Browsing by Author "Gutierrez-Pozo, Maria"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Open Access 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, FionaOats 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).Item Open Access Identification of volatile organic compounds (vocs) as biomarkers of potato rots during cold storage and ecophysiological study of the pathogens involved.(Cranfield University, 2021-03) Gutierrez-Pozo, Maria; Medina-Vayá, Ángel; Kourmpetli, Sofia; Terry, Leon A.Potato tubers are stored for up to ten months. Therefore, controlling the conditions (temperature and relative humidity) in the storage environment is essential to reduce the risk of appearance of potato diseases. Fluctuations in the environmental conditions appear throughout the storage room, allowing the development of potato rots. This work aimed to identify Volatile Organic Compound (VOC) biomarkers of potato diseases to achieve an early identification of potato rots under commercial storage conditions. Furthermore, to achieve a deep understanding of the ecophysiology of the fungal and bacterial pathogens involved. Some of the objectives of this study were the isolation of fungal pathogens from potato tubers, the study of the mycotoxin production in the presence of dry rot, the development of a methodology for the VOC sampling and identification, and the study of the effect of storage time on the potato susceptibility to dry rot and soft rot. A method for the untargeted detection and identification of VOCs produced by potatoes during storage was developed using Thermal Desorption-Gas Chromatography-Time of Flight- Mass Spectrometry. A range of different TD (Thermal desorption) tubes were evaluated, and the most suitable for the adsorption of VOCs under the study conditions were selected. An in vitro study of the pathogens responsible for gangrene and dry rot was carried out using Natural Potato Dextrose Agar (PDA) and three different temperatures (5,10 and 15ᴼC) and water activities (aw) (0.97, 0.98, 0.99). Higher temperature and aw resulted in higher growth rate and lag time of both pathogens, Fusarium spp. and Boeremia foveata. Furthermore, mycotoxins, such as T-2, HT- 2, diacetoxyscirpenol, beauvericin and neosolaniol, were detected in potato tubers infected with dry rot. An in vivo study of dry rot and soft rot was carried out at 8.5ᴼC, using two cultivars with different susceptibility to these diseases (cvs. Record and Casablanca). The internal and external lesions resulting from the infection were assessed over time and the VOC fingerprint of each cultivar at each time point was determined. The effect of storage time on the disease severity was also evaluated, demonstrating that at 8.5ᴼC, only dry rot’s severity was affected by the longer storage time, while no effect was observed in soft rot. Several VOCs were detected in higher abundance in presence of the pathogen in the in vivo and in vitro studies. They were selected as potential biomarkers of dry rot, soft rot and gangrene. Ethanol, acetone, ethyl acetate and acetic acid were detected in vitro as potential indicators of the presence of a fungal or bacterial disease. Furthermore, 2-methylpropan-1-ol was selected as a potential indicator of the presence of a fungal pathogen, such as Fusarium spp., responsible for dry rot in potato tubers. In vivo, 1-methoxy-3-methylbutane, 2- butanone, dimethyl disulfide and hydrogen cyanide were detected as potential biomarkers of dry rot or soft rot in potato tubers. Lastly, based on the findings that have been achieved in this work, future research should be focused on the study of the growth and VOC production of Pectobacterium carotovorum spp. in vitro and the study of the disease severity and VOC production of gangrene in vivo. Furthermore, a validation of the VOC results achieved in this work under commercial storage conditions should be carried out. These studies will confirm and enhance the findings achieved in this work.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.