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Batch Reaction (batch + reaction)
Selected AbstractsIntegrated synthesis and extraction of short-chain fatty acid esters by supercritical carbon dioxideAICHE JOURNAL, Issue 4 2010Marta Lubary Abstract We developed an efficient, integrated reaction-extraction process for the production of short-chain fatty acid ethyl esters (FAEE) from milk fat, using carbon dioxide as the only processing solvent. FAEE were synthesized using a short-chain fatty acid selective lipase. The expansion of the liquid mixture of reactants by dense carbon dioxide enhanced the apparent lipase selectivity. In situ extraction of FAEE by a continuous flow of supercritical carbon dioxide proved to increase the lipase production rate. When the integrated process was operated with alternated periods of synthesis and product removal, the overall selectivity for short-chain FAEE increased as well, as a result of the combination of the selectivities of lipase and extraction solvent. A two-fold increase of the lipase productivity was achieved at these conditions, compared to a single batch reaction. The developed process enables the synthesis and isolation of high-value fatty acid derivatives from a natural source such as milk fat. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Cell-Free Protein Synthesis System Prepared from Insect Cells by Freeze-ThawingBIOTECHNOLOGY PROGRESS, Issue 6 2006Toru Ezure We established a novel cell-free protein synthesis system derived from Trichoplusia ni (HighFive) insect cells by a simple extraction method. Luciferase and ,-galactosidase were synthesized in this system with active forms. We analyzed and optimized (1) the preparation method of the insect cell extract, (2) the concentration of the reaction components, and (3) the 5,-untranslated region (5,-UTR) of mRNA. The extract was prepared by freeze-thawing insect cells suspended in the extraction buffer. This preparation method was a simple and superior method compared with the conventional method using a Dounce homogenizer. Furthermore, protein synthesis efficiency was improved by the addition of 20% (v/v) glycerol to the extraction buffer. Concentrations of the reaction components were optimized to increase protein synthesis efficiency. Moreover, mRNAs containing 5,-UTRs derived from baculovirus polyhedrin genes showed high protein synthesis activity. Especially, the leader composition of the Ectropis obliqua nucleopolyhedrovirus polyhedrin gene showed the highest enhancement activity among the six 5,-UTRs tested. As a result, in a batch reaction approximately 71 ,g of luciferase was synthesized per milliliter of reaction volume at 25 °C for 6 h. Moreover, this method for the establishment of a cell-free system was applied also to Spodoptera frugiperda 21 (Sf21) insect cells. After optimizing the concentrations of the reaction components and the 5,-UTR of mRNA, approximately 45 ,g/mL of luciferase was synthesized in an Sf21 cell-free system at 25 °C for 3 h. These productivities were sufficient to perform gene expression analyses. Thus, these cell-free systems may be a useful tool for simple synthesis in post-genomic studies as a novel protein production method. [source] Characteristics of Immobilized Lipase on Hydrophobic Superparamagnetic Microspheres To Catalyze EsterificationBIOTECHNOLOGY PROGRESS, Issue 2 2004Zheng Guo A novel immobilized lipase (from Candida rugosa) on hydrophobic and superparamagnetic microspheres was prepared and used as a biocatalyst to catalyze esterification reactions in diverse solvents and reaction systems. The results showed that the immobilized lipase had over 2-fold higher activities in higher log P value solvents. An exponential increase of lipase activity against log P of two miscible solvent mixtures was observed for the first time. Both free and immobilized lipase achieved its maximum activity at the range of water activity ( aw) 0.5,0.8 or higher. At aw 0.6, the immobilized lipase exhibited markedly higher activities in heptane and a solvent-free system than did the native lipase. In multicompetitive reactions, the alcohol specificity of the lipase showed a strong chain-length dependency, and the immobilized enzyme exhibited more preference for a longer-chain alcohol, which is different from previous reports. The immobilized lipase showed higher specificities for butyric acid and the medium-chain-length fatty acids (C8,C12). Then, the immobilized lipase was extended to solvent-free synthesis of glycerides from glycerol and fatty acids. Recovered by magnetic separation, the immobilized lipase exhibited good reusability in repeated batch reaction, indicating its promising feature for biotechnology application. [source] A Feasible Enzymatic Process for d -Tagatose Production by an Immobilized Thermostable l -Arabinose Isomerase in a Packed-Bed BioreactorBIOTECHNOLOGY PROGRESS, Issue 2 2003Hye-Jung Kim To develop a feasible enzymatic process for d -tagatose production, a thermostable l -arabinose isomerase, Gali152, was immobilized in alginate, and the galactose isomerization reaction conditions were optimized. The pH and temperature for the maximal galactose isomerization reaction were pH 8.0 and 65 °C in the immobilized enzyme system and pH 7.5 and 60 °C in the free enzyme system. The presence of manganese ion enhanced galactose isomerization to tagatose in both the free and immobilized enzyme systems. The immobilized enzyme was more stable than the free enzyme at the same pH and temperature. Under stable conditions of pH 8.0 and 60 °C, the immobilized enzyme produced 58 g/L of tagatose from 100 g/L galactose in 90 h by batch reaction, whereas the free enzyme produced 37 g/L tagatose due to its lower stability. A packed-bed bioreactor with immobilized Gali152 in alginate beads produced 50 g/L tagatose from 100 g/L galactose in 168 h, with a productivity of 13.3 (g of tagatose)/(L-reactor·h) in continuous mode. The bioreactor produced 230 g/L tagatose from 500 g/L galactose in continuous recycling mode, with a productivity of 9.6 g/(L·h) and a conversion yield of 46%. [source] Prolonging Cell-Free Protein Synthesis by Selective Reagent AdditionsBIOTECHNOLOGY PROGRESS, Issue 3 2000Dong-Myung Kim Factors causing the early cessation of protein synthesis have been studied in a cell-free system from Escherichia coli. We discovered that phosphoenol pyruvate (PEP), the secondary energy source for ATP regeneration, and several amino acids are rapidly degraded during the cell-free protein synthesis reaction. The degradation of such compounds takes place even in the absence of protein synthesis. This degradation severely reduces the capacity for protein synthesis. The lost potency was completely recovered when the reaction mixture was supplied with additional PEP and amino acids. Of the 20 amino acids, only arginine, cysteine, and tryptophan were required to restore system activity. Through repeated additions of PEP, arginine, cysteine,and tryptophan, the duration of protein synthesis was greatly extended. In this fed-batch reaction, after a 2 h incubation, the level of cell-free synthesized chloramphenicol acetyl transferase (CAT) reached 350 ,g/mL, which is 3.5 times the yield of the batch reaction. Addition of fresh magnesium further extended the protein synthesis. As a result, through coordinated additions of PEP, arginine, cysteine, tryptophan, and magnesium, the final concentration of cell-free synthesized CAT increased more than 4-fold compared to a batch reaction. SDS-PAGE analysis of such a fed-batch reaction produced an obvious band of CAT upon Coomassie Blue staining. [source] Rapid estimation of chemical kinetics by implicit calibration.JOURNAL OF CHEMOMETRICS, Issue 2 2003Abstract This study continues the development of a method, implicit calibration, for estimating kinetic parameters from on-line measurements of batch reactions. The basic idea of implicit calibration is to combine non-linear parameter estimation with the calibration of measured spectra with concentrations calculated by an assumed kinetic model. A new example is studied, an esterification reaction with a rather complicated kinetic mechanism, where activities, instead of concentrations, and NIR spectra are used as measurements. The emphasis in the study is on estimating the uncertainty of the kinetic parameters. Two approaches, linearization and bootstrap, are applied. In the case studied, the two approaches give closely similar estimates of the uncertainty. As well, a new way is introduced to control the rigidity of the implicit calibration, based on minimizing the lack of fit of the model. It is also shown that ,mixed implicit calibration', i.e. implicit calibration combined with a few off-line calibrated concentrations, greatly enhances the identifiability of the kinetic model. Copyright © 2003 John Wiley & Sons, Ltd. [source] Matrix Representation of Polymer Chain Size Distributions, 3 , Case Studies for Linear Polymerization Mechanisms at Transient ConditionsMACROMOLECULAR THEORY AND SIMULATIONS, Issue 4-5 2008Heloísa L. Sanches Abstract The mass balance equations used to describe different polymerization systems are represented and analyzed with the help of a general matrix framework previously developed. Some of its properties were presented in previous works and are illustrated here in three examples. The first example regards the dynamics of a copolymerization reactor. It is shown that terminal and penultimate models may predict qualitatively different responses in batch reactions. The second example also regards the dynamics of copolymerization reactions. It is shown how manipulation of initial conditions and monomer feed rates can be used to keep copolymer composition constant throughout the batch. The third example concerns the existence of oscillating chain size distributions when there are multiple monomer insertion steps. [source] Using non-invasive magnetic resonance imaging (MRI) to assess the reduction of Cr(VI) using a biofilm,palladium catalystBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010D.A. Beauregard Abstract Industrial waste streams may contain contaminants that are valuable like Pd(II) and/or toxic and mutagenic like Cr(VI). Using Serratia sp. biofilm the former was biomineralized to produce a supported nanocrystalline Pd(0) catalyst, and this biofilm,Pd heterogeneous catalyst was then used to reduce Cr(VI) to less dangerous Cr(III) at room temperature, with formate as the electron donor. Cr(VI)(aq) is non-paramagnetic while Cr(III)(aq) is paramagnetic, which enabled spatial mapping of Cr species concentrations within the reactor cell using non-invasive magnetic resonance (MR) imaging experiments. Spatial reactivity heterogeneities were thus examined. In batch reactions, these could be attributed primarily to heterogeneity of Pd(0) distribution and to the development of gas bubbles within the reactor. In continuous flow reactions, spatial reactivity heterogeneities resulted primarily from heterogeneity of Cr(VI) delivery. Biotechnol. Bioeng. 2010;107: 11,20. © 2010 Wiley Periodicals, Inc. [source] Mechanistic model for prediction of formate dehydrogenase kinetics under industrially relevant conditionsBIOTECHNOLOGY PROGRESS, Issue 1 2010T. Schmidt Abstract Formate dehydrogenase (FDH) from Candida boidinii is an important biocatalyst for the regeneration of the cofactor NADH in industrial enzyme-catalyzed reductions. The mathematical model that is currently applied to predict progress curves during (semi-)batch reactions has been derived from initial rate studies. Here, it is demonstrated that such extrapolation from initial reaction rates to performance during a complete batch leads to considerable prediction errors. This observation can be attributed to an invalid simplification during the development of the literature model. A novel mechanistic model that describes the course and performance of FDH-catalyzed NADH regeneration under industrially relevant process conditions is introduced and evaluated. Based on progress curve instead of initial reaction rate measurements, it was discriminated from a comprehensive set of mechanistic model candidates. For the prediction of reaction courses on long time horizons (>1 h), decomposition of NADH has to be considered. The model accurately describes the regeneration reaction under all conditions, even at high concentrations of the substrate formate and thus is clearly superior to the existing model. As a result, for the first time, course and performance of NADH regeneration in industrial enzyme-catalyzed reductions can be accurately predicted and used to optimize the cost efficiency of the respective processes. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Regioselective Enzymatic Diol Esterification in Batch and Fixed-Bed Adsorptive Reactors: Experiments and ModelingBIOTECHNOLOGY PROGRESS, Issue 4 2000Cristiano Migliorini The dynamic behavior of batch and fixed-bed adsorptive reactors is studied for the enzyme-catalyzed regioselective esterification of propionic acid and 2-ethyl-1,3-hexanediol in hexane. The reaction is equilibrium-limited with an apparent equilibrium constant of 0.6 ± 0.1 at 22 °C. Moreover, accumulation of water produced in the reaction onto the biocatalyst causes a decrease in the catalytic activity. As a result, improvements in both reaction rate and final conversion can be achieved by operating in an adsorptive-reactor mode. Control of water in the reactor is achieved with a catalytically inert ion-exchange resin in Na-form. The resin prevents an excessive accumulation of water on the biocatalyst and reduces equilibrium limitations. The thermodynamic activity of water is identified as a key parameter for the design of such reactors. A mathematical model capable of predicting the water activity as a function of the varying concentrations of reactants and products is thus developed and found to successfully predict the experimental behavior observed in laboratory reactors. Substantial improvements in performance predicted by the model are seen experimentally in batch reactions and during the transient operation of continuous-flow fixed-bed reactors combining adsorptive and catalytic functions. [source] | |||||||||||||