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EVALUATION DU RISQUE FONGIQUE EN ZONES CONCHYLICOLES : SUBSTANCES TOXIQUES DE SOUCHES MARINES DU GENRE Trichoderma.

Abstract : This work is devoted to the chemical study of peptaïbols produced by endemic Trichoderma strains in the Loire-Atlantique shellfish farming areas. The adopted strategy made possible to realize:
 A sampling from the marine fungal collection of SMAB (Substances Marines à Activité Biologique) of Trichoderma strains with peptaibols production in the Loire estuary. Nine representative strains were selected. According to their peptaïbols production, they were divided into 4 sets; a "representative strain" of each set was then selected for next steps.
 The optimization of the used methods for the peptaïbols in vitro production. The development of a fermentation mode on agar medium increases the biosynthesis output.
 An optimization of the peptaibol purification conditions. Simplified methods of pre-purification and purification by high performance liquid chromatography (HPLC) allowed the preparation of analysable samples by mass spectrometry.
 The structural identification of the produced peptaibols by use of mass spectrometry sequencing; electro spray ionisation mode (ESI) and ion trap analyser allowing MSn analysis. The latter make possible the identification of peptaïbols with very similar structures (due to the peptaibols microheterogeneity phenomenon). The use of coupled gas chromatography to mass spectrometry (GC-MS-IE) allows the differentiation of the amino acids (AA) of the same mass (Valine or Isovaline; Leucine or Isoleucine).

Thirty peptaibols produced by the four studied Trichoderma strains were identified. 24 of which, are new molecules and belong to 5 already described families: trichokonines, trichosporines, hypomurocines, trichorovines and suzukacillines. 21 are long sequences peptaïbols (18 to 20 AA) including 16 new structures. Among the 9 remaining peptaïbols with short sequence (11 AA), 8 have enough original structures to enabling us to propose a new peptaibol family: the trichobrachine's.
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https://tel.archives-ouvertes.fr/tel-00087612
Contributor : Mustapha Mohamed-Benkada <>
Submitted on : Tuesday, July 25, 2006 - 9:15:21 PM
Last modification on : Thursday, April 5, 2018 - 10:36:33 AM
Long-term archiving on: : Monday, April 5, 2010 - 10:06:49 PM

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Mustapha Mohamed-Benkada. EVALUATION DU RISQUE FONGIQUE EN ZONES CONCHYLICOLES : SUBSTANCES TOXIQUES DE SOUCHES MARINES DU GENRE Trichoderma.. Sciences pharmaceutiques. Université de Nantes, 2006. Français. ⟨tel-00087612⟩

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