Effect of Carbon Sources on Glutamate Production from Corynebacterium glutamicum 2262

A comparative study between natural and synthetic environments is carried out by realizing six fermentation experiments in batch culture. The objective of this study is to consider the effect of carbon sources on growth and the production of glutamic acid by Corynebacterium glutamicum 2262. The difference between the culture media lies in the carbon source. Two natural environments of date juice, one of which is treated with invertase to hydrolyse sucrose with a concentration of total sugars of 88 g/L. Four synthetic media with a concentration of 34 g/L sugars: medium containing mixed sugars (glucose + fructose + sucrose) with rates proportional to that of date juice, the other three media are composed of a single sugar (either glucose, fructose, or sucrose). The results showed that Corynebacterium glutamicum is able to use the three sugars whether they are single or mixed, although the best results of glutamate production (8.41 g/L) are obtained on the mixture of three sugars, which explains the interest and valorisation of date waste. On the other hand, the date juice-based media are shown to have a glutamate concentration of 7.98 g/L during the hydrolysis of sucrose of date juice

Utilization of prickly pear waste for baker's yeast production

The feasibility of baker's yeast production using fruits and peels of Opuntia ficus indica (OFI) as carbohydrate feedstock was investigated. Two response surface methodologies involving central composite face centered design (CCFD) were successfully applied. The effects of four independent variables on baker's yeast production from OFI fruit juice was evaluated using the first CCFD. The best results were obtained with 24 H of inoculum age, 30 degrees C temperature, 200 rpm of agitation, and 10% inoculum size. At the maximum point, the biomass concentration reached 9.29 g/L. A second CCFD was performed to optimize the sugar extraction from OFI fruit peels. The potential of these latter as a fermentation substrate was determined. From the experimental results, the OFI fruit peel is an appropriate carbon source for the production of baker's yeast. The maximum biomass concentration was 12.51 g/L. Different nitrogen supplements were added to promote the yields of baker's yeast. Corn steep liquor was found to be the best alternative nutrient source of casein hydrolysate and yeast extract for baker's yeast production.info:eu-repo/semantics/publishedVersio

Production d'acide lactique par Lactobacillus casei subsp. rhamnosus sur jus de datte (cinétique et optimisation en cultures discontinues, semi-continues et continues)

L objectif de ce travail a été de développer un procédé performant de production d acide lactique par Lactobacillus casei subsp. rhamnosus sur jus de datte. Dans une première partie, des cultures en mode discontinu ont été réalisées afin d étudier les besoins nutritionnels de la souche. Ces études ont pour but de décrire les effets des sources carbonées, azotées et les vitamines sur la production d acide lactique. Nous avons montré que le sulfate d ammonium est une bonne alternative économique et nous avons pu déterminer la faisabilité de minimiser l ajout de l extrait de levure par l utilisation partielle de l extrait de levure combinée avec du sulfate d ammonium plus l ajout de vitamines du groupe B. Des cultures pures et mixtes de Lactobacillus casei et Lactococcus lactis ont été réalisées. Le système de culture mixte donne de meilleurs résultats concernant la production d acide lactique et l utilisation des sucres comparés à ceux obtenus en cultures pures de Lactobacillus casei ou Lactococcus lactis. L effet des sucres purs (glucose et fructose) et mixtes (glucose/fructose) sur la production d acide lactique a été étudié. La production d acide lactique est plus importante avec un mélange de sucres qu avec des sucres non mélangés ce qui explique les performances de fermentation sur jus de datte. Dans une seconde partie, une stratégie d alimentation du réacteur en culture semi-continue a été mise en œuvre, permettant d améliorer les performances de la fermentation. Les deux facteurs influençant le bon fonctionnement sont le débit et la concentration du milieu d alimentation. Dans une troisième partie, une étude cinétique a été développée en réacteurs continus. Nous avons étudié l influence du taux de dilution sur la croissance, l utilisation du substrat et la production d acide lactique. La productivité du procédé continu a été considérablement augmentée en comparaison avec le procédé discontinu. Enfin, dans une dernière partie, un modèle a été établi. Ce modèle, bien qu imparfait, permet apparemment de simuler la croissance, la consommation des sucres de jus de datte et la production d acide lactique en culture discontinueThe aim of this work was to develop an efficient process of lactic acid production by Lactobacillus casei subsp. rhamnosus on date juice In a first part, the batch cultures were realized to carry out the nutritional requirement of the strain. These studies allowed us to describe the effects of carbon substrates, nitrogen substrates and vitamins on the lactic acid production. We showed that ammonium sulphate is a satisfying economic alternative and we have determined feasibility of minimizing the addition of the yeast extract by the partial use of yeast extract combined with the ammonium sulphate plus the addition of vitamins of the group B. Pure and mixed cultures of Lactobacillus casei and Lactococcus lactis were carried out. The mixed system gives better results concerning the lactic acid production and the use of the sugars compared with those obtained in pure cultures of Lactobacillus casei or Lactococcus lactis. The effect of pure sugars (glucose and fructose) and mixed sugars (glucose/fructose) on the lactic acid production was studied. The lactic acid production is more important on mixed sugars than on pure sugars what explains the performances of fermentation on date juice. In a second part, a mode of fed batch operations was defined to improve the performances of the fermentation. The two factors influencing the process are the feeding rate and the concentration of the feeding medium. In a third part, kinetic study in continuous culture was developed. We studied the influence of dilution rate on growth, substrate utilization and lactic acid production. The productivity of the continuous process was considerably increased in comparison with the batch process. Finally, a tentative model has been established for the fermentation process. The corresponding model, although not perfect, is apparently able to simulate growth rate, substrates uptake and lactic acid production in batch cultureNANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF

Expression et caractérisation de la phosphate alcaline de l'Euryarchaeote Hyperthermophile Pyrococcus abyssi

NANCY/VANDOEUVRE-INPL (545472102) / SudocSudocFranceF

MODELISATION DE L'INSTABILITE PLASMIDIQUE SEGREGATIONNELLE DE SOUCHES RECOMBINEES (APPLICATION A ESCHERICHIA COLI)

NANCY1-SCD Pharmacie-Odontologie (543952101) / SudocSudocFranceF

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