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Charles Diviès - One of the best experts on this subject based on the ideXlab platform.
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The response of Leuconostoc mesenteroides to low external oxidoreduction potential generated by hydrogen gas.
Journal of applied microbiology, 2003Co-Authors: G. Bourel, Charles Diviès, S. Henini, Dominique GarmynAbstract:Aims: The physiological consequences of low external oxidoreduction potential in Leuconostoc mesenteroides were investigated. Methods and Results: Leuconostoc mesenteroides was grown under two initial oxidoreduction potential conditions (E h7 : +200 mV and -400 mV) using nitrogen and hydrogen as reducing agents. Growth was affected by E h7 ; the lag phase increased from 1 h at an initial E h7 of +200 mV to 6 h at an initial E h7 of -400 mV; the maximum specific growth rate at -400 mV was 68% of the one observed at +200 mV. The NADH/NAD + ratio and (NADH + NAD + ) pool were independent of the external E h7 . Conclusions: This study shows that changing the external oxidoreduction potential from +200 to -400 mV has a strong effect on the Leuc. mesenteroides physiology. The constancy of the maximum carbon and energetic fluxes (q glu , q ATP ) under the two E h7 conditions accompanied by the decrease of Y X/S and Y ATP suggested the existence of an uncoupling phenomenon, namely that some catabolized glucose and hence ATP was not associated with biomass production. Significance and Impact of the Study: This paper demonstrates the usefulness of taking into account, the effect of the oxidoreduction potential on the growth of Leuc. mesenteroides in the fermentation process.
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Métabolisme sucre-citrate chez Leuconostoc mesenteroides
Le Lait, 2001Co-Authors: Gérald Bourel, Samia Henini, Kamel Krantar, Mona Oraby, Charles Diviès, Dominique GarmynAbstract:Sugar citrate cometabolism in Leuconostoc mesenteroides. Bacteria from the genus Leuconostocplay roles in the dairy industry. The most important functions of this bacteria are their ability to produce CO 2 and flavour compounds through lactose heterofermentation and citrate uti- lization. Although the biotechnological role of the citrate metabolism is very important and widely appreciated, little is known about the genetic properties of Leuconostoc spp. In our laboratory, we cloned the genes responsible for citrate metabolism ( clyR mae citCDEFGOPcluster), for D-lactate dehydrogenase (ldhD) and for phosphotransacetylase ( pta). In addition we have planned to con- struct new vectors and we have tried to improve a method to introduce recombinant DNA molecules into Leuconostoc as well. Characterization of the plasmid involved in this study is still in progress. The nucleotide sequence analysis of p22R revealed the presence of C5 cytosine methylase gene typ- ical of type II restriction/modification system. The low transformation efficiency of some strains of Leuconostoc may be due to the presence of that plasmid. The construction of the defective strain for restriction activity could be very useful to genetic manipulations of Leuconostocin the future. metabolic engineering / lactic acid bacteria / Leuconostoc mesenteroides / citrate / plasmid / restriction modification
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Métabolisme sucre-citrate chez Leuconostoc mesenteroides
Le Lait, 2001Co-Authors: Gérald Bourel, Samia Henini, Kamel Krantar, Mona Oraby, Charles Diviès, Dominique GarmynAbstract:Sugar citrate cometabolism in Leuconostoc mesenteroides. Bacteria from the genus Leuconostoc play roles in the dairy industry. The most important functions of this bacteria are their ability to produce CO$_2$ and flavour compounds through lactose heterofermentation and citrate utilization. Although the biotechnological role of the citrate metabolism is very important and widely appreciated, little is known about the genetic properties of Leuconostoc spp. In our laboratory, we cloned the genes responsible for citrate metabolism (clyR mae citCDEFGOP cluster), for D-lactate dehydrogenase (ldhD) and for phosphotransacetylase (pta). In addition we have planned to construct new vectors and we have tried to improve a method to introduce recombinant DNA molecules into Leuconostoc as well. Characterization of the plasmid involved in this study is still in progress. The nucleotide sequence analysis of p22R revealed the presence of C5 cytosine methylase gene typical of type II restriction/modification system. The low transformation efficiency of some strains of Leuconostoc may be due to the presence of that plasmid. The construction of the defective strain for restriction activity could be very useful to genetic manipulations of Leuconostoc in the future.
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pH Homeostasis and Citric Acid Utilization: Differences Between Leuconostoc mesenteroides and Lactococcus lactis
Current Microbiology, 1997Co-Authors: Talal Belguendouz, Rémy Cachon, Charles DivièsAbstract:This study presents the effects of citric acid and extracellular pH (pHe) on the intracellular pH (pHi) of wild-type and citrate negative variants (cit−) Leuconostoc mesenteroides subsp. mesenteroides (Ln. mesenteroides M) and Lactococcus lactis subsp. lactis bv. diacetylactis (L. lactis LD). A recent method using a pH-sensitive fluorescent indicator carboxyfluorescein succinimidyl ester (cFSE) was adapted to measure the pHi of these two lactic acid bacteria in resting cells. Energized cells with 10 mM lactose of Ln. mesenteroides M and L. lactis LD modified their pH gradient (ΔpH) in the same manner; when the pHe was decreased from 7 to 4, the pHi decreased from 7 to about 5. The adjunction of 10 mM citric acid had no effect on the pHi of wild-type and cit(−) variant of L. lactis LD, nor on the pHi of Ln. mesenteroides cit(−) variant. Nevertheless, in Ln. mesenteroides M wild-type, citric acid utilization increased the pHi, which was maintained at about 6.5–7.0 when the pHe was decreased from 7 to 4. It could be concluded that citric acid allows the maintenance of pH homeostasis in Leuconostoc mesenteroides.
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Purification and characterization of the catabolic α-acetolactate synthase from Leuconostoc mesenteroides subsp. cremoris
Current Microbiology, 1995Co-Authors: V. Phalip, Philippe Schmitt, Charles DivièsAbstract:The α-acetolactate synthase from Leuconostoc mesenteroides subsp. cremoris was purified to homogeneity in SDS-PAGE. The enzyme is a trimer of 3×55,000 Da. It was unstable but could be preserved by addition of pyruvate and thiamine pyrophosphate in the buffer. The enzyme exhibits Michaelis-Menten kinetics, and Km for pyruvate is 10 mM. Three intermediates in glucose metabolism (ATP, 3-phosphoglycerate, and phosphoenolpyruvate) exhibit a noncompetitive inhibition towards the enzyme. This enzyme does not require any divalent metal ion for activity. The α-acetolactate synthase from Leuconostoc mesenteroides subsp. cremoris is not inhibited by the branched-chain amino acids (valine, leucine, and isoleucine), is FAD independent, and displays an optimal activity at pH 5.3. Therefore, it can be concluded that the purified enzyme belongs to the catabolic α-acetolactate synthases, involved in the 2,3-butanediol pathway but not in branchedchain amino acids biosynthesis.
Dominique Garmyn - One of the best experts on this subject based on the ideXlab platform.
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The response of Leuconostoc mesenteroides to low external oxidoreduction potential generated by hydrogen gas.
Journal of applied microbiology, 2003Co-Authors: G. Bourel, Charles Diviès, S. Henini, Dominique GarmynAbstract:Aims: The physiological consequences of low external oxidoreduction potential in Leuconostoc mesenteroides were investigated. Methods and Results: Leuconostoc mesenteroides was grown under two initial oxidoreduction potential conditions (E h7 : +200 mV and -400 mV) using nitrogen and hydrogen as reducing agents. Growth was affected by E h7 ; the lag phase increased from 1 h at an initial E h7 of +200 mV to 6 h at an initial E h7 of -400 mV; the maximum specific growth rate at -400 mV was 68% of the one observed at +200 mV. The NADH/NAD + ratio and (NADH + NAD + ) pool were independent of the external E h7 . Conclusions: This study shows that changing the external oxidoreduction potential from +200 to -400 mV has a strong effect on the Leuc. mesenteroides physiology. The constancy of the maximum carbon and energetic fluxes (q glu , q ATP ) under the two E h7 conditions accompanied by the decrease of Y X/S and Y ATP suggested the existence of an uncoupling phenomenon, namely that some catabolized glucose and hence ATP was not associated with biomass production. Significance and Impact of the Study: This paper demonstrates the usefulness of taking into account, the effect of the oxidoreduction potential on the growth of Leuc. mesenteroides in the fermentation process.
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Métabolisme sucre-citrate chez Leuconostoc mesenteroides
Le Lait, 2001Co-Authors: Gérald Bourel, Samia Henini, Kamel Krantar, Mona Oraby, Charles Diviès, Dominique GarmynAbstract:Sugar citrate cometabolism in Leuconostoc mesenteroides. Bacteria from the genus Leuconostocplay roles in the dairy industry. The most important functions of this bacteria are their ability to produce CO 2 and flavour compounds through lactose heterofermentation and citrate uti- lization. Although the biotechnological role of the citrate metabolism is very important and widely appreciated, little is known about the genetic properties of Leuconostoc spp. In our laboratory, we cloned the genes responsible for citrate metabolism ( clyR mae citCDEFGOPcluster), for D-lactate dehydrogenase (ldhD) and for phosphotransacetylase ( pta). In addition we have planned to con- struct new vectors and we have tried to improve a method to introduce recombinant DNA molecules into Leuconostoc as well. Characterization of the plasmid involved in this study is still in progress. The nucleotide sequence analysis of p22R revealed the presence of C5 cytosine methylase gene typ- ical of type II restriction/modification system. The low transformation efficiency of some strains of Leuconostoc may be due to the presence of that plasmid. The construction of the defective strain for restriction activity could be very useful to genetic manipulations of Leuconostocin the future. metabolic engineering / lactic acid bacteria / Leuconostoc mesenteroides / citrate / plasmid / restriction modification
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Métabolisme sucre-citrate chez Leuconostoc mesenteroides
Le Lait, 2001Co-Authors: Gérald Bourel, Samia Henini, Kamel Krantar, Mona Oraby, Charles Diviès, Dominique GarmynAbstract:Sugar citrate cometabolism in Leuconostoc mesenteroides. Bacteria from the genus Leuconostoc play roles in the dairy industry. The most important functions of this bacteria are their ability to produce CO$_2$ and flavour compounds through lactose heterofermentation and citrate utilization. Although the biotechnological role of the citrate metabolism is very important and widely appreciated, little is known about the genetic properties of Leuconostoc spp. In our laboratory, we cloned the genes responsible for citrate metabolism (clyR mae citCDEFGOP cluster), for D-lactate dehydrogenase (ldhD) and for phosphotransacetylase (pta). In addition we have planned to construct new vectors and we have tried to improve a method to introduce recombinant DNA molecules into Leuconostoc as well. Characterization of the plasmid involved in this study is still in progress. The nucleotide sequence analysis of p22R revealed the presence of C5 cytosine methylase gene typical of type II restriction/modification system. The low transformation efficiency of some strains of Leuconostoc may be due to the presence of that plasmid. The construction of the defective strain for restriction activity could be very useful to genetic manipulations of Leuconostoc in the future.
Andre De Laporte - One of the best experts on this subject based on the ideXlab platform.
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Optimization of sucrose phosphorylase production by Leuconostoc mesenteroides
Journal of Chemical Technology & Biotechnology, 2007Co-Authors: Erick Vandamme, Jan Van Loo, Eric Simkens, Andre De LaporteAbstract:Environmental optimization of the Leuconostoc mesenteroides ATCC 12291 sucrose phosphorylase fermentation process was undertaken. The effects of pH control, fermentation temperature and medium composition on growth, culture viscosity, sucrose utilization pattern and dynamics of enzyme fermentation were studied. Optimized fermentations were run at controlled pH 7 at 32°C yielding high enzyme levels. Applications of sucrose phosphorylase are discussed.
Erick Vandamme - One of the best experts on this subject based on the ideXlab platform.
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Optimization of sucrose phosphorylase production by Leuconostoc mesenteroides
Journal of Chemical Technology & Biotechnology, 2007Co-Authors: Erick Vandamme, Jan Van Loo, Eric Simkens, Andre De LaporteAbstract:Environmental optimization of the Leuconostoc mesenteroides ATCC 12291 sucrose phosphorylase fermentation process was undertaken. The effects of pH control, fermentation temperature and medium composition on growth, culture viscosity, sucrose utilization pattern and dynamics of enzyme fermentation were studied. Optimized fermentations were run at controlled pH 7 at 32°C yielding high enzyme levels. Applications of sucrose phosphorylase are discussed.
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Polysaccharides, Oligosaccharides, Special Sugars and Enzymes Via Leuconostoc mesenteroides Sp. Fermentations
Lactic Acid Bacteria, 1996Co-Authors: Erick Vandamme, Marc Raemaekers, Nicole Vekemans, Wim SoetaertAbstract:Leuconostoc mesenteroides, a common lactic acid bacterium, displays a wide range of biocatalytic properties, which are potentially useful for industrial carbohydrate modifications. The use of L. mesenteroides for the production of dextran via whole cell fermentation, for leucrose synthesis with dextransucrase, for the synthesis of alternan and gluco-oligosaccharides with alternansucrase, for mannitol fermentation with viable L. mesenteroides cells, and for the synthesis of α-D-glucose- 1 -phosphate using sucrose phosphorylase, are discussed.
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A wide range of carbohydrate modifications by a single microorganism : Leuconostoc mesenteroides
Progress in Biotechnology, 1995Co-Authors: Wim Soetaert, D Schwengers, K Buchholz, Erick VandammeAbstract:Abstract Leuconostoc mesenteroides, a lactic acid bacterium, possesses a wide range of biocatalytic properties that are potentially useful in carbohydrate modifications. The use of L. mesenteroides for production of dextran in whole cell fermentation, enzymatic leucrose synthesis by dextran sucrase, mannitol fermentation with viable L. mesenteroides cells, and the use of sucrose phosphorylase for enzymatic synthesis of α-glucose-1-phosphate from sucrose are discussed. The applications of the various products are also briefly mentioned.
Telma Teixeira Franco - One of the best experts on this subject based on the ideXlab platform.
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Effect of phosphate concentration on the production of dextransucrase by Leuconostoc mesenteroides NRRL B512F.
Bioprocess and biosystems engineering, 2003Co-Authors: Sueli Rodrigues, Liliane M. F. Lona, Telma Teixeira FrancoAbstract:Leuconostoc mesenteroides NRRL B512F is the main strain used in industrial fermentations to produce dextransucrase and dextran. This process has been studied since the Second World War, when it was used as blood plasma expander. A study about the effect of phosphate concentration on cell propagation in a semicontinuous shake-flask culture is described in this work. Dextransucrase is obtained by fermentation of the Leuconostoc mesenteroides NRRL B512F in the presence of sucrose as substrate, a nitrogen source (corn liquor or yeast extract) and minerals. Phosphate is currently used in order to buffer the culture medium. Cell propagation can be done through a repeated batch culture, where dilution in a fresh medium is made with relatively short periods. The standard medium for dextransucrase production is prepared using 0.1 M of K2HPO4. In this work the level of phosphate was increased to 0.3 M, and an increase on biomass and on the enzyme activity was found when phosphate enriched medium was used. Higher phosphate buffer concentration was also able to keep the pH values above 5.0 during the entire process, avoiding enzyme denaturation.