Production et fractionnement de polysaccharides de levures

Abstract : The aim of this work is to acquire knolewdges on the differents steps of a yeast glycogen production process. In the first part, the influence of several parameters on the glycogen accumulation kinetic have been determined. An increase of the specific glucose consumption rate leads to an increase of the specific glycogen production rate. High level of intracellular glycogen (25 % of dry weight) has been obtained when the specific growth rate was very low. The sugar-to-glycogen yield increases when the production of ethanol is reduced by a low sugar concentration. In the second part, the extraction of yeast glycogen has been studied. A comparison of several yeast cell disintegration methods shows that high pressure homogenization leads to the highest glycogen extraction yield. The efficiency of this method is enhanced by a yeast pre-treatment. This yield is about 90 % when cells are pretreated by heating in the presence of Na2CO3. In the third part, the efficiencies of ultrafiltration and precipitation processes have been evaluated for the purification of glycogen. We have developed an original two steps yeast glycogen purification process. A first step of diafiltration-ultrafiltration leads to an elimintation of 90 % of sakts abd 80 % of nitrogenous material, and a glycogen purity degree of 50 %. A second step of precipitation by HCI leads to an elimination of 70 % remaining nitrogenous material, and a glycogen purity degree of 60 %
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Theses
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http://docnum.univ-lorraine.fr/prive/INPL_T_1997_GENTIL_F.pdf
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https://hal.univ-lorraine.fr/tel-01752322
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Submitted on : Thursday, March 29, 2018 - 1:40:59 PM
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Fabrice Gentile. Production et fractionnement de polysaccharides de levures. Autre. Institut National Polytechnique de Lorraine, 1997. Français. ⟨NNT : 1997INPL099N⟩. ⟨tel-01752322⟩

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