The Experts below are selected from a list of 37980 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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Cumulative effect of Yeast Extract and fructooligosaccharide supplementation on composition and metabolic activity of elderly colonic microbiota in vitro
Journal of Functional Foods, 2019Co-Authors: Eun-hee Doo, Clarissa Schwab, Christophe Chassard, Christophe LacroixAbstract:Concurrent with a decline in general health, elderly gut microbiota is characterized by reduced stability compared to adults, and is impacted by living condition and diet. Dietary supplementation was suggested to stabilize and promote elderly gut microbiota. We used two PolyFermS models to investigate the impact of fructooligo-saccharides (FOS), nucleosides (NS), and Yeast Extract (YE) supplementation on elderly colonic microbiota in vitro. NS, YE and FOS tested separately and combined at different addition levels increased the abundance of butyrate producers, lactobacilli and bifidobacteria. FOS and YE cumulatively increased butyrate levels, while propionate productions were decreased. Gene expression analysis indicated that FOS enhanced abundance of transcripts related to 'Di-and Oligosaccharides' and 'Fermentation' while treatments with FOS and YE alone and in combination altered the transcriptional profile of 'Amino Acids and Derivatives'. Our findings suggest that YE rich in nucleotides, amino acids, vitamins and minerals, enhance the butyrogenic effect of FOS.
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continuous lactic acid production in whey permeate Yeast Extract medium with immobilized lactobacillus helveticus in a two stage process model and experiments
Enzyme and Microbial Technology, 2006Co-Authors: Adolf Willem Schepers, Jules Thibault, Christophe LacroixAbstract:Abstract The effects of different culture parameters and operating strategies were tested on lactic acid production from whey permeate/Yeast Extract medium by immobilized Lactobacillus helveticus in a continuous two-stage process. High lactic acid productivities of 19–22 g l −1 h −1 and low residual sugar was achieved with an overall dilution rate of 0.5 h −1 and 10 g l −1 Yeast Extract. Lowering the Yeast Extract concentration from 10 to 1 g l −1 resulted in a gradual loss of activity with time in both reactors, leading to an overall lactic acid productivity of 10.5 g l −1 h −1 with 24 g l −1 residual sugar after 47 h. Inversion of the first and second reactor in the two-stage process led to an important drop in productivity which was only partly restored in the next 3 days of culture. Lactic acid and residual sugar concentrations in both reactors were predicted by a mathematical model, which combined mass transfer equations with a free-cell kinetic model of Lb. helveticus and did not use any fitting factor. Predicted concentrations were close to measured values during the first 18–24 h batch or continuous culture and, in general, during pseudo-steady-state continuous cultures in both reactors after this initial colonization period. However, transitions to a new pseudo-steady state, after changes in dilution rate and/or Yeast Extract concentration, were much slower in the experiment than those predicted by the model. Biomass and pH-gradients within gel beads, measured with fluorescent dyes and microelectrode, respectively, were only qualitatively predicted by the model. Our data suggest that an accurate description of immobilized cell activities cannot be done with kinetic models for free cells, especially for long-culture times, due to a change in the physiology of immobilized cells.
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lactobacillus helveticus growth and lactic acid production during ph controlled batch cultures in whey permeate Yeast Extract medium part i multiple factor kinetic analysis
Enzyme and Microbial Technology, 2002Co-Authors: Adolf Willem Schepers, Jules Thibault, Christophe LacroixAbstract:Abstract Twenty pH-controlled batch cultures with Lactobacillus helveticus were carried out in whey permeate-Yeast Extract medium according to a composite design with three factors: pH setpoint, and Yeast Extract and initial whey permeate concentrations. Growth and production parameters were estimated from experimental data with the Richards and Luedeking and Piret models, respectively, and analyzed statistically with response surfaces. The maximum specific growth rate, μ max , depended primarily on pH, with an optimum of 0.7 h −1 near pH 5.5. Whey permeate concentration had no direct effect on maximum specific growth rate, but showed a strong interaction with pH. Yeast Extract addition had a strong positive effect on maximum specific growth rate. During nitrogen-limited batch cultures X max depended on Yeast Extract concentration and pH, as well as on interactions of these variables with whey permeate concentration. The growth-associated lactic acid production parameter a was constant at 4.5 g lactic acid (g biomass) −1 , while the nongrowth-associated production parameter b, estimated during growth and early stationary phase, was a linear function of pH. This study allowed for the first detailed multifactor kinetic analysis of Lb. helveticus growth and lactic acid production, with a limited number of experiments, and demonstrated the importance of interactions among tested culture conditions.
Peter Morin Nissom - One of the best experts on this subject based on the ideXlab platform.
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low cost cultivation of sporosarcina pasteurii strain in food grade Yeast Extract medium for microbially induced carbonate precipitation micp application
Biocatalysis and agricultural biotechnology, 2019Co-Authors: Armstrong Ighodalo Omoregie, Lock Hei Ngu, Dominic Ek Leong Ong, Peter Morin NissomAbstract:Sporosarcina pasteurii is a well-known ureolytic microbial species that proficiently induces the deposition of calcium carbonate through microbially induced carbonate precipitation (MICP) process for various biotechnological and engineering purposes. In view to resolving the concern on high-cost bacterial cultivation due to the conventional use of laboratory-grade growth medium for MICP studies, an inexpensive food-grade Yeast medium was investigated in this current study for its feasibility to serve as a suitable alternative media for bacterial growth, urease activity and calcium carbonate precipitation. The effect of different media concentration and initial pH medium on biomass production and urease activity were determined. The performance of this low-cost media was also compared with eight laboratory-grade media (nutrient broth, Yeast Extract, tryptic soy broth, luria broth, fluid thioglycollate medium, cooked meat medium, lactose broth and marine broth). Results in this current study showed cultivation in low-cost media at 15 g L−1 (w/v) and initial pH 8.5 of the food-grade Yeast media both constituted the highest biomass concentration and urease activity when supplemented with urea (4%, w/v). Comparison of the food-grade media with laboratory-grade media indicated that bacterial cultivation cost was significantly reduced to 99.80%. After the biomineralization test, X-ray diffraction (XRD) analysis was used to confirm the elemental composition of CaCO3 and polymorphs which were identified as calcite and vaterite. These findings suggest the food-grade Yeast Extract can serve as a potential candidate for bacterial cultivation in MICP application from the perspective of cost reduction.
Marise Aparecida Rodrigues Pollonio - One of the best experts on this subject based on the ideXlab platform.
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adding lysine and Yeast Extract improves sensory properties of low sodium salted meat
Meat Science, 2020Co-Authors: Vitor Andre Silva Vidal, Jaqueline B Santana, Camila De Souza Paglarini, Maria Aparecida Azevedo Pereira Da Silva, Monica Q Freitas, Erick A Esmerino, Adriano G Cruz, Marise Aparecida Rodrigues PollonioAbstract:The partial reduction of Sodium Chloride (NaCl) and the use of lysine, Yeast Extract and substitute salts Potassium Chloride (KCl) and Calcium Chloride (CaCl2) in the characteristics of salted meat was investigated. Proximate composition, physicochemical properties (pH, water activity, lipid oxidation), instrumental analysis (color, shear force), microbiological analysis (total counts, lactic acid bacteria counts, thermally tolerant coliforms, and total coliforms) and sensory evaluation (120 consumers) were performed. The partial replacement of NaCl by KCl and CaCl2 significantly reduced the sodium content of salted meat treatments, while lysine and Yeast Extract minimized the negative sensory effects due to the addition of KCl and CaCl2. The addition of lysine and Yeast Extract increased the sensory acceptance and decreased rancid aroma, salty taste, and aftertaste of salted meat made with a blend of NaCl + KCl + CaCl2, with no differences in the physiochemical quality parameters. Moreover, the treatments made with the blend NaCl + KCl exhibited characteristics similar to traditional salted meat formulations.
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The effect of Yeast Extract addition on quality of fermented sausages at low NaCl content.
Meat Science, 2010Co-Authors: Paulo Cezar Bastianello Campagnol, Bibiana Alves Dos Santos, Roger Wagner, Nelcindo Nascimento Terra, Marise Aparecida Rodrigues PollonioAbstract:Abstract Fermented sausages with 25% or 50% of their NaCl replaced by KCl and supplemented with 1% or 2% concentrations of Yeast Extract were produced. The sausage production process was monitored with physical, chemical and microbiological analyses. After production, the sausage samples were submitted to a consumer study and their volatile compounds were Extracted by solid-phase microExtraction and analyzed by GC–MS. The replacement of NaCl by KCl did not significantly influence the physical, chemical or microbiological characteristics. The sensory quality of the fermented sausages with a 50% replacement was poor compared with the full-salt control samples. The use of Yeast Extract at a 2% concentration increased volatile compounds that arose from amino acids and carbohydrate catabolism. These compounds contributed to the suppression of the sensory-quality defects caused by the KCl introduction, thus enabling the production of safe fermented sausages that have acceptable sensory qualities with half as much sodium content.
Adolf Willem Schepers - One of the best experts on this subject based on the ideXlab platform.
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continuous lactic acid production in whey permeate Yeast Extract medium with immobilized lactobacillus helveticus in a two stage process model and experiments
Enzyme and Microbial Technology, 2006Co-Authors: Adolf Willem Schepers, Jules Thibault, Christophe LacroixAbstract:Abstract The effects of different culture parameters and operating strategies were tested on lactic acid production from whey permeate/Yeast Extract medium by immobilized Lactobacillus helveticus in a continuous two-stage process. High lactic acid productivities of 19–22 g l −1 h −1 and low residual sugar was achieved with an overall dilution rate of 0.5 h −1 and 10 g l −1 Yeast Extract. Lowering the Yeast Extract concentration from 10 to 1 g l −1 resulted in a gradual loss of activity with time in both reactors, leading to an overall lactic acid productivity of 10.5 g l −1 h −1 with 24 g l −1 residual sugar after 47 h. Inversion of the first and second reactor in the two-stage process led to an important drop in productivity which was only partly restored in the next 3 days of culture. Lactic acid and residual sugar concentrations in both reactors were predicted by a mathematical model, which combined mass transfer equations with a free-cell kinetic model of Lb. helveticus and did not use any fitting factor. Predicted concentrations were close to measured values during the first 18–24 h batch or continuous culture and, in general, during pseudo-steady-state continuous cultures in both reactors after this initial colonization period. However, transitions to a new pseudo-steady state, after changes in dilution rate and/or Yeast Extract concentration, were much slower in the experiment than those predicted by the model. Biomass and pH-gradients within gel beads, measured with fluorescent dyes and microelectrode, respectively, were only qualitatively predicted by the model. Our data suggest that an accurate description of immobilized cell activities cannot be done with kinetic models for free cells, especially for long-culture times, due to a change in the physiology of immobilized cells.
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lactobacillus helveticus growth and lactic acid production during ph controlled batch cultures in whey permeate Yeast Extract medium part i multiple factor kinetic analysis
Enzyme and Microbial Technology, 2002Co-Authors: Adolf Willem Schepers, Jules Thibault, Christophe LacroixAbstract:Abstract Twenty pH-controlled batch cultures with Lactobacillus helveticus were carried out in whey permeate-Yeast Extract medium according to a composite design with three factors: pH setpoint, and Yeast Extract and initial whey permeate concentrations. Growth and production parameters were estimated from experimental data with the Richards and Luedeking and Piret models, respectively, and analyzed statistically with response surfaces. The maximum specific growth rate, μ max , depended primarily on pH, with an optimum of 0.7 h −1 near pH 5.5. Whey permeate concentration had no direct effect on maximum specific growth rate, but showed a strong interaction with pH. Yeast Extract addition had a strong positive effect on maximum specific growth rate. During nitrogen-limited batch cultures X max depended on Yeast Extract concentration and pH, as well as on interactions of these variables with whey permeate concentration. The growth-associated lactic acid production parameter a was constant at 4.5 g lactic acid (g biomass) −1 , while the nongrowth-associated production parameter b, estimated during growth and early stationary phase, was a linear function of pH. This study allowed for the first detailed multifactor kinetic analysis of Lb. helveticus growth and lactic acid production, with a limited number of experiments, and demonstrated the importance of interactions among tested culture conditions.
Armstrong Ighodalo Omoregie - One of the best experts on this subject based on the ideXlab platform.
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low cost cultivation of sporosarcina pasteurii strain in food grade Yeast Extract medium for microbially induced carbonate precipitation micp application
Biocatalysis and agricultural biotechnology, 2019Co-Authors: Armstrong Ighodalo Omoregie, Lock Hei Ngu, Dominic Ek Leong Ong, Peter Morin NissomAbstract:Sporosarcina pasteurii is a well-known ureolytic microbial species that proficiently induces the deposition of calcium carbonate through microbially induced carbonate precipitation (MICP) process for various biotechnological and engineering purposes. In view to resolving the concern on high-cost bacterial cultivation due to the conventional use of laboratory-grade growth medium for MICP studies, an inexpensive food-grade Yeast medium was investigated in this current study for its feasibility to serve as a suitable alternative media for bacterial growth, urease activity and calcium carbonate precipitation. The effect of different media concentration and initial pH medium on biomass production and urease activity were determined. The performance of this low-cost media was also compared with eight laboratory-grade media (nutrient broth, Yeast Extract, tryptic soy broth, luria broth, fluid thioglycollate medium, cooked meat medium, lactose broth and marine broth). Results in this current study showed cultivation in low-cost media at 15 g L−1 (w/v) and initial pH 8.5 of the food-grade Yeast media both constituted the highest biomass concentration and urease activity when supplemented with urea (4%, w/v). Comparison of the food-grade media with laboratory-grade media indicated that bacterial cultivation cost was significantly reduced to 99.80%. After the biomineralization test, X-ray diffraction (XRD) analysis was used to confirm the elemental composition of CaCO3 and polymorphs which were identified as calcite and vaterite. These findings suggest the food-grade Yeast Extract can serve as a potential candidate for bacterial cultivation in MICP application from the perspective of cost reduction.