Étude physiologique de streptomyces pristinaespiralis producteur de pristinamycines : activités enzymatiques du métabolisme central et mesure du Ph intracellulaire

Abstract : In the last decade, a new rational strategy for fine optimization of industrial interest metabolites production has been achieved by means of metabolic engineering. This field does not only limits to ponctual genomic manipulations in the producing cells, but requires a deeper insight of their phisiology. In this context, a part of carbohydrate (glucose) metabolism in the pristinamycins producing Streptomyces pristinaespiralis has been investigated during trophophase and idiophase. Specific activities for some enzymes belonging to the central metabolism were assayed during batch cultures and showed a general diminution before the antibiotic being excreted. Another basic physiological parameter is the intracellular pH (pHi), which not only affects enzymatic activities but also provides informations about intracellular metabolism. A novel method for its determination has been developped by means of epifluorescence microscopy combined to image analysis. pHi during batch fermentations undergone severe fluctuations correlated to pristinamycins production and succinate and lactate excretions. Finally all parameters measurements were performed during different dilution rates chemostat. Cyclic productions of pristinamycins were observed due to the pristinamycins repression on their own synthesis. This study aUowed quantification of enzymatio contents for different growth rates of non producing cells and revealed pHi changes of a lesser magnitude.
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Philippe Corvini. Étude physiologique de streptomyces pristinaespiralis producteur de pristinamycines : activités enzymatiques du métabolisme central et mesure du Ph intracellulaire. Sciences agricoles. Institut National Polytechnique de Lorraine, 2000. Français. ⟨NNT : 2000INPL111N⟩. ⟨tel-01750398⟩

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