The Experts below are selected from a list of 51210 Experts worldwide ranked by ideXlab platform
Kim Dam-johansen - One of the best experts on this subject based on the ideXlab platform.
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Reactor design for minimizing Product Inhibition during enzymatic lignocellulose hydrolysis: II. Quantification of Inhibition and suitability of membrane reactors.
2010Co-Authors: Pavle Andric, Peter Arendt Jensen, Anne S Meyer, Kim Dam-johansenAbstract:Abstract Product Inhibition of cellulolytic enzymes affects the efficiency of the biocatalytic conversion of lignocellulosic biomass to ethanol and other valuable Products. New strategies that focus on reactor designs encompassing Product removal, notably glucose removal, during enzymatic cellulose conversion are required for alleviation of glucose Product Inhibition. Supported by numerous calculations this review assesses the quantitative aspects of glucose Product Inhibition on enzyme-catalyzed cellulose degradation rates. The significance of glucose Product Inhibition on dimensioning of different ideal reactor types, i.e. batch, continuous stirred, and plug-flow, is illustrated quantitatively by modeling different extents of cellulose conversion at different reaction conditions. The main operational challenges of membrane reactors for lignocellulose conversion are highlighted. Key membrane reactor features, including system set-up, dilution rate, glucose output profile, and the problem of cellobiose are examined to illustrate the quantitative significance of the glucose Product Inhibition and the total glucose concentration on the cellulolytic conversion rate. Comprehensive overviews of the available literature data for glucose removal by membranes and for cellulose enzyme stability in membrane reactors are given. The treatise clearly shows that membrane reactors allowing continuous, complete, glucose removal during enzymatic cellulose hydrolysis, can provide for both higher cellulose hydrolysis rates and higher enzyme usage efficiency (kg Product /kg enzyme ). Current membrane reactor designs are however not feasible for large scale operations. The report emphasizes that the industrial realization of cellulosic ethanol requires more focus on the operational feasibility within the different hydrolysis reactor designs, notably for membrane reactors, to achieve efficient enzyme-catalyzed cellulose degradation.
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Reactor design for minimizing Product Inhibition during enzymatic lignocellulose hydrolysis: I. Significance and mechanism of cellobiose and glucose Inhibition on cellulolytic enzymes.
2010Co-Authors: Pavle Andric, Peter Arendt Jensen, Anne S Meyer, Kim Dam-johansenAbstract:Achievement of efficient enzymatic degradation of cellulose to glucose is one of the main prerequisites and one of the main challenges in the biological conversion of lignocellulosic biomass to liquid fuels and other valuable Products. The specific inhibitory interferences by cellobiose and glucose on enzyme-catalyzed cellulose hydrolysis reactions impose significant limitations on the efficiency of lignocellulose conversion — especially at high-biomass dry matter conditions. To provide the base for selecting the optimal reactor conditions, this paper reviews the reaction kinetics, mechanisms, and significance of this Product Inhibition, notably the cellobiose and glucose Inhibition, on enzymatic cellulose hydrolysis. Particular emphasis is put on the distinct complexity of cellulose as a substrate, the multi-enzymatic nature of the cellulolytic degradation, and the particular features of cellulase Inhibition mechanisms and kinetics. The data show that new strategies that place the bioreactor design at the center stage are required to alleviate the Product Inhibition and in turn to enhance the efficiency of enzymatic cellulose hydrolysis. Accomplishment of the enzymatic hydrolysis at medium substrate concentration in separate hydrolysis reactors that allow continuous glucose removal is proposed to be the way forward for obtaining feasible enzymatic degradation in lignocellulose processing.
Mario Moises Alvarez - One of the best experts on this subject based on the ideXlab platform.
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Production of probiotic biomass lactobacillus casei in goat milk whey comparison of batch continuous and fed batch cultures
2010Co-Authors: E J Aguirreezkauriatza, Jose M Aguilaryanez, Alicia Ramirezmedrano, Mario Moises AlvarezAbstract:Abstract This contribution examines the technical feasibility of producing high added value probiotic biomass from deproteinized and non-supplemented milk whey. The kinetics of growth of Lactobacillus casei in deproteinized goat milk whey was analyzed. Experiments in batch, continuous and fed-batch conditions were conducted in a 3 L fully instrumented bioreactor. Final substrate and biomass concentrations, yields and Productivities are reported for different culture strategies. A kinetic analysis was conducted to characterize biomass Production, Product Inhibition effects, and substrate consumption rates. Due to the strong Product Inhibition, fed-batch cultures at high biomass concentration rendered higher Productivity (0.45 g L−1 h−1) than batch and continuous cultures (0.11 g L−1 h−1), complete lactose conversions (
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Production of probiotic biomass lactobacillus casei in goat milk whey comparison of batch continuous and fed batch cultures
2010Co-Authors: E J Aguirreezkauriatza, Jose M Aguilaryanez, Alicia Ramirezmedrano, Mario Moises AlvarezAbstract:Abstract This contribution examines the technical feasibility of producing high added value probiotic biomass from deproteinized and non-supplemented milk whey. The kinetics of growth of Lactobacillus casei in deproteinized goat milk whey was analyzed. Experiments in batch, continuous and fed-batch conditions were conducted in a 3 L fully instrumented bioreactor. Final substrate and biomass concentrations, yields and Productivities are reported for different culture strategies. A kinetic analysis was conducted to characterize biomass Production, Product Inhibition effects, and substrate consumption rates. Due to the strong Product Inhibition, fed-batch cultures at high biomass concentration rendered higher Productivity (0.45 g L −1 h −1 ) than batch and continuous cultures (0.11 g L −1 h −1 ), complete lactose conversions ( 10 cell/g of freeze-dried Product). Based on our result, high-cell density fed-batch strategies are recommended for commercial Production of probiotic L. casei biomass.
Colin Webb - One of the best experts on this subject based on the ideXlab platform.
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Substrate and Product Inhibition kinetics in succinic acid Production by Actinobacillus succinogenes
2008Co-Authors: Sze Ki Carol Lin, Apostolis A. Koutinas, Ruohang Wang, Colin WebbAbstract:Abstract The Inhibition of substrate and Products on the growth of Actinobacillus succinogenes in fermentation using glucose as the major carbon source was studied. A. succinogenes tolerated up to 143 g/L glucose and cell growth was completely inhibited with glucose concentration over 158 g/L. Significant decrease in succinic acid yield and prolonged lag phase were observed with glucose concentration above 100 g/L. Among the end-Products investigated, formate was found to have the most inhibitory effect on succinic acid fermentation. The critical concentrations of acetate, ethanol, formate, pyruvate and succinate were 46, 42, 16, 74, 104 g/L, respectively. A growth kinetic model considering both substrate and Product Inhibition is proposed, which adequately simulates batch fermentation kinetics using both semi-defined and wheat-derived media. The model accurately describes the inhibitory kinetics caused by both externally added chemicals and the same chemicals produced during fermentation. This paper provides key insights into the improvement of succinic acid Production and the modelling of Inhibition kinetics.
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determination of apparent kinetic parameters for competitive Product Inhibition in packed bed immobilized enzyme reactors
2003Co-Authors: Ahmet R Ozdural, Deniz Tanyolac, Ismail Hakki Boyaci, Mehmet Mutlu, Colin WebbAbstract:Abstract In this study, a simple and effective technique for characterizing Michaelis–Menten type kinetics with competitive Product Inhibition in packed-bed re-circulated immobilized enzyme reactors is presented, where the use of nonlinear regression techniques for multi-parameter estimation are not required. In order to demonstrate the new technique introduced in this work, enzymatic conversion of lactose in a recycling packed-bed reactor is envisaged where β-galactosidase (lactase, EC 3.2.1.23) enzyme is immobilized on a weak base ion exchanger resin (Duolite A 568). For the experimental conditions used in this research, the total competitive Inhibition by Product (galactose) model is sufficient to represent the lactose hydrolysis kinetics in a packed-bed reactor.
Pavle Andric - One of the best experts on this subject based on the ideXlab platform.
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Reactor design for minimizing Product Inhibition during enzymatic lignocellulose hydrolysis: II. Quantification of Inhibition and suitability of membrane reactors.
2010Co-Authors: Pavle Andric, Peter Arendt Jensen, Anne S Meyer, Kim Dam-johansenAbstract:Abstract Product Inhibition of cellulolytic enzymes affects the efficiency of the biocatalytic conversion of lignocellulosic biomass to ethanol and other valuable Products. New strategies that focus on reactor designs encompassing Product removal, notably glucose removal, during enzymatic cellulose conversion are required for alleviation of glucose Product Inhibition. Supported by numerous calculations this review assesses the quantitative aspects of glucose Product Inhibition on enzyme-catalyzed cellulose degradation rates. The significance of glucose Product Inhibition on dimensioning of different ideal reactor types, i.e. batch, continuous stirred, and plug-flow, is illustrated quantitatively by modeling different extents of cellulose conversion at different reaction conditions. The main operational challenges of membrane reactors for lignocellulose conversion are highlighted. Key membrane reactor features, including system set-up, dilution rate, glucose output profile, and the problem of cellobiose are examined to illustrate the quantitative significance of the glucose Product Inhibition and the total glucose concentration on the cellulolytic conversion rate. Comprehensive overviews of the available literature data for glucose removal by membranes and for cellulose enzyme stability in membrane reactors are given. The treatise clearly shows that membrane reactors allowing continuous, complete, glucose removal during enzymatic cellulose hydrolysis, can provide for both higher cellulose hydrolysis rates and higher enzyme usage efficiency (kg Product /kg enzyme ). Current membrane reactor designs are however not feasible for large scale operations. The report emphasizes that the industrial realization of cellulosic ethanol requires more focus on the operational feasibility within the different hydrolysis reactor designs, notably for membrane reactors, to achieve efficient enzyme-catalyzed cellulose degradation.
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Reactor design for minimizing Product Inhibition during enzymatic lignocellulose hydrolysis: I. Significance and mechanism of cellobiose and glucose Inhibition on cellulolytic enzymes.
2010Co-Authors: Pavle Andric, Peter Arendt Jensen, Anne S Meyer, Kim Dam-johansenAbstract:Achievement of efficient enzymatic degradation of cellulose to glucose is one of the main prerequisites and one of the main challenges in the biological conversion of lignocellulosic biomass to liquid fuels and other valuable Products. The specific inhibitory interferences by cellobiose and glucose on enzyme-catalyzed cellulose hydrolysis reactions impose significant limitations on the efficiency of lignocellulose conversion — especially at high-biomass dry matter conditions. To provide the base for selecting the optimal reactor conditions, this paper reviews the reaction kinetics, mechanisms, and significance of this Product Inhibition, notably the cellobiose and glucose Inhibition, on enzymatic cellulose hydrolysis. Particular emphasis is put on the distinct complexity of cellulose as a substrate, the multi-enzymatic nature of the cellulolytic degradation, and the particular features of cellulase Inhibition mechanisms and kinetics. The data show that new strategies that place the bioreactor design at the center stage are required to alleviate the Product Inhibition and in turn to enhance the efficiency of enzymatic cellulose hydrolysis. Accomplishment of the enzymatic hydrolysis at medium substrate concentration in separate hydrolysis reactors that allow continuous glucose removal is proposed to be the way forward for obtaining feasible enzymatic degradation in lignocellulose processing.
E J Aguirreezkauriatza - One of the best experts on this subject based on the ideXlab platform.
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Production of probiotic biomass lactobacillus casei in goat milk whey comparison of batch continuous and fed batch cultures
2010Co-Authors: E J Aguirreezkauriatza, Jose M Aguilaryanez, Alicia Ramirezmedrano, Mario Moises AlvarezAbstract:Abstract This contribution examines the technical feasibility of producing high added value probiotic biomass from deproteinized and non-supplemented milk whey. The kinetics of growth of Lactobacillus casei in deproteinized goat milk whey was analyzed. Experiments in batch, continuous and fed-batch conditions were conducted in a 3 L fully instrumented bioreactor. Final substrate and biomass concentrations, yields and Productivities are reported for different culture strategies. A kinetic analysis was conducted to characterize biomass Production, Product Inhibition effects, and substrate consumption rates. Due to the strong Product Inhibition, fed-batch cultures at high biomass concentration rendered higher Productivity (0.45 g L−1 h−1) than batch and continuous cultures (0.11 g L−1 h−1), complete lactose conversions (
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Production of probiotic biomass lactobacillus casei in goat milk whey comparison of batch continuous and fed batch cultures
2010Co-Authors: E J Aguirreezkauriatza, Jose M Aguilaryanez, Alicia Ramirezmedrano, Mario Moises AlvarezAbstract:Abstract This contribution examines the technical feasibility of producing high added value probiotic biomass from deproteinized and non-supplemented milk whey. The kinetics of growth of Lactobacillus casei in deproteinized goat milk whey was analyzed. Experiments in batch, continuous and fed-batch conditions were conducted in a 3 L fully instrumented bioreactor. Final substrate and biomass concentrations, yields and Productivities are reported for different culture strategies. A kinetic analysis was conducted to characterize biomass Production, Product Inhibition effects, and substrate consumption rates. Due to the strong Product Inhibition, fed-batch cultures at high biomass concentration rendered higher Productivity (0.45 g L −1 h −1 ) than batch and continuous cultures (0.11 g L −1 h −1 ), complete lactose conversions ( 10 cell/g of freeze-dried Product). Based on our result, high-cell density fed-batch strategies are recommended for commercial Production of probiotic L. casei biomass.
