Percorrer por autor "Bejaoui, Hend"
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- Ecophysiology of Penicillium expansum and patulin production in synthetic and olive-based mediaPublication . Hamdi, Mohamed; Bejaoui, Hend; Morais, Jorge Sá; Rodrigues, PaulaOlives and their derivatives, in particular olive oil, represent one of the most significant agricultural products in the Mediterranean basin. Storage under inadequate conditions poses serious problems concerning fungal contamination, with consequent defects and potential mycotoxin production in olives and olive oils. Penicillium expansum represents one of the most significant postharvest pathogens in several fruits, including olives. Not only it causes blue mold but also is one of the most relevant patulin producing species of the genus Penicillium. The aim of this research was to evaluate the ecophysiological conditions governing growth and PAT production by P. expansum strains previously isolated from Tunisian olives. For this purpose, four P. expansum isolates were tested in a synthetic medium (Czapek Yeast Autolysate, CYA) and in olive-based medium (OM) for their ability to grow and produce PAT under different temperatures (4 °C, 15 °C and 25 °C) for 10 and 20 d. The mycotoxin was analysed by HPLC-UV. Results showed that all isolates were able to grow on tested media at different temperatures. Different PAT production profiles were found, showing that at 25 °C P. expansum isolates were able to produce PAT on CYA and OM medium. At 15 °C the production of PAT was only detected on CYA medium, while no PAT production was detected at 4 °C for the two media.
- Ecophysiology of Penicillium expansum and patulin production in synthetic and olive-based mediaPublication . Hamdi, Mohamed; Morais, Jorge Sá; Bejaoui, Hend; Rodrigues, PaulaThe olive and its derivatives, in particular olive oil, represent one of the most significant agricultural products in the Mediterranean basin. Storage under inadequate conditions poses serious problems concerning fungal contamination, with consequent defects and potential mycotoxin production in olives and olive oils. Penicillium expansum represents one of the most significant postharvest pathogens in several fruits, including olives. Not only it causes blue mold but also is one of the most relevant patulin (PAT) producing species of the genus Penicillium. The aim of this research was to evaluate the ecophysiological conditions governing growth and PAT production by P. expansum strains previously isolated from Tunisian olives. For this purpose, four P. expansum isolates were tested in a synthetic medium (Czapek Yeast Autolysate, CYA) and in olive-based medium (OM) for their ability to grow and produce PAT under different temperatures (4 ºC, 15°ºC and 25°ºC) for 10 and 20 days. The mycotoxin was analysed by HPLC-UV. Results showed that all isolates were able to grow on tested media at different temperatures. Different PAT production profiles were found, showing that at 25 ºC P. expansum isolates were able to produce PAT on CYA and OM medium. At 15 ºC the production of PAT was only detected on CYA medium, while no PAT production was detected at 4 ºC for the two media.
- Fungal flora from Tunisian olives carposphere: diversity and volatile organic compoundsPublication . Bejaoui, Hend; Flamini, Guido; Rodrigues, Paula; Mihoubi, NourhènePlant phyllosphere is an enormous environment on Earth densely colonized by microorganisms. Those microbiomes play essential roles in processes related to plant development and pathogen defense. They release different metabolites working as interspecies messages in the environment. Volatile organic compounds are among those released messages. Among the worldwide phyllosphere, oliveyards are widely spread in the Mediterranean basin. Like all foods, olives and oil quality begin in the field. Fungal microbiomes through their interactions with olives trees could have an impact on oil quality. In this work we were interested on fungal microbiomes from olives carposphere. Fifteen Tunisian fields from four climatic regions were studied. Fungi were isolated and identified to species with microscopic and molecular techniques. Their aromatic profiles were analysed by solid-phase micro-extraction (SPME) coupled to gas cromatography and mass spectrometry. Results showed that genus Penicillium (P. polonicum, P. crustosum and P. expansum) was predominant. The major volatiles identified were: Styrene, 1-octen-3-ol, 3-octanol, 3-octanone, 1,8-cineole. Styrene is a volatile hydrocarbon reported as 80 times more toxic than the volatile phase of toluene. The following three are oxylipins. They play essential roles in fungal morphogenesis and pathogenesis and are reported as metabolites with musty and earthy characteristics able to induce mycotoxin production. The last one is a terpene with a eucalyptus herbal camphor odor note. Could those volatiles be found on olives and olive oils? Could they impact chemical and sensory olive oils qualities? Could they induce mycotoxin production in olive oils? All those questions still to be answered…
- Identification of mycobiota from Tunisian olives and determination of their mycotoxigenic profilePublication . Hamdi, Mohamed; Bejaoui, Hend; Rodrigues, PaulaIn the Mediterranean basin, a large number of olive varieties are produced and cultivated. In Tunisia, olive culture represents one of the most significant agricultural products that is produced annually. Storage under inadequate conditions poses serious problems concerning fungal contamination, with consequent defects and potential mycotoxin production in olives and olive oils. In this study, we aimed to identify and characterize a selected group of fungi previously isolated from olives from Tunisian groves. For this purpose, 28 fungi were selected for identification by a polyphasic approach consisting of morphological identification on Malt Extract Agar (MEA) and Czapek Yeast Autolysate (CYA); physiological identification by the Erlich test (for the genus Penicillium only); and molecular identification by sequencing of the ITS region of the rRNA gene. Mycotoxigenic ability of fungi was screened on Coconut Agar Medium (CAM). Methanolic extracts of those fungi showing fluorescence on CAM wereobtained from CYA cultures and analysed by HPLC. From morphological and molecular identification, eight species belonging to the genera Alternaria, Aspergillus, Fusarium, Penicillium, Pleospora and Tricothecium and were identified. Results showed several isolates were able to produce toxins on CAM, by showing green or orange fluorescence. HPLC analysis are being developed.