Browsing by Author "Mathieu, Florence"

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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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    Incidence of mycobiota and aflatoxin B1 in Algerian feed
    (Inderscience, 2022-03-29) Bouti, Karima; Mimoune, Nouara Ait; Mokrane, Salim; Djemouai, Nadjette; Verheecke-Vaessen, Carol; Mathieu, Florence; Riba, Amar
    The presence of fungi and aflatoxin B1 (AFB1) in 101 animal feed samples randomly collected from different vendors and factories in Algeria was investigated. For fungi, the main genera isolated were Aspergillus, Penicillium and Fusarium. Furthermore, the 459 strains of Aspergillus section Flavi were screened for their ability to produce aflatoxins and cyclopiazonic acid. 49% of the strains produced AFB1. The highest incidence of aflatoxigenic strains was recorded in maize (61%) and ground poultry feed (60%). The presence of AFB1 in feed samples was evaluated using HPLC-FLD. The obtained data showed that 36.6% of samples were contaminated in the range of 0.34 to 171.06 μg/kg. Six samples exceeded the Algerian maximum limit of 20 µg/kg for AFB1. This study highlights the potential presence of aflatoxigenic strains belonging to section Flavi and AFB1 in animal feed at post-harvest in Algeria, strategic information for the Algerian policies makers.
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    Polyphasic characterization of Aspergillus section Flavi isolated from animal feeds in Algeria
    (Wiley, 2019-12-13) Bouti, Karima; Verheecke-Vaessen, Carol; Mokrane, Salim; Meklat, Atika; Djemouai, Nadjette; Sabaou, Nasserdine; Mathieu, Florence; Riba, Amar
    In Algeria, little information is available on the population structure of Aspergillus section Flavi in raw materials and resultant animal feeds. A total of 172 isolates belonging to Aspergillus section Flavi were recovered from 57 animal feeds and identified on the basis of macro and micro‐morphological characters, mycotoxin production and genetic relatedness. For the molecular analysis, sequencing of the calmodulin gene (CaM) and the internal transcribed spacer (ITS) regions were performed for representative isolates. Four distinct morphotypes were distinguished: Aspergillus flavus (78.5%), Aspergillus tamarii (19.2%), Aspergillus parasiticus (1.7%), and Aspergillus alliaceus (0.6%). All A. flavus isolates were of the L type and no correlation between sclerotia production and aflatoxigenicity was observed. Our results showed that 68% of the A. flavus strains produced aflatoxins B (AFB), and 72.7% were cyclopiazonic acid (CPA) producers. The three isolates of A. parasiticus were able to produce AFB and aflatoxins G but not CPA whereas, all the strains of A. tamarii produced only CPA. The obtained results revealed the presence of different species of Aspergillus section Flavi, among which were aflatoxin producers. This study provides evidence useful for considerations in aflatoxin control strategies.
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    Taxonomy of mycelial actinobacteria isolated from Saharan soils and their efficiency to reduce aflatoxin B1 content in a solid-based medium
    (Elsevier, 2017-02-02) Lahoum, Abdelhadi; Verheecke-Vaessen, Carol; Bouras, Noureddine; Sabaou, Nasserdine; Mathieu, Florence
    Aflatoxin B1 (AFB1) is a carcinogenic compound produced by filamentous fungi. In order to reduce AFB1 occurrence in foodstuffs, 13 strains of mycelial actinobacteria were tested in vitro for the efficacy to reduce AFB1 content; all were isolated from the Saharan soils of Algeria. Firstly, morphological study and molecular analysis, based on the 16S rRNA gene, indicated that these strains belong to Actinomadura, Nocardiopsis, Nonomuraea, Saccharothrix and Streptomyces genera. Secondly, each strain’s efficacy to reduce pure AFB1 content was studied in ISP2-medium. After a 4-day incubation at 30°C on AFB1-supplemented medium (5 ppm of AFB1), AFB1 was extracted and quantified. AFB1 content was reduced by all strains (42.9–97.6%). The three most efficient reducers (94.9–97.6%) were two strains belonging to the genus Streptomyces and one to the genus Saccharothrix. Among the latter, strains ACD6 and ABH19 showed no adsorption mechanism involved, suggesting a potential degradation mechanism. These findings led us to suggest that these actinobacterial strains could be used as decontamination treatments for the reduction of AFB1 content.