, the fennel E.O at 5 µL/mL reduced the OTA production up to 88.9% compared to the control, with only 13.8% of fungal growth reduction. We further investigated the effect of these E.Os on the expression levels of the genes responsible for the OTA biosynthesis (acOTApks and acOTAnrps along with the acpks gene) as well as the two regulatory genes laeA and vea, using the quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) method. The results revealed that these six E.Os reduced the expression of the five studied genes, where the ackps was downregulated by 99.2% (the highest downregulation in this study) with 5 µL/mL of fennel E.O. As for the acOTApks, acOTAnrps, veA and laeA, their reduction levels ranged between 10% and 96% depending on the nature of the E.O and its concentration in the medium.
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    Exploration of actinobacteria communities in seawater and sediments of mediterranean basin from Algerian coast displays hight diversity with new taxa and antibacterial potential
    (Springer, 2023-02-20) Matmoura, Amina; Yekkour, Amine; Boufadi, Mokhtaria Yasmina; Bouras, Noureddine; Zitouni, Abdelghani; Mokrane, Salim; Meklat, Atika; Verheecke-Vaessen, Carol
    The biodiversity of actinobacteria in the Mediterranean Sea habitat has drawn limited attention compared to that paid to terrestrial habitats. The work presented here focused on the biodiversity of culturable marine actinobacteria from sediments and seawater collected from the Algerian coast, and led to the identification of 114 actinobacterial isolates. The morphological study revealed higher actinobacterial diversity in sediment than in seawater. Fifty strains were selected for 16 S rRNAgene sequencing. The results revealed that the isolates belonged to ten different genera, Streptomyces (n = 17) and Micromonospora (n = 15) being the most dominant. The remaining actinobacterial isolates, identified as belonging to rare genera, included Nocardia (n = 5), Nocardiopsis (n = 3), Saccharothrix (n = 2), Rhodococcus (n = 2), Promicromonospora (n = 2), Nonomuraea (n = 2), Actinomadura (n = 1) and Saccharomonospora (n = 1). Interestingly, through 16 S rRNA sequence-based identification and phylogenetic analysis, two strains of the genus Streptomyces (MAT1 and MAS22) and a strain of the genus Nonomuraea (MAG8) both constituted a novel species. Screening of antibacterial activity of identified isolates against a panel of human pathogenic bacteria demonstrated that 36% of the isolates were active, particularly against Gram-positive bacteria. The ability to grow in the presence of NaCl and seawater revealed that 98% of the strains were halotolerant, with different levels of NaCl acceptance (from 3 to 13%) but no isolates required seawater to grow.
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    Genome‐wide association mapping of Fusarium langsethiae infection and mycotoxin accumulation in oat (Avena sativa L.)
    (Wiley, 2020-06-08) Isidro-Sánchez, Julio; Cusack, Kane D’Arcy; Verheecke-Vaessen, Carol; Kahla, Amal; Bekele, Wubishet; Doohan, Fiona; Magan, Naresh; Medina, Angel
    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.
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    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) García-Cela, Esther; Verheecke-Vaessen, Carol; Ósk-Jónsdóttir, Inga; Lawson, Rita; Magan, Naresh
    Fusarium 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.
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    Harvest and post-harvest handling practices associated with Fumonisin B1 Contamination in maize (Zea mays L.): dietary exposure and risk characterization in Eastern Ethiopia
    (Springer, 2022-09-30) Mohammed, Abdi; Seid, Awol; Terefe, Habtamu; Cervini, Carla; Verheecke-Vaessen, Carol
    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 1058 μg/kg ± 234 in the Kersa district while a minimum of 22.60 μg/kg ± 5.27 in Meta. In flour samples, the maximum FB1 (327 μg/kg) was detected from the Oda Bultum district. The maximum exposure of infants was estimated at Kersa (1131 µg/kg bw/day), followed by Oda Bultum (1073 µg/kg bw/day) and Haramaya (854 µg/kg bw/day). Overall, FB1 exposures ranged from 6.09 to 1131 µg/kg bw/day, which is 3 to 500 µg/kg bw/day higher than the maximum tolerable daily intake of 2 µg/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.