The Experts below are selected from a list of 4869 Experts worldwide ranked by ideXlab platform
Christophe Lacroix - One of the best experts on this subject based on the ideXlab platform.
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continuous production of mixed lactic starters containing probiotics using Immobilized Cell technology
Biotechnology Progress, 2008Co-Authors: Y Doleyres, I Fliss, Christophe LacroixAbstract:The production of a mixed lactic Culture containing Lactococcus lactis subsp. lactis biovar. diacetylactis MD and Bifidobacterium longum ATCC 15707 was studied during a 17-day continuous Immobilized-Cell Culture at different temperatures between 32 and 37 °C. The two-stage fermentation system was composed of a first reactor (R1) containing Cells of the two strains separately Immobilized in κ-carrageenan/locust bean gum gel beads and a second reactor (R2) operated with free Cells released from the first reactor. The system allowed continuous production of a concentrated mixed Culture with a strain ratio whose composition depended on temperature and fermentation time. A stable mixed Culture (with a 22:1 ratio of L.diacetylactis and B. longum) was produced at 35 °C in the effluent of R2, whereas the mixed Culture was rapidly unbalanced in favor of B.longum at a higher temperature (37 °C) or L. diacetylactis at a lower temperature (32 °C). Strain redistribution in beads originally immobilizing pure Cultures of L. diacetylactis or B. longum was observed. At the end of Culture, the strain ratio (7:1 L. diacetylactis/B.longum) in bulk bead samples was similar to that of individual beads. The determination of the spatial distribution of the two strains in gel beads by immunofluorescence and confocal laser-scanning microscopy showed that bead cross-contamination was limited to a 100 μm peripheral layer. Data from this study validate a previous model for population dynamics and Cell release in gel beads during mixed Immobilized-Cell Cultures.
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increased stress tolerance of bifidobacterium longum and lactococcus lactis produced during continuous mixed strain Immobilized Cell fermentation
Journal of Applied Microbiology, 2004Co-Authors: Y Doleyres, I Fliss, Christophe LacroixAbstract:Y. DOLEYRES, I. FLISS AND C. LACROIX. 2004. Aims: The effect of immobilization and long-term continuous Culture was studied on probiotic and technological characteristics of lactic acid and probiotic bacteria. Methods and Results: A continuous Culture in a two-stage system was carried out for 17 days at different temperatures ranging from 32 to 37� C, with a first reactor containing Bifidobacterium longum ATCC 15707 and Lactococcus lactis subsp. lactis biovar. diacetylactis MD Immobilized separately in gel beads, and a second reactor operated with free Cells released from the first reactor. The tolerance of free Cells from both strains produced in the effluent medium of both reactors to hydrogen peroxide, simulated gastric and intestinal juices, antibiotics and nisin, and freeze-drying markedly increased with Culture time and was generally higher after 6 days than that of stationary-phase Cells produced during free-Cell batch fermentations. The reversibility of the acquired tolerance of B. longum, but not L. diacetylactis, to antibiotics was shown during successive free-Cell batch Cultures. Conclusions: Free Cells produced from continuous Immobilized-Cell Culture exhibited altered physiology and increased tolerance to various chemical and physico-chemical stresses. Significance and Impact of the Study: Continuous Culture with Immobilized Cells could be used to produce probiotic and lactic acid bacteria with enhanced technological and probiotic characteristics.
Y Doleyres - One of the best experts on this subject based on the ideXlab platform.
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continuous production of mixed lactic starters containing probiotics using Immobilized Cell technology
Biotechnology Progress, 2008Co-Authors: Y Doleyres, I Fliss, Christophe LacroixAbstract:The production of a mixed lactic Culture containing Lactococcus lactis subsp. lactis biovar. diacetylactis MD and Bifidobacterium longum ATCC 15707 was studied during a 17-day continuous Immobilized-Cell Culture at different temperatures between 32 and 37 °C. The two-stage fermentation system was composed of a first reactor (R1) containing Cells of the two strains separately Immobilized in κ-carrageenan/locust bean gum gel beads and a second reactor (R2) operated with free Cells released from the first reactor. The system allowed continuous production of a concentrated mixed Culture with a strain ratio whose composition depended on temperature and fermentation time. A stable mixed Culture (with a 22:1 ratio of L.diacetylactis and B. longum) was produced at 35 °C in the effluent of R2, whereas the mixed Culture was rapidly unbalanced in favor of B.longum at a higher temperature (37 °C) or L. diacetylactis at a lower temperature (32 °C). Strain redistribution in beads originally immobilizing pure Cultures of L. diacetylactis or B. longum was observed. At the end of Culture, the strain ratio (7:1 L. diacetylactis/B.longum) in bulk bead samples was similar to that of individual beads. The determination of the spatial distribution of the two strains in gel beads by immunofluorescence and confocal laser-scanning microscopy showed that bead cross-contamination was limited to a 100 μm peripheral layer. Data from this study validate a previous model for population dynamics and Cell release in gel beads during mixed Immobilized-Cell Cultures.
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increased stress tolerance of bifidobacterium longum and lactococcus lactis produced during continuous mixed strain Immobilized Cell fermentation
Journal of Applied Microbiology, 2004Co-Authors: Y Doleyres, I Fliss, Christophe LacroixAbstract:Y. DOLEYRES, I. FLISS AND C. LACROIX. 2004. Aims: The effect of immobilization and long-term continuous Culture was studied on probiotic and technological characteristics of lactic acid and probiotic bacteria. Methods and Results: A continuous Culture in a two-stage system was carried out for 17 days at different temperatures ranging from 32 to 37� C, with a first reactor containing Bifidobacterium longum ATCC 15707 and Lactococcus lactis subsp. lactis biovar. diacetylactis MD Immobilized separately in gel beads, and a second reactor operated with free Cells released from the first reactor. The tolerance of free Cells from both strains produced in the effluent medium of both reactors to hydrogen peroxide, simulated gastric and intestinal juices, antibiotics and nisin, and freeze-drying markedly increased with Culture time and was generally higher after 6 days than that of stationary-phase Cells produced during free-Cell batch fermentations. The reversibility of the acquired tolerance of B. longum, but not L. diacetylactis, to antibiotics was shown during successive free-Cell batch Cultures. Conclusions: Free Cells produced from continuous Immobilized-Cell Culture exhibited altered physiology and increased tolerance to various chemical and physico-chemical stresses. Significance and Impact of the Study: Continuous Culture with Immobilized Cells could be used to produce probiotic and lactic acid bacteria with enhanced technological and probiotic characteristics.
Thunyarat Pongtharangkul - One of the best experts on this subject based on the ideXlab platform.
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Nisin Production by Immobilized Microbial Cell Culture during Batch and Fed-Batch Fermentations with Various pH Profiles
Agricultural Engineering International: The CIGR Journal, 2008Co-Authors: Todd Jay Miserendino, Ali Demirci, Thunyarat PongtharangkulAbstract:In this study, nisin production has been enhanced by using batch and fed-batch fermentation with calcium-alginate Immobilized Cell Culture. Due to the inhibitory effects of original phosphate rich growth medium on the immobilizing beads, an altered complex growth medium for nisin production was used. Various pH profiles were evaluated for both batch and fed-batch fermentations. For batch fermentations, a 2.1 fold higher nisin activity was obtained by allowing the pH to drop freely after 4 hrs of fermentation at constant pH. A periodic pH profile exhibited a detrimental effect on nisin production during batch fermentations. For fed-batch fermentations, a 2.9 fold higher nisin activity was obtained by allowing the pH to remain at pH of 6.8. Approximately the same maximum concentration, 3300 IU/ml, of nisin was observed when the best pH profile for batch and fed batch experiments were compared. The results also showed that Immobilized Cell Culture can be used in order to improve nisin fermentation for both batch and fed-batch fermentation.
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Nisin Production by Immobilized Cell Culture during Batch and Fed-Batch Fermentations with Various pH Profiles
2006 Portland Oregon July 9-12 2006, 2006Co-Authors: Todd Jay Miserendino, Ali Demirci, Thunyarat PongtharangkulAbstract:In this study, nisin production has been enhanced by using batch and fed-batch fermentation with calcium-alginate Immobilized Cell Culture. Due to the detrimental effects of original phosphate rich growth medium on the immobilizing beads, an altered complex growth medium for nisin production was used. Various pH profiles were evaluated for both batch and fed-batch fermentations. For batch fermentations, a 2.1 fold higher nisin activity was obtained by allowing the pH to drop freely after 4 hrs of fermentation at constant pH. A step-wise pH profile exhibited a detrimental effect on nisin production during batch fermentations. For fed-batch fermentations, a 2.9 fold higher nisin activity was obtained by allowing the pH to remain at a constant pH of 6.8. The results clearly showed that Immobilized Cell Culture can be used in order to improve nisin fermentation for both batch and fed-batch fermentation.
Abdeltif Amrane - One of the best experts on this subject based on the ideXlab platform.
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Unstructured model for free and Immobilized Cell Culture without pH control of Bifidobacterium animalis subsp. lactis Bb 12 - Inhibitory effect of the undissociated organic acids.
Biochemical Engineering Journal, 2011Co-Authors: Hasan Jalili, Béatrice Balannec, Hadi Razavi, Abdeltif AmraneAbstract:A model was developed to describe growth and organic acids production of Bifidobacterium animalis growing without pH control in free and Immobilized Cell Culture. The Verlhust model was considered for growth, and to account for the inhibition observed at acidic pH, the Luedeking-Piret production model was modified by introducing an additional term involving the undissociated form of the organic acids, acetic and lactic acids, the main inhibitory species. To describe the relationship between pH and both the dissociated and the undissociated forms of organic acids, the Henderson-Hasselbach equation was considered. The model was found to satisfactory describe experimental growth and production data recorded during free and Immobilized Cell Cultures. The part of each acid produced can be deduced from the calculated production data, since a constant lactic to acetic acid mass ratio was found, 1.29 and 1.66 during free and Immobilized Cell Cultures. Owing to the acidic pH values recorded, 4.43 at lowest, higher amounts of undissociated acetic acid were produced, leading to a higher inhibitory effect of this acid if compared to lactic acid.
I Fliss - One of the best experts on this subject based on the ideXlab platform.
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continuous production of mixed lactic starters containing probiotics using Immobilized Cell technology
Biotechnology Progress, 2008Co-Authors: Y Doleyres, I Fliss, Christophe LacroixAbstract:The production of a mixed lactic Culture containing Lactococcus lactis subsp. lactis biovar. diacetylactis MD and Bifidobacterium longum ATCC 15707 was studied during a 17-day continuous Immobilized-Cell Culture at different temperatures between 32 and 37 °C. The two-stage fermentation system was composed of a first reactor (R1) containing Cells of the two strains separately Immobilized in κ-carrageenan/locust bean gum gel beads and a second reactor (R2) operated with free Cells released from the first reactor. The system allowed continuous production of a concentrated mixed Culture with a strain ratio whose composition depended on temperature and fermentation time. A stable mixed Culture (with a 22:1 ratio of L.diacetylactis and B. longum) was produced at 35 °C in the effluent of R2, whereas the mixed Culture was rapidly unbalanced in favor of B.longum at a higher temperature (37 °C) or L. diacetylactis at a lower temperature (32 °C). Strain redistribution in beads originally immobilizing pure Cultures of L. diacetylactis or B. longum was observed. At the end of Culture, the strain ratio (7:1 L. diacetylactis/B.longum) in bulk bead samples was similar to that of individual beads. The determination of the spatial distribution of the two strains in gel beads by immunofluorescence and confocal laser-scanning microscopy showed that bead cross-contamination was limited to a 100 μm peripheral layer. Data from this study validate a previous model for population dynamics and Cell release in gel beads during mixed Immobilized-Cell Cultures.
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increased stress tolerance of bifidobacterium longum and lactococcus lactis produced during continuous mixed strain Immobilized Cell fermentation
Journal of Applied Microbiology, 2004Co-Authors: Y Doleyres, I Fliss, Christophe LacroixAbstract:Y. DOLEYRES, I. FLISS AND C. LACROIX. 2004. Aims: The effect of immobilization and long-term continuous Culture was studied on probiotic and technological characteristics of lactic acid and probiotic bacteria. Methods and Results: A continuous Culture in a two-stage system was carried out for 17 days at different temperatures ranging from 32 to 37� C, with a first reactor containing Bifidobacterium longum ATCC 15707 and Lactococcus lactis subsp. lactis biovar. diacetylactis MD Immobilized separately in gel beads, and a second reactor operated with free Cells released from the first reactor. The tolerance of free Cells from both strains produced in the effluent medium of both reactors to hydrogen peroxide, simulated gastric and intestinal juices, antibiotics and nisin, and freeze-drying markedly increased with Culture time and was generally higher after 6 days than that of stationary-phase Cells produced during free-Cell batch fermentations. The reversibility of the acquired tolerance of B. longum, but not L. diacetylactis, to antibiotics was shown during successive free-Cell batch Cultures. Conclusions: Free Cells produced from continuous Immobilized-Cell Culture exhibited altered physiology and increased tolerance to various chemical and physico-chemical stresses. Significance and Impact of the Study: Continuous Culture with Immobilized Cells could be used to produce probiotic and lactic acid bacteria with enhanced technological and probiotic characteristics.
