Etude cinétique de la fermentation glutamique par corynebacterium glutamicum et caractérisation physiologique par cytométrie en flux

Abstract : The aims of this work were to study the parameters which induce the orientation of the metabolism of Corynebacterium glutamicum towards glutamate production and the characterize the physiological events following Tween auddition. In a first part, a performant synthetic medium was developed to achieve high concentration of glutamic acid : 85 g/l. We investigated the effect of severals important parameters. Indeed, this culture needs high oxygenation in order to avoid lactate production and high glycine betaine concentration in order to obtain high production of glutamate. Finally, we showed that osmotic pressure was the most interesting factor. It has been found that an intermediate initial osmotic pressure, around 1200 mosm.kg-1 led to a maximal final concentration of glutamic acid. In the second part, flow cytometry has been used to study cellular physiology. It has been shown that membrane potential, intracellular pH and viability were strongly subjected to the addition of surfactant. For example, surfactant was found to directly act on membrane potential. Tween addition led to an immediate decrease of membrane potential. Besides, we observed that membrane potential decrease raised in proportion to the amount of Tween added. Besides, intracellular pH decreased continuously all over the glutamate producing phase as well as esterases activity and membrane intergrity. In conclusion, flow cytometry represents a good tool for the understanding of the physiology of coryneform bacteria producing glutamic acid
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Theses
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http://docnum.univ-lorraine.fr/prive/INPL_T_1997_DEBAY_F.pdf
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Submitted on : Thursday, March 29, 2018 - 1:40:58 PM
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Florence Debay. Etude cinétique de la fermentation glutamique par corynebacterium glutamicum et caractérisation physiologique par cytométrie en flux. Autre. Institut National Polytechnique de Lorraine, 1997. Français. ⟨NNT : 1997INPL024N⟩. ⟨tel-01752320⟩

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