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Criblage, identification et caractérisations physico-chimiques d'exopolysaccharides de microalgues et Cyanobactéries

Abstract : The main objective of this thesis was to improve knowledge on the capacity of microalgae and Cyanobacteria to produce Exopolysaccharides (EPS). Screening carried out on 166 strains from the Roscoff Culture Collection (RCC) made it possible to identify 45 new potentially EPS producers. Biochemical studies using High Performance Anion Exchange Chromatography with a Pulsed Amperometric Detector (HPAEC-PAD), and Gas Chromatography with Mass Spectrometry (GC/MS) confirmed the polysaccharide nature of 20 new identified polymers. During this work, cultures in 1,4 and 5 L Photobioreactors (PBR) were performed on few strains in order to characterize at best their EPS (biochemical compositions and physicochemical characteristics). This word led, in addition, to the identification of a heteroxylan from the microalga Glossomastix. Its EPS consists of a main chain of β-(1,3)- and β-(1,4)-d-Xylp substituted in O-2 and O-3 positions by various chains and/or terminal residues such as d-Xylp-(1→6)-d-Galp, d-Xylp-(1→4)-d-Galp, d-Xylp-(1→3)-d-Galp, Galp-(1⟶SF-Xylp-(1⟶Xylp-(1⟶Glcp-(1⟶. Finally statistical analyzes carried out on 81 monosaccharide compositions of microalgae EPS made it possible for the first time to establish a link between biochemical composition and phylogenetic membership of microalgae.
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Submitted on : Monday, July 25, 2022 - 5:04:46 PM
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Clément Gaignard. Criblage, identification et caractérisations physico-chimiques d'exopolysaccharides de microalgues et Cyanobactéries. Biochimie [q-bio.BM]. Université Clermont Auvergne [2017-2020], 2019. Français. ⟨NNT : 2019CLFAC067⟩. ⟨tel-03738066⟩

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