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  • Articles  (91)
  • kinetics  (91)
  • Process Engineering, Biotechnology, Nutrition Technology  (91)
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  • 1
    Electronic Resource
    Electronic Resource
    Static and Kinetic Studies on the Adsorption Behavior of Sulfadiazene (2000)
    Springer
    Adsorption 6 (2000), S. 349-357 
    Details
    ISSN: 1572-8757
    Keywords: sulfadiazene ; adsorption ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract To investigate the nature of interactive forces between sulfadiazene molecules and alumina surface the experiments were performed for the adsorption of sulfadiazene (SD) from its aqueous sulution onto the alumina surfaces at 25 ± 0.2°C and the influence of factors such as increasing concentration of SD (4.0–20.0 × 10−3 mol cm−3), the time required for adsorption equilibrium, pH (2.0–12.0) and temperature (5–45°C) of the adsorption medium, the presence of ions like Cl−, SO2− 4 and PO3− 4 (0.01–0.30 M) and organic solvents (5% v/v) were observed on the course of adsorption of SD. Various adsorption and kinetic parameters such as adsorption coefficient, the rate constants for adsorption and desorption were also evaluated. The results of the above cited studies facilitated to formulate the mechanisms of interaction between SD and alumina surfaces. From application view point the present work may be a potential tool for an effective chromatographic separation of sulfa drugs from industrial effluents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026517117239
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  • 2
    Electronic Resource
    Electronic Resource
    Why Does the Linear Driving Force Model for Adsorption Kinetics Work? (2000)
    Springer
    Adsorption 6 (2000), S. 137-147 
    Details
    ISSN: 1572-8757
    Keywords: adsorption ; kinetics ; linear driving force model ; process design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The Linear Driving Force (LDF) model for gas adsorption kinetics is frequently and successfully used for analysis of adsorption column dynamic data and for adsorptive process designs because it is simple, analytic, and physically consistent. Yet, there is a substantial difference in the characteristics of isothermal batch uptake curves on adsorbent particles by the LDF and the more rigorous Fickian Diffusion (FD) model. It is demonstrated by using simple model systems that the characteristics of the adsorption kinetics at the single pore or the adsorbent particle level are lost in (a) evaluating overall uptake on a heterogeneous porous solid, (b) calculating breakthrough curves from a packed adsorbent column, and (c) establishing the efficiency of separation by an adsorptive process due to repeated averaging of the base kinetic property. That is why the LDF model works in practice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008965317983
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  • 3
    Electronic Resource
    Electronic Resource
    A weighing method to identify the microbial growth phases in solid-state fermentation tests (2000)
    Springer
    World journal of microbiology and biotechnology 16 (2000), S. 601-605 
    Details
    ISSN: 1573-0972
    Keywords: Growth phases identification ; kinetics ; Rhizopus oryzae ; solid-state fermentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A general equation correlating the variation rate of the fermenting medium weight (dry matter) and the cell biomass growth rate in solid-state fermentation tests is proposed with the main purpose of identifying the microbial growth phases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008970720794
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  • 4
    Electronic Resource
    Electronic Resource
    Pure and Binary Gas Adsorption Equilibria and Kinetics of Methane and Nitrogen on 4A Zeolite by Isotope Exchange Technique (1999)
    Springer
    Adsorption 5 (1999), S. 145-158 
    Details
    ISSN: 1572-8757
    Keywords: kinetics ; isotope-exchange ; nitrogen ; adsorption ; methane ; zeolite ; equilibria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The Isotope Exchange Technique (IET) was used to simultaneously measure pure and binary gas adsorption equilibria and kinetics (self-diffusivities) of CH4 and N2 on pelletized 4A zeolite. The experiment was carried out isothermally without disturbing the adsorbed phase. CH4 was selectively adsorbed over N2 by the zeolite because of its higher polarizability. The multi-site Langmuir model described the pure gas and binary adsorption equilibria fairly well at three different temperatures. The selectivity of adsorption of CH4 over N2 increased with increasing pressure at constant gas phase composition and temperature. This curious behavior was caused by the differences in the sizes of the adsorbates. The diffusion of CH4 and N2 into the zeolite was an activated process and the Fickian diffusion model described the uptake of both pure gases and their mixtures. The self-diffusivity of N2 was an order of magnitude larger than that for CH4. The pure gas self-diffusivities for both components were constants over a large range of surface coverages (0 〈 θ 〈 0.5). The self-diffusivities of CH4 and N2 from their binary mixtures were not affected by the presence of each other, compared to their pure gas self-diffusivities at identical surface coverages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008917308002
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  • 5
    Electronic Resource
    Electronic Resource
    Sorption Equilibria and Kinetics of Hydrocarbons onto Activated Carbon Samples Having Different Micropore Size Distributions (1999)
    Springer
    Adsorption 5 (1999), S. 25-37 
    Details
    ISSN: 1572-8757
    Keywords: micropore size distribution ; activated carbon ; adsorption ; desorption ; equilibrium ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract This paper deals with the prediction of adsorption equilibrium and kinetics of hydrocarbons onto activated carbon samples having different micropore size distribution (MPSD). The microporous structure of activated carbon is characterised by the distribution of slit-shaped micropores, which is assumed to be the sole source of surface heterogeneity. The interaction between adsorbate molecule and pore walls is described by the Lennard-Jones potential theory. Different adsorbates have access to different pore size range of activated carbon due to the size exclusion, a phenomenon could have a significant influence on both multicomponent equilibria and kinetics. Activated carbons with three different MPSDs are studied with ethane and propane as the two model adsorbates. The Heterogeneous Macropore Surface Diffusion model (HMSD) is employed to simulate adsorption kinetics. The simulation results show that the MPSD is an important factor affecting both the multicomponent equilibria and kinetics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026481704926
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  • 6
    Electronic Resource
    Electronic Resource
    A theoretical equation describing the time evolution of the concentration of a selected range of substrate molecular weights in depolymerization processes mediated by single-attack mechanism endo -enzymes (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 387-393 
    Details
    ISSN: 0006-3592
    Keywords: depolymerization ; kinetics ; endo -enzymes ; theoretical equation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Monitoring the time evolution of the concentration of a selected range of molecular weights of substrate, referred to as “detectable” substrate, has been used to determine endo-enzymic activities in polysaccharide depolymerizing processes. In the methodologies based on the use of dye-labeled substrates, the “detectable” substrate extends from a given molecular weight threshold downward. On the contrary, in the fluorescent probe-flow injection analysis methodology, initially developed to determine (1 → 3)-(1 → 4)-β-d-glucanase activities, the “detectable” substrate extends from a given molecular weight threshold upward. Assuming that the time evolution of the molecular weight distribution of the substrate follows the most probable distribution (the enzymic attack is random and its mechanism is single attack), a theoretical equation describing the time evolution of the concentration of “detectable” substrate (from a given molecular weight threshold upward or downward) has been deduced. This equation, Wd = Wo · (1 + αt) · e-αt, where Wd is the concentration of “detectable” substrate, Wo is the initial concentration of the substrate, t is the depolymerization time, and α is a parameter correlated through a hyperbola with the initial concentrations of enzyme and substrate and the Michaelis-Menten constant, Km, has been tested against different (1 → 3)-(1 → 4)-β-d-glucan/(1 → 3)-(1 → 4)-β-d-glucanase systems using the fluorescent probe-flow injection analysis methodology and Calcofluor as the fluorescent probe. The most important predictions of the theoretical equation, which allow accurate determination of both endo-enzymic activities and kinetic constants, have been experimentally confirmed. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 387-393, 1998.
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  • 7
    Electronic Resource
    Electronic Resource
    Mixing and phase hold-ups variations due to gas production in anaerobic fluidized-bed digesters: Influence on reactor performance (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 60 (1998), S. 36-43 
    Details
    ISSN: 0006-3592
    Keywords: anaerobic fluidized bed ; hydrodynamics ; biogas production ; kinetics ; model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of mixing and phase hold-ups on gas-producing fluidized-bed reactors was investigated and compared with an ideal flow reactor performance (CSTR). The liquid flow in the anaerobic fluidized bed reactor could be described by the classical axially dispersed plug flow model according to measurements of residence time distribution. Gas effervescence in the fluidized bed was responsible for bed contraction and for important gas hold-up, which reduced the contact time between the liquid and the bioparticles. These results were used to support the modeling of large-scale fluidized-bed reactors. The biological kinetics were determined on a 180-L reactor treating wine distillery wastewater where the overall total organic carbon uptake velocity could be described by a Monod model. The outlet concentration and the concentration profile in the reactor appeared to be greatly influenced by hydrodynamic limitations. The biogas effervescence modifies the mixing characteristics and the phase hold-ups. Bed contraction and gas hold-up data are reported and correlated with liquid and gas velocities. It is shown that the reactor performance can be affected by 10% to 15%, depending on the mode of operation and recycle ratio used. At high organic loading rates, reactor performance is particularly sensitive to gas effervescence effects. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 36-43, 1998.
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  • 8
    Electronic Resource
    Electronic Resource
    A unified model describing the role of hydrogen in the growth of Desulfovibrio vulgaris under different environmental conditions (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 732-746 
    Details
    ISSN: 0006-3592
    Keywords: Desulfovibrio vulgaris ; hydrogen cycling ; kinetics ; thermodynamics ; modeling ; anaerobic ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A unified model for the growth of Desulfovibrio vulgaris under different environmental conditions is presented. The model assumes the existence of two electron transport mechanisms functioning simultaneously. One mechanism results in the evolution and consumption of hydrogen, as in the hydrogen-cycling model. The second mechanism assumes a direct transport of electrons from the donor to the acceptor, without the participation of H2. A combination of kinetic and thermodynamic conditions control the flow of electrons through each pathway. The model was calibrated using batch experiments with D. vulgaris grown on lactate, in the presence and absence of sulfate, and was verified using additional batch experiments under different conditions. The model captured the general trends of consumption of substrates and accumulation of products, including the transient accumulation and consumption of H2. Furthermore, the model estimated that 48% of the electrons transported from lactate to sulfate involved H2 production, indicating that hydrogen cycling is a fundamental process in D. vulgaris. The presence of simultaneous electron transport mechanisms might provide D. vulgaris with important ecological advantages, because it facilitates a rapid response to changes in environmental conditions. This model increases our ability to study the microbial ecology of anaerobic environments and the role of Desulfovibrio species in a variety of environments. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:732-746, 1998.
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  • 9
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    Electronic Resource
    Respirometric assay for biofilm kinetics estimation: Parameter identifiability and retrievability (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 35-45 
    Details
    ISSN: 0006-3592
    Keywords: biofilm ; attached growth ; respirometry ; parameter estimation ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Currently, no fast and accurate methods exist for measuring extant biokinetic parameters for biofilm systems. This article presents a new approach to measure extant biokinetic parameters of biofilms and examines the numerical feasibility of such a method. A completely mixed attached growth bioreactor is subjected to a pulse of substrate, and oxygen consumption is monitored by on-line measurement of dissolved oxygen concentration in the bulk liquid. The oxygen concentration profile is then fit with a mechanistic mathematical model for the biofilm to estimate biokinetic parameters. In this study a transient biofilm model is developed and solved to generate dissolved oxygen profiles in the bulk liquid. Sensitivity analysis of the model reveals that the dissolved oxygen profiles are sufficiently sensitive to the biokinetic parameters - the maximum specific growth rate coefficient (⁁μ) and the half-saturation coefficient (Ks) - to support parameter estimation if accurate estimates of other model parameters can be obtained. Monte Carlo simulations are conducted with the model to add typical measurement error to the generated dissolved oxygen profiles. Even with measurement error in the dissolved oxygen profile, a pair of biokinetic parameters is always retrievable. The geometric mean of the parameter estimates from the Monte Carlo simulations prove to be an accurate estimator for the true biokinetic values. Higher precision is obtained for ⁁μ estimates than for Ks estimates. In summary, this theoretical analysis reveals that an on-line respirometric assay holds promise for measuring extant biofilm kinetic parameters. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 35-45, 1998.
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  • 10
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    Biodegradation of 1,1,1-trichloroethane by a carbon tetrachloride-degrading denitrifying consortium (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 393-399 
    Details
    ISSN: 0006-3592
    Keywords: denitrification ; biodegradation ; kinetics ; 1,1,1-trichloroethane ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A denitrifying consortium capable of degrading carbon tetrachloride (CT) was shown to also degrade 1,1,1-trichloroethane (TCA). Fed-batch experiments demonstrated that the specific rate of TCA degradation by the consortium was comparable to the specific rate of CT degradation (approximately 0.01 L/gmol/min) and was independent of the limiting nutrient. Although previous work demonstrated that 4-50% of CT transformed by the consortium was converted to chloroform (CF), no reductive dechlorination products were detected during TCA degradation, regardless of the limiting nutrient. The lack of chlorinated TCA degradation products implies that the denitrifying consortium possesses an alternate pathway for the degradation of chlorinated solvents which does not involve reductive dechlorination. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:393-399, 1998.
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  • 11
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    Rapid biocatalytic polytransesterification: Reaction kinetics in an exothermic reaction (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 428-437 
    Details
    ISSN: 0006-3592
    Keywords: enzymes ; polyesters ; bulk polymerization ; calorimetry ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biocatalytic polytransesterification at high concentrations of monomers proceeds rapidly and is accompanied by an increase in the temperature of the reaction mixture due to liberation of heat of reaction during the initial phase. We have used principles of reaction calorimetry to monitor the kinetics of polymerization during this initial phase, thus relating the temperature to the extent of polymerization. Rate of polymerization increases with the concentration of monomers. This is also reflected by the increase in the temperature of the reaction mixture. Using time-temperature-conversion contours, a differential method of kinetic analysis was used to calculate the energy of activation (∼15.1 Kcal/mol). © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:428-437, 1998.
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  • 12
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    Applicability of competitive and noncompetitive kinetics to the reductive dechlorination of chlorinated ethenes (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 751-755 
    Details
    ISSN: 0006-3592
    Keywords: PCE ; chlorinated ethenes ; kinetics ; bioremediation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Reductive dechlorination of chlorinated ethenes has typically been modeled using standard Michaelis-Menten kinetic equations, implying that each dechlorination step is catalyzed by a unique biological factor. An alternative kinetic model is based on the assumption that all steps are mediated by a single factor. These two options are considered in the context of chlorinated ethene degradation by a previously characterized anaerobic culture. Competitive kinetics afford better chi-squared and visual fits of the data set tested. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 751-755, 1998
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  • 13
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    Determinants and rate laws of growth and death of hybridoma cells in continuous culture (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 642-654 
    Details
    ISSN: 0006-3592
    Keywords: animal cell culture ; growth ; cell death ; kinetics ; autoinhibitor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental data from six hybridoma cell lines grown under diverse experimental conditions in both normal continuous and perfusion cultures are analyzed with respect to the significance of nutrients and products in determining the growth and death rates of cells and with respect to their mathematical modeling. It is shown that neither nutrients (glucose and glutamine) nor the common products lactic acid, ammonia, and monoclonal antibody can be generally assumed to be the clear-limiting or inhibiting factors for most of the cultures. Correspondingly, none of the unstructured models existing in the literature can be generally applied to describe the experimental data obtained over a relatively wide range of cultivation conditions as considered in this work. Surprisingly, for all cultures the specific growth rate (μ) almost linearly correlates with the ratio of the viable cell concentration (NV) to the dilution (perfusion) rate (D). Similarly, the specific death rate (kd) is a function of the ratio of the total cell concentration (Nt) to the dilution (perfusion) rate. These results strongly suggest the formation of not yet identified critical factors or autoinhibitors that determine both the growth and death rates of hybridoma cells. Based on these observations, simple kinetic models are developed for μ and kd which describe the experimental data satisfactorily. Analysis of the experimental data with the kinetic models reveals that under the current cultivation conditions the formation rate of the autoinhibitor(s) or the sensitivity of cell growth and death to the autoinhibitor(s) is mainly affected by the medium composition. Irrespective of the cell lines, cells grown on serum-containing media have almost the same model parameters, which are distinctively different from those of cells grown on serum-free media. Furthermore, in contrast to the prevailing view, kd is shown to positively correlate with μ if the effects of cell concentration and dilution (perfusion) rate are considered. Several important implications of these findings are discussed for the optimization and control of animal cell culture. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 642-654, 1998
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  • 14
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    Equilibria and kinetics characterisation of two different structured nutshell-derived activated carbons (1997)
    Springer
    Adsorption 3 (1997), S. 267-275 
    Details
    ISSN: 1572-8757
    Keywords: characterisation ; equilibria ; kinetics ; micropore size distribution ; n-butane ; nutshell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Adsorption equilibria and dynamics ofn-butane on two activated carbon samples prepared from the physical activation of nutshell are studied in this paper. The micropore size distribution (MPSD) is considered as the main source of solid heterogeneity. Lennard-Jones' potential theory and Dubinin's theory (TVFM) are used in the equilibria data to derive the MPSD, which is well fitted by a Gamma distribution function. The adsorption energy distribution derived from the MPSD is very asymmetric for both the samples studied, and this energy distribution used in the HMSD/HMSMD kinetics models for the study of adsorption dynamics ofn-butane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01653629
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  • 15
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    On the kinetics of degradation of cellulose (1997)
    Springer
    Cellulose 4 (1997), S. 1-5 
    Details
    ISSN: 1572-882X
    Keywords: paper ; degradation ; ageing ; kinetics ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018408515574
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  • 16
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    Determination of carbon dioxide evolution rate using on-line gas analysis during dynamic biodegradation experiments (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 53 (1997), S. 243-252 
    Details
    ISSN: 0006-3592
    Keywords: carbon dioxide evolution rate ; mass transfer ; modeling ; biodegradation ; pH ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Respirometry is a precious tool for determining the activity of microbial populations. The measurement of oxygen uptake rate is commonly used but cannot be applied in anoxic or anaerobic conditions or for insoluble substrate. Carbon dioxide production can be measured accurately by gas balance techniques, especially with an on-line infrared analyzer. Unfortunately, in dynamic systems, and hence in the case of short-term batch experiments, chemical and physical transfer limitations for carbon dioxide can be sufficient to make the observed carbon dioxide evolution rate (OCER) deduced from direct gas analysis very different from the biological carbon dioxide evolution rate (CER).To take these transfer phenomena into account and calculate the real CER, a mathematical model based on mass balance equations is proposed. In this work, the chemical equilibrium involving carbon dioxide and the measured pH evolution of the liquid medium are considered. The mass transfer from the liquid to the gas phase is described, and the response time of the analysis system is evaluated.Global mass transfer coefficients (KLa) for carbon dioxide and oxygen are determined and compared to one another, improving the choice of hydrodynamic hypotheses. The equations presented are found to give good predictions of the disturbance of gaseous responses during pH changes.Finally, the mathematical model developed associated with a laboratory-scale reactor, is used successfully to determine the CER in nonstationary conditions, during batch experiments performed with microorganisms coming from an activated sludge system. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 243-252, 1997.
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  • 17
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    Identification of linearity in the biofilm process and its operational utility (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 53 (1997), S. 253-258 
    Details
    ISSN: 0006-3592
    Keywords: biofilm ; deep biofilm reactor (DBFR) ; kinetics ; linearity ; operational control ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Various reported field studies on the performance of biofilm reactors suggest that the linear control of the system is effective for maintaining the consistent treatment efficiency under changing environmental conditions. However, no theoretical basis is available in the literature to substantiate such a claim. In this article, inherent linearity of the biofilm process has been identified along with the conditions under which this linearity exists. Exploiting the linear state of the system, operational criteria for regulating the performance of the biofilm reactors are obtained. The utility and applicability of the developed criteria are numerically demonstrated. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 253-258, 1997.
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  • 18
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    Kinetics and modeling of GM-CSF production by recombinant yeast in a three-phase fluidized bed bioreactor (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 53 (1997), S. 470-477 
    Details
    ISSN: 0006-3592
    Keywords: fluidized bed bioreactor ; recombinant ; yeast ; kinetics ; modeling ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous production of a recombinant murine granulocyte-macrophage colony-stimulating factor (GM-CSF) by Saccharomyces cerevisiae strain XV2181 (a/a, Trp 1) containing plasmid pαADH2 and immobilized on porous glass beads in a fluidized bed bioreactor was studied. Kinetic models for plasmid stability, cell growth, and protein production in the three-phase fluidized bed bioreactor were developed and used to study the effects of solid loading or cell immobilization on plasmid stability and recombinant protein production. With increasing cell immobilization or solid loading in the bioreactor, plasmid stability and protein production improved significantly. The improvements could be attributed to the decreased θ value, which is the plasmid loss probability during cell division and is an indication of segregational instability of the recombinant cell, and the increased α value, which is the ratio of the specific growth rate of a plasmid-carrying cell to that of a plasmid-free cell and is indicative of competitive stability of the recombinant cell culture. θ decreased from 0.552 to 0.042 and α increased from 0.351 to 0.991 when solid loading in the bioreactor was increased from 5% (v/v) to 33%. The model simulation also showed that the specific growth rate of cells in the bioreactor was lower at higher solid loading. This indicated that there was significant mass transfer limitation, particularly for oxygen transfer, when the total cell density in the bioreactor was high at high solid loading. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 470-477, 1997.
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  • 19
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    Kinetics and equilibria of condensation reactions between monosaccharide pairs catalyzed by Aspergillus niger glucoamylase (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 56 (1997), S. 9-22 
    Details
    ISSN: 0006-3592
    Keywords: condensation reactions ; disaccharides ; equilibria ; glucoamylase ; kinetics ; monosaccharides ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Arabinose, fructose, galactose, myo-inositol, lyxose, mannose, ribose, and xylose were incubated individually and with glucose in the presence of Aspergillus niger glucoamylase at pH 4.5 and 45°C. Glucoamylase condenses galactose, glucose, and mannose individually into disaccharides. It also produces mixed disaccharides when each of the eight carbohydrates is incubated with glucose. Many products were identified by gas chromatography of the derivatized reaction mixtures followed by mass spectroscopy of the individual chromatographic peaks. Galacto-, gluco-, or mannopyranosyl rings appear to be present at the nonreducing ends of all the disaccharides produced. Molecules linked through primary hydroxyl groups have the highest equilibrium constants of all products formed, since these bonds are thermodynamically favored. However, glucoamylase is capable of forming bonds with many available hydroxyl groups, as previously demonstrated when it was incubated with glucose alone. Formation rates of different bonds linking different residues vary widely. These results demonstrate that glucoamylase has a wide selectivity toward residues it will condense into disaccharides and toward bonds it will form between them. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 9-22, 1997.
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  • 20
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    Effect of hypoxia duration on the oxygen-dependent production of a recombinant protein, β-galactosidase, by an animal cell line, F6D2, with a hypoxia-inducible enhancer (1997)
    Springer
    Cytotechnology 25 (1997), S. 71-77 
    Details
    ISSN: 1573-0778
    Keywords: hypoxia ; recombinant protein ; animal cells ; erythropoietin ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Expression of specific genes is a strategy of animal cells for adaptation to oxygen deficiency and the mechanism underlying the hypoxic activation of gene expression may be useful for efficient production of recombinant proteins by animal cells, because oxygen is a limiting factor in animal cell cultures. We prepared an animal cell line harboring the plasmid in which expression of a reporter gene, β-galactosidase, is controlled by an enhancer responsible for the hypoxic activation of gene transcription. The purpose of this paper is to understand this hypoxic production of recombinant proteins quantitatively by a mathematical model originally developed based on the following hypotheses; 1 lacZ (the reporter gene) is transcribed after HIF-1 protein complex is bound to the hypoxic enhancer, 2. β-galactosidase synthesis rate is limited at the transcription of lacZ, 3. HIF-1 is an inactive form under a normal oxygen concentration, 4. Oxygen works as a repressor in the synthesis of HIF-1 protein, 5. Both β-galactosidase and HIF-1 are decomposed according to the first order reaction. The effects of hypoxic duration as well as oxygen concentration on the β-galactosidase production were successfully predicated by the model.
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    URL: http://dx.doi.org/10.1023/A:1007911816292
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    Kinetics of U(VI) reduction by a dissimilatory Fe(III)-reducing bacterium under non-growth conditions (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 55 (1997), S. 490-496 
    Details
    ISSN: 0006-3592
    Keywords: uranium ; kinetics ; precipitation ; shewanella ; metal reduction ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dissimilatory metal-reducing microorganisms may be useful in processes designed for selective removal of uranium from aqueous streams. These bacteria can use U(VI) as an electron acceptor and thereby reduce soluble U(VI) to insoluble U(IV). While significant research has been devoted to demonstrating and describing the mechanism of dissimilatory metal reduction, the reaction kinetics necessary to apply this for remediation processes have not been adequately defined. In this study, pure culture Shewanella alga strain BrY reduced U(VI) under non-growth conditions in the presence of excess lactate as the electron donor. Initial U(VI) concentrations ranged from 13 to 1680 μM. A maximum specific U(VI) reduction rate of 2.37 μmole-U(VI)/(mg-biomass h) and Monod half-saturation coefficient of 132 μM-U(VI) were calculated from measured U(VI) reduction rates. U(VI) reduction activity was sustained at 60% of this rate for at least 80 h. The initial presence of oxygen at a concentration equal to atmospheric saturation at 22°C delays but does not prevent U(VI) reduction. The rate of U(VI) reduction by BrY is comparable or better than rates reported for other metal reducing species. BrY reduces U(VI) at a rate that is 30% of its Fe(III) reduction rate. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 490-496, 1997.
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    Kinetic characterization of mass transfer limited biodegradation of a low water soluble gas in batch experiments - Necessity for multiresponse fitting (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 55 (1997), S. 511-519 
    Details
    ISSN: 0006-3592
    Keywords: ethene ; kinetics ; biodegradation ; mass transfer ; multiresponse fitting ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method was developed to characterize the kinetics of biodegradation of low water soluble gaseous compounds in batch experiments. The degradation of ethene by resting Mycobacterium E3 cells was used as a model system. The batch degradation data were recorded as the progress curve (i.e., the time course of the ethene concentration in the headspace of the batch vessel). The recorded progress curves, however, suffered gas:liquid mass transfer limitation. A new multiresponse fitting method had to be developed to allow unequivocal identification of both the affinity coefficient, Kaff, and the gas:liquid mass transfer coefficient, Kla, in the batch vessel from the mass transfer limited data. Simulation showed that the Kaff estimate obtained is influenced by the dimensionless (volumetric basis) ethene gas:liquid partitioning coefficient (H). In the fitting procedure, Monod, Teissier, and Blackman biokinetics were evaluated for characterization of the ethene biodegradation process. The fits obtained reflected the superiority of the Blackman biokinetic function. Overall, it appears that resting Mycobacterium E3 cells metabolizing ethene at 24°C have, using Blackman biokinetics, a maximum specific degradation rate, vmax, of 10.2 nmol C2H4 mg-1 CDW min-1, and an affinity coefficient, Kaff.g, expressed in equilibrium gas concentration units, of 61.9 ppm, when H is assumed equal to 8.309. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 511-519, 1997.
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    Shift from growth to nutrient-limited maintenance kinetics during biofilter acclimation (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 56 (1997), S. 330-339 
    Details
    ISSN: 0006-3592
    Keywords: biofilter ; kinetics ; maintenance metabolism ; acclimation ; biomass ; nutrient limitation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: During long-term operation of a biofilter, the mandatory absence of net cell growth forces the cells into maintenance metabolism, which is of relatively low rate compared to substrate consumption during the active growth of the acclimation phase. A model based on this shift in metabolism can explain the postacclimation decrease in activity sometimes reported for biofilters. The cessation of growth can be caused by nutrient depletion in the bed. Postacclimation nutrient addition increases activity primarily by allowing a return to the high substrate consumption rate of active growth, and only secondarily helps raise bed activity because of the ultimately higher amount of biomass in the bed. Simulations incorporating the acclimation period and the role of maintenance metabolism predict about 4 logarithms of growth during acclimation of a hexane biofilter, which was confirmed experimentally. Changes in a biofilter's biomass during the acclimation phase can be estimated from substrate conversion data using two approximate methods. The first follows the cumulative amount of substrate converted and uses the estimated yield of cells from substrate during active growth to estimate the total biomass created. The second method follows a rate constant for conversion of substrate in the bed. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 330-339, 1997.
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    Frequency response analysis of a closed diffusion cell with two resonators (1996)
    Springer
    Adsorption 2 (1996), S. 265-277 
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    ISSN: 1572-8757
    Keywords: frequency response ; diffusion cell ; kinetics ; diffusion ; heat effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract This paper deals with frequency response (FR) analysis of a closed diffusion cell system with two resonators, that is both the LHS and RHS volumes are modulated. The analysis is made for a homogeneous particle described by a single effective diffusivity as well as a biporous pellet described by macropore and micropore diffusions. It is shown that if the perturbation of the volume of the reservoir #2 is lagged behind that of the reservoir #1 by 3π/2, the pressure response in reservoir #1 is significantly enhanced with larger amplitude as well as phase angle. When the perturbations of the two reservoirs are out of phase, the heat effect is reduced and can become insignificant when the two perturbations are completely out of phase (ψ = π). Under such a condition, the pressure difference between the two reservoirs could be doubled. In the case of biporous pellets, it is shown that the FR behaviours obtained for micropore diffusion control and macropore diffusion control are well distinguished. In the former case, the FR system reduces to a traditional batch adsorber one while in the latter case, the FR behaviour is the same as for a two resonator system with homogeneous particles. This difference can be used for the discrimination of micropore and macropore diffusion processes.
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    Prediction of paper permanence by accelerated aging I. Kinetic analysis of the aging process (1996)
    Springer
    Cellulose 3 (1996), S. 243-267 
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    ISSN: 1572-882X
    Keywords: aging tests ; cellulose degradation ; durability ; kinetics ; paper properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The validity of accelerated aging tests to predict and rank papers on their permanence has been under question, preventing the development of performance-based standards for permanent paper. We conducted a general kinetic analysis to investigate the aging process of paper. A general kinetic model is proposed to describe the depolymerization of cellulose. Experimentally it was shown that in the case of aging, cellulose degradation follows classic first-order kinetics as a special case of our general kinetic model. The Arrhenius equation was critically re-examined for the case of a multiple reaction system. It was shown analytically that the Arrhenius equation is still applicable when certain conditions are met. This was convincingly supported by experimental results. We also analysed the dependence of the degradation rate on the moisture content and hydrogen ion concentration. By conducting systematic experiments on these two factors, a general and quantitative relationship was established to explain the contribution of each factor and their interactions. Finally, based on this kinetic analysis, the effects of storage conditions on the life expectancy of paper were estimated.
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    Prediction of paper permanence by accelerated aging II. Comparison of the predictions with natural aging results (1996)
    Springer
    Cellulose 3 (1996), S. 269-279 
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    ISSN: 1572-882X
    Keywords: accelerated tests ; aging tests ; cellulose degradation ; durability ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Accelerated aging tests are credible and useful to predict paper permanence only if such tests can be shown to correlate with natural aging. In the first part of this study, a kinetic model was developed based on the accelerated aging results. In this report, we have shown that this kinetic model can indeed predict the natural aging results of lignin-free sheets with a statistical confidence. This is the first quantitative comparison of accelerated aging with natural aging.
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    Chlorine decay and bacterial inactivation kinetics in drinking water in the tropics (1996)
    Springer
    World journal of microbiology and biotechnology 12 (1996), S. 549-556 
    Details
    ISSN: 1573-0972
    Keywords: Bacteria inactivation ; chlorine decay ; combined chlorine ; drinking water ; free chlorine ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The decay of free chlorine (Cl2) and combined chlorine (mostly monochloramine: NH2Cl) and the inactivation of bacteria was examined in Dar es Salaam, Tanzania. Batch experiments, pilot-scale pipe experiments and full-scale pipe experiments were carried out to establish the kinetics for both decay and inactivation, and to compare the two disinfectants for use under tropical conditions. The decay of both disinfectants closely followed first order kinetics, with respect to the concentration of both disinfectant and disinfectant-consuming substances. Bacterial densities exhibited a kinetic pattern consisting of first order inactivation with respect to the density of the bacteria and the concentration of the disinfectant, and first order growth with respect to the bacterial density. The disinfection kinetic model takes the decaying concentration of the disinfectant into account. The decay rate constant for free chlorine was 114 lg-1h-1, while the decay rate constant for combined chlorine was 1.84 lg-1h-1 (1.6% of the decay rate for free chlorine). The average concentration of disinfectant consuming substances in the water phase was 2.6 mg Cl2/l for free chlorine and 5.6 mg NH2Cl/l for combined chlorine. The decay rate constant and the concentration of disinfectant consuming substances when water was pumped through pipes, depended on whether or not chlorination was continuous. Combined chlorine especially could clean the pipes of disinfectant consuming substances. The inactivation rate constant λ, was estimated at 3.06×104 lg-1h-1. Based on the inactivation rate constant, and a growth rate constant determined in a previous study, the critical concentration of free chlorine was found to be 0.08 mg Cl2/l. The critical concentration is a value below which growth rates dominate over inactivation.
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    A comparative study of the purity, enzyme activity, and inactivation by hydrogen peroxide of commercially available horseradish peroxidase isoenzymes A and C (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 50 (1996), S. 655-662 
    Details
    ISSN: 0006-3592
    Keywords: horseradish peroxidase ; peroxide ; kinetics ; inactivation ; suicide substrate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Horseradish peroxidase (HRP) is a commercially important enzyme that is available from a number of supply houses in a variety of grades of purity and isoenzymic combinations. The present article describes a comparative study made on nine HRP preparations. Six of these samples were predominantly composed of basic HRP, pl 8.5, and three of acidic HRP, pl 3.5. Two of the basic preparations were of lower purity than the others. The apparent molar catalytic activity of basic HRP with 0.5 mMABTS and 0.2 mM H2O2 was around 950 s-1 (about 770 s-1 for the less pure samples) and with a 5 mM guaiacol and 0.6 mM H2O2 was about 180 s-1 for all the samples. A similar value (approximately 1000 s-1) was observed for acidic HRP but only at higher concentrations of ABTS (20 mM). With 20 mM guaiacol the molar catalytic activity of the acid isoenzyme was 65 s-1. The apparent KM for ABTS of the acidic isoenzyme was 4 mM whereas for the basic isoenzyme it was 0.1 mM. All the enzymes were inactivated by H2O2 when it was supplied as the only substrate. Under these conditions the partition ratio (r = number of catalytic cycles given by the enzyme before its inactivation), apparent dissociation constant (Kl), and apparent rate constant of inactivation (kinact) were about twice as large for the acidic samples (1350, 2.6 mM, 9 · 10-3 s-1) as for the basic (650, 1.3 mM, 5 · 10-3 s-1). The apparent catalytic constant (kcat) was 3-4 times larger, and the efficiency of catalysis (kcat/Kl) was double for the acidic isoenzyme, but the efficiency of inactivation (kinact/Kl) was similar. The data obtained provide useful information for those using HRP isoenzymes for biotechnological applications (e.g., biosensors, bioreactors, or assays). © 1996 John Wiley & Sons, Inc.
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    Kinetics of chromate reduction during naphthalene degradation in a mixed culture (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 52 (1996), S. 357-363 
    Details
    ISSN: 0006-3592
    Keywords: chromium ; chromate ; naphthalene ; reduction ; kinetics ; model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mixed culture of Bacillus sp. K1 and Sphingomonas paucimobilis EPA 505 was exposed to chromate and naphthalene. Batch experiments showed that chromate was reduced and naphthalene was degraded by the mixed culture. Chromate reduction occurred initially at a high rate followed by a decrease in rate until chromate reduction ceased. Chromate reduction decreased in the mixed culture when a lower ratio of S. paucimobilis EPA 505 to Bacillus sp. K1 was utilized. A kinetic model incoporating a term for the cell density ratio is proposed to describe chromate reduction in the mixed culture under both chromate limited and electron donor limited conditions. The validity of the model, and its parameter values, was verified by experimental data generated under a variety of initial population compositions and a broad range of chromate concentrations. The consistent result of experimental data with model predictions implies that the model is useful for evaluating the interactions and the use of mixed culture for chromate removal. © 1996 John Wiley & Sons, Inc.
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    A structured model of dual-limitation kinetics (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 683-689 
    Details
    ISSN: 0006-3592
    Keywords: dual limitation ; cofactor responses ; kinetics ; multiplicative model ; structured model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A structured model of substrate-utilization kinetics that encompasses dual-limitation conditions, caused by simultaneously low concentrations of the electron donor and the electron acceptor, is developed by incorporating the internal cofactor responses into the kinetic variables. The structured model is based on an assumption that the maximum specific electron-donor-oxidation rate (qmd) is not a constant, but is linearly controlled by the intracellular chemical potentials, log(NAD/NADH) and log(ATP/ADP · Pi). Determination of the kinetic parameters for the dual-limitation model, using experimental data from the companion article, verifies that qmd varies and demonstrates that the NAD/NADH ratio affects qmd in a positive direction; thus, an increase of the ratio increases the rate of electron-donor utilization. Because the internal NAD/NADH ratio rises with an increase in Sar the specific electron-donor-utilization rate is accelerated by high Sa. Since the ratio also increases as the specific electron-donor-utilization rate falls, the specific rate is intrinsically accelerated by the cofactor response when it becomes low due to a depletion of electron donor. Because the cofactor responses upon changes of the external substrate concentrations are systematic, the dual-limitation model can be expressed as a function of only external concentrations of electron donor and electron acceptor, which results in a multiplicative (double-Monod) form. Thus, dual limitation by both substrates reduces the overall reaction rate below the rate expected from single limitation by only one, the most severely limiting, substrate. © 1996 John Wiley & Sons, Inc.
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    Hybridomas in a bioreactor cascade: modeling and determination of growth and death kinetics (1996)
    Springer
    Cytotechnology 21 (1996), S. 263-277 
    Details
    ISSN: 1573-0778
    Keywords: hybridomas ; serum-free medium ; monoclonal antibodies ; reactor series ; kinetics ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Hybridomas were cultured under steady-state conditions in a series of two continuous stirred-tank reactors (CSTRs), using a serum-free medium. The substrate not completely converted in the first CSTR, was transported with the cells to the second one and very low growth rates, high death rates, and lysis of viable cells were observed in this second CSTR. These conditions are hardly accessible in a single vessel, because such experiments would be extremely time-consuming and unstable due to a low viability. In contrast to what is often observed in literature, kinetic parameters could thus be derived without the neccessity for extrapolation to lower growth rates. Good agreement with literature averages for other hybridomas was found. Furthermore, showing that the reactor series is a valuable research tool for kinetic studies under extreme conditions, the possibility to observe cell death under stable and defined steady-state conditions offers interesting opportunities to investigate apoptosis and necrosis. Additionally, a model was developed that describes hybridoma growth and monoclonal antibody production in the bioreactor cascade on the basis of glutamine metabolism. Good agreement between the model and the experiments was found.
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    A rapid method for determining kinetic parameters of enzymes exhibiting nonlinear thermal inactivation bahavior (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 106-110 
    Details
    ISSN: 0006-3592
    Keywords: inactivation ; thermal inactivation ; enzymes ; alcohol dehydrogenase ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A rapid method is developed to analyze the kinetics of thermal inactivation of enzymes that exhibit a nonlinear biphasic log(activity)-time relationship. Thermal destruction experiments on alcohol dehydrogenase from baker's yeast demonstrate the applicability of the method. The method is based on physical considerations (as opposed to mathematical curve fitting/regression methods) and also serves as a quick check of results obtained using nonlinear regression. It is superior to fitting nonlinear enzyme inactivation data by first-order kinetics or taking the initial and final slopes of the inactivation data. In fact, the method is of general validity and can be applied to any decay process that can be represented by a sum of exponentials. © 1996 John Wiley & Sons, Inc.
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    Sensitivity of PSA process performance to input variables (1995)
    Springer
    Adsorption 1 (1995), S. 133-151 
    Details
    ISSN: 1572-8757
    Keywords: PSA process ; sensitivity ; equilibria ; kinetics ; heats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Mathematical models for pressure swing adsorption (PSA) processes essentially require the simultaneous solutions of mass, heat and momentum balance equations for each step of the process using appropriate boundary conditions for the steps. The key model input variables needed for estimating the separation performance of the process are the multicomponent adsorption equilibria, kinetics and heats of adsorption for the system of interest. A very detailed model of an adiabatic Skarstrom PSA cycle for production of high purity methane from a ethylene-methane bulk mixture is developed to study the sensitivity of the process performance to the input variables. The adsorption equilibria are described by the heterogeneous Toth model which accounts for variations of isosteric heats of adsorption of the components with adsorbate loading. A linear driving force model is used to describe the kinetics. The study shows that small errors in the heats of adsorption of the components can severely alter the overall performance of the process (methane recovery and productivity). The adsorptive mass transfer coefficients of the components also must be known fairly accurately in order to obtain precise separation performance.
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    Kinetics of nitrate inhibition of carbon tetrachloride transformation by a denitrifying consortia (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 279-284 
    Details
    ISSN: 0006-3592
    Keywords: carbon tetrachloride ; nitrate inhibition ; biodegradation ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of nitrate inhibition of carbon tetrachloride (CT) transformation were examined using a denitrifying consortium. Comparison of data from fed-batch experiments to the model reported by Hooker et al. indicate that the inhibition constant ranges between 3.2 and 21 mg/L, with an average of 8.8 mg/L. This range is much lower than the previously reported value of 169 mg/L. Simulations using the corrected parameter accurately reflect this new data and the data reported by Hooker et al. In contrast, the earlier reported coefficient value does not reflect the data reported in this work. © 1995 John Wiley & Sons, Inc.
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    A structured metabolic model for anaerobic and aerobic stoichiometry and kinetics of the biological phosphorus removal process (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 277-287 
    Details
    ISSN: 0006-3592
    Keywords: phosphorus removal ; biological ; kinetics ; metabolic model ; polyphosphate ; PHB ; glycogen ; batch reactor, sequenced ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A structured metabolic model is developed that describes the stoichiometry and kinetics of the biological P removal process. In this approach all relevant metabolic reactions underlying the metabolism, considering also components like adenosine triphosphate (ATP) and nic-otinamide-adenine dinucleotide (NADH2) are describedbased on biochemical pathways. As a consequence of the relations between the stoichiometry of the metabolic reactions and the reaction rates of components, the required number of kinetic relations to describe the process is reduced. The model describes the dynamics of the storage compounds which are considered separately from the active biomass. The model was validated in experiments at a constant sludge retention time of 8 days, over the anaerobic and aerobic phases in which the external oncentrations as well as the internal fractions of the relevant components involved in the P-removal process were monitored. These measurements include dissolved acetate, phosphate, and ammonium; oxygen consumption; poly-β-hydroxybutyrate (PHB); glycogen; and active biomass. The model satisfactorily describes the dynamic behavior of all components during the anaerobicand aerobic phases.© 1995 John Wiley & Sons, Inc
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    The Use of RP-HPLC for measuring activation and cleavage of rFVIIa during purification (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 501-505 
    Details
    ISSN: 0006-3592
    Keywords: RP-HPLC ; rFVIIa ; activation ; cleavage ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A reverse phase HPLC (RP-HPLC) method for analysis of recombinant factor VIIa (rFVIIa) has been developed. The method discriminates between different forms of recombinant FVII (rFVII). To obtain separation of these closely related molecules the method has been optimized with respect to gradient profile and temperature. The method has been used for optimization of purification processes and for kinetic studies. EVidence for autolytic cleavage was obtained. © 1995 John Wiley & Sons, Inc.
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    The Monod equation and mass transfer (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 91-94 
    Details
    ISSN: 0006-3592
    Keywords: mass transfer ; Monod equation ; growth rate ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An alternative interpretation of the growth rate-substrate concentration dependence is presented. This is based on the assumption that the main factors affecting growth rate are transfer of substrate from the medium and the maximum growth velocity, which is that observed when no substrate limitations occur. This approach allows the approximate prediction of one of the two kinetic constants required, and may be of great use, especially for continuous cultures. It is the first attempt to provide a phenomenological explanation for the large variations observed in the values of the Monod constant, Ks, reported in the literature. © 1995 John Wiley & Sons, Inc.
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    Kinetics of phase separation for polyethylene glycol-phosphate two-phase systems (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 246-256 
    Details
    ISSN: 0006-3592
    Keywords: polyethylene glycol ; phosphate ; phase separation ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Phase separation times for polyethylene glycol (PEG)-4000-phosphate aqueous two-phase systems were studied, for small scale (5-g) and large scale (1300-g) systems, as a -function of the stability ratio. Profiles of dispersion height for both large and small scale systems were represented as a fraction of the initial height and were found to be independent of the geometrical dimensions of the separator. Furthermore, by plotting time as a fraction of the initial height the total time of separation can be calculated for a given height of system at a particular stability ratio. This generalization is important for the design of large scale aqueous two-phase separators. Phase separation times were also found to be dependent on which of the phases is continuous. A characteristic change in phase separation time was also observed at the phase inversion point (i.e., where the dispersed phase changes to a continuous phase and vice versa) and this point tends toward higher volume ratios as the tie-line length (TLL) is increased. Furthermore, the phase inversion point at each TLL corresponds to a fixed phosphate concentration. © 1995 John Wiley & Sons, Inc.
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    Catalytic behavior of Pseudomonas cepacia lipase in w/o microemulsions (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 33-41 
    Details
    ISSN: 0006-3592
    Keywords: lipase ; reverse micelles ; surfactants ; esterification ; glycerides ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The activity of purified Pseudomonas cepacia lipase has been investigated in esterification reactions of various aliphatic alcohols with natural fatty acids. The reactions were carried out in microemulsions formed in isooctane by bis-(2-ethylhexyl)sulfosuccinate sodium salt (AOT). Kinetic studies showed that the reaction follows a ping-pong bi-bi mechanism with inhibition by both substrates. The apparent kinetic parameters of the reaction were found to be Km octanol = 310 mM, Km lauric acid = 78 mM, and Vmax = 250 μmol min-1 mg-1. The same system was used for the synthesis of mono- and diglycerides from glycerol and lauric acid, which was successful at very low wo values. The catalytic behavior of P. cepacia lipase was also studied in esterification reactions performed in a nonionic microemulsion system formulated by tetraethyleneglycoldodecylether (C12E4). The optimum activity was found at about wo = 8. The apparent values of Vmax app and Km app for octanol were calculated and found to be 100 μmol min-1 mg-1 and 76 mM, respectively. © 1995 John Wiley & Sons, Inc.
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    Effect of yeast extract on growth kinetics during aerobic biodegradation of chlorobenzoic acids (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 227-233 
    Details
    ISSN: 0006-3592
    Keywords: chiorobenzoic acids ; yeast extract ; kinetics ; growth kinetics ; dechlorination ; biodegradation ; Pseudomonas ; Alcaligenes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Monod or Andrews kinetic parameters describing the growth of Pseudomonas sp. CPE2 strain on 2,5-dich!orobenzoic acid and 2-chlorobenzoic acid, and Al-caligenes sp. CPE3 strain on 3,4-dichlorobenzoic acid, 4-chlorobenzoic acid, and 3-chlorobenzoic acid were determined from batch and continuous growth experiments conducted in the presence or absence of yeast extract (50 mg/L). Strain CPE2 displayed inhibitory growth kinetics in the absence of yeast extract and a noninhibitory kinetics in the presence of yeast extract. Similar results were obtained for CPE3. The presence of yeast extract also resulted in a significant increase in the affinity of the strains for the chlorobenzoic acids they degraded. © 1995 John Wiley & Sons, Inc.
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    Mass transfer and temperature effects on substrate utilization in brewery granules (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 465-475 
    Details
    ISSN: 0006-3592
    Keywords: anaerobic granules ; mass transfer ; temperature effect ; kinetics ; acetate ; propionate ; ethanol ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Liquid film and diffusional resistances of brewery granules during acetate, propionate, and ethanol utilization were investigated. Substrate utilization rate increased with decreased granule size. Effectiveness factors for acetate, propionate, and ethanol were calculated by comparing the maximum rates of substrate utilization of whole granules (1.8 to 3.0 mm) and fine flocs (20 to 75 μm) derived by disrupting whole granules. For acetate, propionate, and ethanol, maximum specific substrate utilization rates (km′ g/g VS · d) for the flocs, were 5.11, 6.25, and 5.49, respectively, and half-velocity coefficients (Kg′ mM) were 0.45, 0.40, and 3.37, respectively. Calculated effectiveness factors were 0.32, 0.41, and 0.75 for acetate, propionate, and ethanol, respectively. The effect of temperature on substrate utilization was examined at 26°C, 31°C, and 37°C using acetate as sole carbon source. Utilization rates increased with temperature. Flocs were most sensitive to temperature, and whole granules were least affected. The behavior of flocs was well described by the Van't Hoff-Arrhenius equation. Effectiveness factors for acetate utilization by the granules were 0.36, 0.35, and 0.32 at 26°C, 31°C, and 37°C, respectively, indicating little effect of temperature. Based on these results, we conclude that both liquid film and diffusional resistances influenced the rate of substrate utilization in a UASB reactor with granular sludge. Temperature effects were much less important than diffusional limitations within the granules. © 1995 John Wiley & Sons, Inc.
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    Kinetics and mass transfer for lactic acid recovered with anion exchange method in fermentation solution (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 1-7 
    Details
    ISSN: 0006-3592
    Keywords: anion exchange ; lactic acid ; kinetics ; mass transfer ; exchange isotherm ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An anion exchange method for lactic acid recovered from lactic acid-glucose solution in an ion-exchange membrane-based extractive fermentation system was examined. The exchange isotherms of anion exchange resins for lactic acid recovered were measured batchwise, and the exchange-desorption kinetics of lactic acid passing through the exchange column was investigated. The determined typical breakthrough and elution curves were measured and simulated by conventional mode. The mass transfer coefficients were identified by numberical method. The effects of the velocity of the fluid on the dynamics were studied. Aqueous NaOH solution was found to be the best solvent for elution. An experiment on anioun exchange from clarified lactic acid fermentation broth was carried out to obtain knowledge of the performance of the ion exchange system from a borth. The ion-exchange mass-transfer coefficient and efficiency from the fermentation broth is found to be lower when compared with aqueous solutions of pure lactic acid. The results show that the separation method with anion exchange resins may be used in the production of lactic acid by fermentation.© 1995 John Wiley & Sons, Inc.
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    Fundamental denitrification kinetic studies with Pseudomonas denitrificans (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 26-41 
    Details
    ISSN: 0006-3592
    Keywords: nitrate ; nitrite ; denitrification ; kinetics ; T effects ; pH effects ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fundamental kinetic studies on the reduction of nitrate, nitrite, and their mixtures were performed with a strain of Pseudomonas denitrificans (ATCC 13867). Methanol served as the carbon source and was supplied in excess (2:1 mole ratio relative to nitrate and/or nitrite). Nitrate and nitrite served as terminal electron acceptors as well as sources of nitrogen for biomass synthesis. The results were explained under the assumption that respiration is a growth-associated process. It was found that the sequence of complete reduction of nitrate to nitrogen gas is via nitrite and nitrous oxide.It was found that the specific growth rate of the biomass on either nitrate or nitrite follows Andrews inhibitory kinetics and nitrite is more inhibitory than nitrate. It was also found that the culture has severe maintenance requirements which can be described by Herbert's model, i.e., by self-oxidation of portions of the biomass. The specific maintenance rates at 30°C and pH 7.1 were found to be equal to about 28% of the maximum specific growth rate on nitrate and 23% of the maximum specific growth rate on nitrite. Nitrate and nitrite were found to be involved in a cross-inhibitory noncompetitive kinetic interaction. The extent of this interaction is negligible when the presence of nitrite is low but is considerable when nitrite is present at levels above 15 mg/L.Studies on the effect of temperature have shown that the culture cannot grow at temperatures above 40°C. The optimal temperature for nitrate or nitrite reduction was found to be about 38°C. Using an Arrhenius expression to describe the effect of temperature on the specific growth rates, it was found that the activation energy for the use of nitrate by the culture is 8.6 kcal/mol and 7.21 kcal/mol for nitrite. Arrhenius-type expressions were also used in describing the effect of temperature on each of the parameters appearing in the specific growth rate expressions. Studies on the effect of pH at 30°C have shown that the culture reduces nitrate optimally at a pH between 7.4 and 7.6, and nitrite at a pH between 7.2 and 7.3. © 1995 John Wiley & Sons, Inc.
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    Kinetics and mechanisms of the low-temperature degradation of cellulose (1994)
    Springer
    Cellulose 1 (1994), S. 26-56 
    Details
    ISSN: 1572-882X
    Keywords: low-temperature degradation ; kinetics ; mechanisms ; electrical insulation ; transformers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A critical review is given of the degradation of cellulose in the low-temperature region (below about 300°C) of power transformer operation. The large number of kinetic studies, under a variety of environmental conditions from Kraft paper in insulating oil, to cotton and paper in oxygen, are considered in terms of a first-order polymer chain scission model. In many cases, the data are replotted to suit the model. A common activation energy of 111±6 kjmol−1 is calculated and it is shown that the pre-exponential factor, rather than the activation energy, is sensitive to the oxidizing nature of the environment and the susceptibility to degradation of the material. The chemical mechanisms of degradation are reviewed, and conclusions and recommendations are made regarding chemical condition monitoring and life prediction of electrical insulation.
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    Growth characteristics of Geotrichum ingens on propionic acid and acetic acid in batch and continuous culture (1994)
    Springer
    World journal of microbiology and biotechnology 10 (1994), S. 505-509 
    Details
    ISSN: 1573-0972
    Keywords: Acetic acid ; chemostat ; Geotrichum ingens ; growth ; inhibition ; kinetics ; monocarboxylic acids ; propionic acid ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Growth of Geotrichum ingens in batch cultures was completely inhibited by 47 g acetic acid/l or 33 g propionic acid/I. With mixtures of acetic and propionic acids, however, growth only ceased at 55 g/l. Acetic acid inhibited growth linearly, whereas propionic acid inhibited growth non-linearly. In continuous culture, two steady states at each dilution rate were observed at high dilution rates for acetic acid and propionic acid. The highest yield coefficient (0.69 g cells/g substrate) was achieved with propionic acid as substrate. On both substrates and their mixtures, the protein content of the biomass increased when the dilution rate was increased.
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    Kinetic analysis of microbial sulfate reduction by desulfovibrio desulfuricans in an anaerobic upflow porous media biofilm reactor (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 267-274 
    Details
    ISSN: 0006-3592
    Keywords: microbial souring ; sulfate reduction ; porous media ; kinetics ; stoichiometry ; transport phenomena ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An anaerobic upflow porous media biofilm reactor was designed to study the kinetics and stoichiometry of hydrogen sulfide production by the sulfate-reducing bacterium (SRB) Desulfovibrio desulfuricans (ATCC 5575) as the first step for the modeling and control of formation souring (H2S) in oil field porous media. The reactor was a packed bed (50 × 5.5 cm) tubular reactor. Sea sand (140 to 375 μm) was used as the porous media. The initial indication of souring was the appearance of well-separated black spots (precipitates of iron sulfide) in the sand bed. The blackened zones expanded radially and upward through the column. New spots also appeared and expanded into the cone shapes. Lactate (substrate) was depleted and hydrogen sulfide appeared in the effluent.Analysis of the pseudo-steady state column shows that there were concentration gradients for lactate and hydrogen sulfide along the column. The results indicate that most of the lactate was consumed at the front part of the column. Measurements of SRB biomass on the solid phase (sand) and in the liquid phase indicate that the maximum concentration of SRB biomass resided at the front part of the column while the maximum in the liquid phase occurred further downstream. The stoichiometry regarding lactate consumption and hydrogen sulfide production observed in the porous media reactor was different from that in a chemostat. After analyzing the radial dispersion coefficient for the SRB in porous media and kinetics of microbial growth, it was deduced that transport phenomena dominate the souring process in our porous media reactor system. © 1994 John Wiley & Sons, Inc.
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    Kinetic investigation of microbial souring in porous media using microbial consortia from oil reservoirs (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 263-269 
    Details
    ISSN: 0006-3592
    Keywords: microbial souring ; sulfate reduction ; porous media ; kinetics ; biotransformation ; oil reservoir ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Microbial souring (H2S production) in porous media was investigated in an anaerobic upflow porous media reactor at 60°C using microbial consortia obtained from oil reservoirs. Multiple carbon sources (formate, acetate, propionate, iso- and n-butyrates) found in reservoir waters as well as sulfate as the electron acceptor was used. Kinetics and rates of souring in the reactor system were analyzed. Higher volumetric substrate consumption rates (organic acids and sulfate) and a higher volumetric H2S production rate were found at the from part of the reactor column after H2S production had stabilized. Concentration gradients for the substrates (organic acids and sulfate) and H2S were generated along the column. Biomass accumulation throughout the entire column was observed. The average specific sulfate reduction rate (H2S production rate) in the present reactor after H2S production had stabilized was calculated to be 11062 ±2.22 mg sulfate-S/day g biomass. © 1994 John Wiley & Sons, Inc.
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    Morphological kinetics and distribution in somatic embryo cultures (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 368-378 
    Details
    ISSN: 0006-3592
    Keywords: Daucus carota L. ; embryos ; kinetics ; morphology ; pattern recognition ; image analysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The environmental effects on developing somatic embryos should be characterized not only by the growth based on biomass, but also by the morphological properties and size. We have previously developed a discrete classifier to separate developing embryos into distinct morphological classes. In this study, a continuous descriptor using the distributions of magnitude of features representing morphological characteristics and size information was used to describe the developing embryo populations. The identity of the population was examined by comparing either the distributions of all features or key features. The method was applied to characterize the kinetics of carrot embryo populations cultivated in the presence and absence of triiodobenzoic acid(TIBA), an inhibitor of auxin polar transport. Optimal sample size for morphological characterization was determined by the invariance of feature distributions with further increase in sample size. The overall growth and substrate consumption kinetics were only slightly affected by the presence of TIBA. However, the distribution of morphological features was significantly affected. The features showing the highest statistical significance were related to those corresponding to the roughness. The continuous descriptor for characterizing developing embryo population is potentially useful for quality control in large-scale operations. © 1994 John Wiley & Sons, Inc.
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    Catabolic control of hybridoma cells by glucose and glutamine limited fed batch cultures (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 808-818 
    Details
    ISSN: 0006-3592
    Keywords: fed batch ; substrate limitation ; energy metabolism ; kinetics ; overflow metabolism ; growth rate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Substrate limited fed batch cultures were used to study growth and overflow metabolism in hybridoma cells. A glucose limited fed batch, a glutamine limited fed batch, and a combined glucose and glutamine limited red batch culture were compared with batch cultures. In all cultures μ reaches its maximum early during growth and decreases thereafter so that no exponential growth and decreases thereafter so that no exponential growth rate limiting, although the glutamine concentration (〉0.085mM) was lower than reported Ks vales and glucose was below 0.9mM; but some other nutrients (s) was the cause as verified by simulations. Slightly more cells and antibodies were produced in the combined fed batch compared with the batch culture. The specific rates for consumption of glucose and glutamine were dramatically influenced in fed batch cultures resulting in major metabolic changes. Glucose limitation decreased lactate formation, but increased glutamine consumption and ammonium formation. Glutamine limitation decreased ammonium and alanine formation of lactate, alanine, and ammonium was negligible in the dual-substrate limited fed batch culture. The efficiency of the energy metabolism increased, as judged by the increase in the cellular yield coefficient for glucose by 100% and for glutamine by 150% and by the change in the metabolic ratios lac/glc, ala/ln, and NHx/ln, in the combined fed culture. The data indicate that a larger proportion of consumed glutamine enters the TCA cycle through the glutamate dehydrogenase pathway, which releases more energy from glutamine than the transamination pathway. We suggest that the main reasons for these changes are decreased uptake rates of glucose and glutamine, which in turn lead to a reduction of the pyruvate pool and a restriction of the flux through glutaminase and lactate dehydrogenase. There appears to be potential for further cell growth in the dual-substrate-limited fed batch culture as judged by a comparison of μ in the different cultures. © 1994 John Wiley & Sons, Inc.
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    Production of somatic embryos in a helical ribbon impeller bioreactor (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 930-943 
    Details
    ISSN: 0006-3592
    Keywords: Eschscholtzia californica ; embryogenesis ; somatic embryos ; bioreactor ; macronutrients ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Embryogenic cultures of a transformed Eschscholtzia californica cell line were carried out in a 11-L helical ribbon impeller bioreactor operated under various conditions to evaluate the performance of this equipment for somatic embryo (SE) production. All bioreactor cultures produced SE suspensions with maximum concentrations at least comparable to those obtained from flask control cultures (∼8-13 SE · mL-;1). However, an increase of the mixingspeed, from 60 to 100 rpm, and low sparging rate (∼0.05 VVM, kL a ∼ 6.1 h-;1) for dissolved oxygen concentration (DO) control yielded poorer quality embryogenic cultures. The negative effects on SE production were attributed mainly to the low but excessive shear experienced by the embryogenic cells and/or embryoforming aggregates. High DO (∼60% of air saturation) conditions favored undifferentrated biomass production and high nutrient uptake rates at the expense of the slower SE differentiation process in both flask and bioreactor cultures. Too low DO (-5-10%) inhibited biomass and SE production. The best production of SE (∼44 SE · mL-1 or ∼757 SE · g dw-1 · d-1) was achieved by operating the bioreactor at 60 rpm while controlling DO at ∼20%by surface oxygenation only (0.05 VVM, kL a ∼ 1.4 h-;1). This production was found to be a biomass production/growth-associated process and was mainly limited by the availability of extracellular phosphate, magnesium, nitrogen salts, and carbohydrates. © 1994 John Wiley & Sons, Inc.
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    DSC and protein-based time-temperature integrators: Case study of α-amylase stabilized by polyols and/or sugar (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 859-865 
    Details
    ISSN: 0006-3592
    Keywords: differential scanning calorimetry ; kinetics ; time-temperature integrators ; protein thermostability ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Differential scanning calorimetry (DSC) was used as a tool for rapid assay of the thermostability of two Bacillus sp. α-amylases and horseradish peroxidase as a function of the concentration of glycerol, sorbitol, and sucrose. In this screening study, the DSC peak temperature proved to be a good measure of protein thermostability. By means of isothermal heating experiments, the kinetics of heat decay of B. amyloliquefaciens α-amylase were studied by following the course of the DSC peak area (heat exchange (ΔH/wt)) as a function of time. The high stability of this enzyme in the presence of polyolic alcohols or carbohydrates allowed working at temperatures as high as 127°C. The results of this study can have particular relevance with regard to research on and development of protein-based time-temperature integrators (TTls) for evaluating heat pasteurization or sterilization treatments of foods or pharmaceutical products. The use of the DSC peak area (ΔH.wt) as TTI-response was validated in experiments with a time-variable temperature profile. Finally, it was shown how the results of such non-isothermal experiments can even be used for (re-) estimation of the protein decay kinetic parameters (k, EA). © 1994 John Wiley & Sons, Inc.
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    Modeling hexavalent chromium reduction in Escherichia coli 33456 (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 293-300 
    Details
    ISSN: 0006-3592
    Keywords: chromium ; Escherichia coli microbial reduction ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model based on te analysis of the mechanism of enzymatic reactions was developed to characterize the rate and extent of microbial reduction of hexavalent chromium in Escherichia coli 33456. A finite reduction capacity (Rc) was proposed and incorporated into the enzymatic model to regulate the toxicity effect on cells due to the oxidizing power of Cr(VI). The parameter values were determined by nonlinear least-square analysis using experimental data of anaerobic cultures. The obtained parameters were then used to predict Cr(VI) reduction in aerobic cultures along with a modification term of uncompetitive inhibition from molecular oxygen. The applicability of the developed model was demonstrated through excellent prediction of the results of batch studies conducted over range of initial Cr(VI) concentrations, initial cell densities, and DO levels. A sensitivity analysis revealed that the parameters obtained using the experimental data were unique, and neither change in Kc, the half-velocity constant, at high initial Cr(VI) concentrations nor change in Rc, the reduction capacity, at low initial Cr(VI) concentrations was sensitive to model prediction. © 1994 John Wiley & Sons, Inc.
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    Leuconostoc mesenteroides growth kinetics with application to bacterial profile modification (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 865-873 
    Details
    ISSN: 0006-3592
    Keywords: Leuconostoc mesenteroides ; dextran ; kinetics ; bacterial profile modification ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bacterial profile modification (BPM) is being developed as an oil recovery technique that uses bacteria to selectively plug oil depleted zones within a reservoir to divert displacing fluids (typically water) into oil-rich zones. Leuconostoc mesenteroides, which produces dextran when supplied with sucrose, is a bacterium that is technically feasible for use in profile modification. However, the technique requires controlled bacterial growth to produce selective plugging.A kinetic model for the production of cells and polysaccharides has been developed for L. mesenteroides bacteria. This model, based on data from batch growth experiments, predicts saccharide utilization, cell generation, and dextran production. The underlying mechanism is the extracellular breakdown of sucrose into glucose and fructose and the subsequent production of polysaccharide (dextran). The monosaccharides are then available for growth. Accompanying sucrose consumption is the utilization of yeast extract. The cell requires a complex media that is provided by yeast extract as a source of vitamins and amino acids. Varying the concentration ratio of yeast extract to sucrose in the growth media provides a means of controlling the amount of polymer produced per cell. Consequently, in situ bacteria growth can be controlled by the manipulation of nutrient media composition, thereby providing the ability to create an overall strategy for the use of L. mesenteroides bacteria for profile modification.
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    Model of the anaerobic metabolism of the biological phosphorus removal process: Stoichiometry and pH influence (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 461-470 
    Details
    ISSN: 0006-3592
    Keywords: phosphorus removal ; metabolic model ; stoichiometry ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the anaerobic phase of a biological phosphorus removal process, acetate is taken up and converted to PHB utilizing both energy generated in the degradation of polyphosphate to phosphate, which is released, and energy generated in the conversion of glycogen to poly-β-hydroxy butyrate (PHB). The phosphate/acetate ratio cannot be considered a metabolic constant, because the energy requirement for the uptake of acetate is strongly influenced by the pH value. The observed phosphate/acetate ratio shows a variation of 0.25 to 0.75 P-mol/C-mol in a pH range of 5.5 to 8.5. It is shown that stored glycogen takes part in the metabolism to provide reduction equivalents and energy for the conversion of acetate to PHB. A structured metabolic model, based on glycogen as the source of the reduction equivalents in the anaerobic phase and the effect of the pH on the energy requirement of the uptake of acetate, is developed. The model explains the experimental results satisfactorily. © 1994 John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/bit.260430605
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    Solvation of CBZ-amino acid nitrophenyl esters in organic media and the kinetics of their transesterification by subtilisin (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 1081-1086 
    Details
    ISSN: 0006-3592
    Keywords: solvation ; organic media ; kinetics ; subtilisin ; thermodynamics ; solubility ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Subtilisin Carlsberg adsorbed on silica particles has been used to catalyze the transesterification of CBZ-Ala-ONp and CBZ-Leu-ONp with 1-butanol in organic systems preequilibrated to water activity of 0.93. Initial reaction rates are conveniently followed by extraction of the released nitrophenol into an alkaline aqueous phase. Kinetic parameters were determined for varied ester concentrations in toluene, isopropyl ether, and hexane. The effect of solvent on substrate solvation was determined by solubility measurements. Much of the observed effect of solvent on Vm/Km may be accounted for by solvation differences. The residual effect of solvent on Km, after discounting solvation differences, is completely opposite to the apparent trend. © 1994 John Wiley & Sons, Inc.
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    Heterogeneity of biofilms in rotating annular reactors: Occurrence, structure, and consequences (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 194-204 
    Details
    ISSN: 0006-3592
    Keywords: biofilm ; biofilm reactors ; structure ; heterogeneity ; kinetics ; modeling ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A rotating annular reactor (Roto Torque) was used for qualitative and quantitative studied on biofilm heterogeneity. In contrast to the classic image of biofilms as smooth, homogeneous layers of biomass on a substratum, studies using various pure and mixed cultures consistently revealed more-dimensional structures that resembled dunes and ridges, among others. These heterogeneities were categorized and their underlying causes analyzed. Contrary to expectations, motility of the microorganisms not a decisive factor in determining biofilm homogeneity. Small Variations in substratum geometry homogeneity. Small variations in substratum geometry and flow patterns were clearly reflected in the biofilm pattern. Nonhomogeneous flow and shear patterns in the reactor, together with inadequate mixing resulted in significant, position-dependent differences in surface growth. It was therefore not possible to take representative samples of the attached biomass. Like many other types of reactors, the Roto Torque reactor is valuable for qualitative and morphological biofilm experiments but less suitable for quantitative physiological and kinetics studies using attached microorganisms. © 1994 John Wiley & Sons, Inc.
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    Equilibrium and kinetic studies on reversible and irreversible denaturation of micrococcal nuclease (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 276-282 
    Details
    ISSN: 0006-3592
    Keywords: nuclease ; deactivation, irreversible ; kinetics ; denaturation reversible ; sucrose ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of pH and temperature on the thermal denaturation of micrococcal nuclease wer4e investigated. The ranges employed were between pH3.30 and pH9.70 and between 10°C and 85°C, respectively. The reversible denaturation involved in the whole process was clearly discriminated from the irreversible one. The former took place with a large enthalpy change of 384 kJ mol-1 at pH 9.70, where the enzyme exhibited it s maximum activity. The latter probably led to aggregation because the successive long incubation after complete deactivation caused precipitation. A reasonable scheme explaining the process involving both denaturations was proposed and the kinetic on the irreversible deactivation was performed. It was revealed that the irreversible deactivation involved two types of reactions whose activation energies were relatively small: 22.2 kJ mol-1 and 18.8kJ mol-1. The presence of sucrose suppressed the reversible denaturation without significant influence on enthalpy change, whereas it affected little the irreversible deactivation kinetically. The effects of pH change and addition of sucrose on the denaturation were discussed thermodynamically, especially in terms of the entropy change. © 1994 John Wiley & Sons, Inc.
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    The kinetics and regulation of M-xylose transport in Candida utilis (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 357-360 
    Details
    ISSN: 1573-0972
    Keywords: Candida utilis ; inhibition ; kinetics ; regulation ; sugar ; transport ; xylose ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Low-affinity (K m=67.6±3.2 mM) and high-affinity (K m=1.9±1.2 mM) D-xylose transport occur in Candida utilis grown, respectively, on D-glucose or D-xylose. Starvation of glucose-grown cells decreases the K m value (10.5±2.6 mm). The high-affinity system appearing during starvation required protein synthesis and it was inactivated when cells were exposed to glucose, by a process independent of protein synthesis. High-affinity transport was accompanied by transient alkalinization of yeast suspensions, indicating that it is a proton symport, whereas low-affinity transport was not. Both systems, however, were inhibited by metabolic inhibitors and by replacing H2O in the transport assay with D2O, indicating that both may be proton symports. Glucose and acetic acid also inhibited both high-and low-affinity xylose transport.
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    Interaction of dichloromethane (methylene chloride) with the nitrous oxide reductase from Wolinella succinogenes (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 479-482 
    Details
    ISSN: 1573-0972
    Keywords: Benzyl viologen ; dichloromethane ; inhibitor ; kinetics ; nitrous oxide ; nitrous oxide reductase ; tetrachloromethane ; trichloromethane ; Wolinella succinogenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Nitrous oxide reductase from Wolinella succinogenes was tested for benzyl viologen cation (BV+)-chlorinated methane oxidoreductase activity, using di-, tri- and tetra-chloromethanes, and for the inhibition of BV+-N2O oxidoreductase activity by these chloromethanes. No BV+-chlorinated methane oxidoreductase activity was detected. Any such activity, if it exists, must be less than 0.1% of the BV+-N2O oxidoreductase activity of the enzyme. Inhibition of the BV+-N2O oxidoreductase activity by dichloromethane was detected and was apparently reversible and non-competitive, as is the case with the small metal-ligand type inhibitors of the enzyme (e.g. acettlene, azide, cyanide and carbon monoxide). Trichloromethane was a weaker inhibitor and inhibition was not detected with tetrachloromethane.
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    Loss of antibody productivity is highly reproducible in multiple hybridoma subclones (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 247-250 
    Details
    ISSN: 0006-3592
    Keywords: hybridoma ; antibody productivity ; kinetics ; instability ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An immunoglobulin G (IgG2b) producing hybridoma cell line (S3H5/γ2bA2) was cloned and subcloned. Twenty subclones were grown in parallel while being adapted in a stepwise fashion to serum-free medium. Following adaptation to serum-free medium, it was found that 16 of the 20 subclones remained at a relatively constant proportion of nonproducing cells. Three of the remaining subclones transiently deviated from this balance but eventually returned toward this population composition. One subclone continued to lose productivity. A population balance was reached at approximately 8% of the population being nonproducers. The loss of antibody productivity was thus highly reproducible. © 1993 John Wiley & Sons, Inc.
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    A three-phase pattern in growth, monoclonal antibody production, and metabolite exchange in a hybridoma bioreactor culture (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 133-139 
    Details
    ISSN: 0006-3592
    Keywords: hybridoma ; kinetics ; curve fitting ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The use of partial cubic spline data interpolation for the calculation of volumetric metabolite exchange rates suggested the existence of three distinct metabolic phases during bioreactor culture of a hybridoma cell line. During phase 1, a rapid amino acid uptake rate and ammonia release rate were observed. The growth rate was low and glutamine synthetase activity fell. In phase 2, maximum growth rate and minimum glutamine assimilation and ammonium production rates were observed. Attempts to corroborate the apparent ammonia assimilation in this phase using 15NH4Cl resulted in low incorporation rates into alanine and glutamine. Maximum glutamine synthetase activity took place during this period. Maximum antibody production rate was observed during phase 3 during which peaks in glutamine assimilation, ammonia release, and glutamine synthetase activity were observed. The apparent existence of the three phases prompted us to carry out Northern blot analysis of glutamine synthetase RNA at appropriate times during the process. This revealed a pattern of appearance and dis-appearance of mRNA consistent with the three phases indicated by the fermentation parameters. © 1993 John Wiley & Sons, Inc.
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    Activated sludge process performance using a multistage tower aeration tank (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 315-325 
    Details
    ISSN: 0006-3592
    Keywords: multistage tower aeration tank ; activated sludge process ; kinetics ; Peclet number ; dispersion model ; simulation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This study's objective was to clarify both experimentally and theoretically whether a vertical multistage tower aeration tank system is advantageous as compared with a completely mixed system, particularly with respect to purification efficiency, sludge settleability, and excess sludge production. In comparing the two systems: (1) purification efficiency in the multistage tower aeration system with partial fluid mixing with a large Peclet number was higher than in a corresponding completely mixed system for all applied organic loadings; (2) the multistage tower aeration system had some definite advantages with respect to sludge settleability and excess sludge production; (3) the activated sludge system's higher performance with partial fluid mixing was shown quantitatively with the axial dispersion model in conjunction with growth kinetics which involved rapid uptake such as biosorption and subsequent oxidative biodegradation processes of organic substances. © 1993 John Wiley & Sons, Inc.
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    A new approach for modeling cellulase-cellulose adsorption and the kinetics of the enzymatic hydrolysis of microcrystalline cellulose (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 469-479 
    Details
    ISSN: 0006-3592
    Keywords: cellulase ; cellulose ; adsorption ; kinetics ; mathematical model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two fractions of substrate in microcrystalline cellulose which differ in their adsorption capacities for the cellulases and their susceptibility to enzymatic attack have been identified. On the basis of a two-substrate hypothesis, mathematical models to describe enzyme adsorption and the kinetics of hydrolysis have been derived. A new nonequilibrium approach was chosen to predict cellulase-cellulose adsorption. A maximum binding capacity of 76 mg protein per gram substrate and a half-maximum saturation constant of 26 filter paper units (FPU) per gram substrate have been calculated, and a linear relationship of hydrolysis rate vs. adsorbed protein has been found. The fraction of substrate more easily hydrolyzed, as calculated from hydrolysis data, represents 19% of the total effective substrate concentration. This fraction is only slightly different from that of other celluloses and has been estimated to be 27% and 30% for NaOH- and H3PO4-swollen cellulose, respectively. The effective substrate concentration is equal to the maximum amount of the substrate which can be converted during exhaustive hydrolysis. This in turn is determined by the overall degradability of the substrate by the cellulases (85-90% for microcrystalline cellulose) and by the cellobiose concentration during hydrolysis. The kinetic model is based on a summation of two integrated first-order reactions with respect to the effective substrate concentration. Furthermore, it includes the principal factors influencing the reaction rates: the ratio of filter paper and β-glucosidase units per gram substrate and the initial substrate concentration. © 1993 John Wiley & Sons, Inc.
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    Kinetic study of lipase catalyzed esterification reactions in water-in-oil microemulsions (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 931-937 
    Details
    ISSN: 0006-3592
    Keywords: lipase ; microemulsions ; reverse micelles ; esterification ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of the esterification of lauric acid by (-)menthol, catalyzed by Penicillium simplicissimum lipase, was studied in water/bis-(2-ethylhexyl)sulfosuccinate sodium salt (AOT)/isooctane microemulsions. Due to their low water content, microemulsions assist in reversing the direction of lipase activity, favoring synthetic reactions. The kinetics of this synthesis follows a Ping-Pong Bi—Bi mechanism. The values of all apparent kinetic parameters were determined. The theoretical model for the expression of enzymic activity in reverse micelles, proposed by Verhaert et al. (Verhaert, R., Hilhorst, R., Vermüe, M., Schaafsma, T. J., Veeger, C. 1990. Eur. J. Biochem. 187: 59-72) was extended to express the lipase activity in an esterification reaction involving two hydrophobic substrates in microemulsion systems. The model takes into account the partitioning of the substrates between the various phases and allows the calculation of the intrinsic kinetic constants. The experimental results showing the dependence of the initial velocity on the hydration ratio, Wo = [H2O]/[AOT], of the reverse micelles, were in accordance with the theoretically predicted pattern. © 1993 John Wiley & Sons, Inc.
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    Comparison of substrate utilization and growth kinetics between immobilized and suspended Pseudomonas cells (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 370-379 
    Details
    ISSN: 0006-3592
    Keywords: immobilized cell ; kinetics ; Monod growth Kinetics ; substrate utilization kinetics ; physicochemical effects in immobilized cell culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A methodology is described for measurement if immobilized and suspended cell growth and substrate utilization kinetics parameters. Substrate utilization and growth kinetics were compared between immobilized and suspended cells for toluene degrading Pseudomonas strains K3-2 and 2,4-dichlorophenoxyacetic acid (2,4-D) degrading strain DBO131(pR0101), respectively. Kinetic parameters were estimated using nonlinear parameter estimation methods and compared between the immobilized and suspended Pseudomonas cells to determine the effect of immobilization on cellular growth and substrate utilization. Factors influencing the experimental design included calculated oxygen flux rates, primary carbon substrate flux rates, and shear stresses on the immobilize cell. Statistical interpretation of the cellular reaction rate parameters indicates that only the growth kinetics of the toluene system were significantly altered upon immobilization. Substrate utilization kinetics remained unchanged upon immobilization. The substrate growth associated half-saturation constant (Kg) for the toluene system increased by 30-fold and the maximum specific growth rate (μmax) decreased by 2-fold upon immobilization. Implication of these results for experimental determination of cellular kinetic parameters and for immobilization cell bioreactors design are discussed. © 1993 John Wiley & Sons, Inc.
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    Kinetics of enzymatic degradation of cyanide (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 629-634 
    Details
    ISSN: 0006-3592
    Keywords: biocatalyst ; cyanide degradation ; immobilized enzyme ; wastewaters ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: CYANIDASE@ is a new enzyme preparation capable of degrading cyanide in industrial wastewaters to ammonia and formate in an apparently one-step reaction, down to very low concentrations. This enzyme has both a high selectivity and affinity toward cyanide. A granular form of the biocatalyst was used in a recirculation fixed bed reactor in order to characterize the new biocatalyst with respect to pH, ionic strength, common ions normally present in wastewaters, mass transfer effects, and temperature. Long term stability was investigated. The kinetics of the enzymatic degradation of cyanide were studied in a batch reactor using the powdered immobilized enzyme preparation and modeled using a simple Michaelis-Menten equation.
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    A structured model for simulation of cultures of the cyanobacterium Spirulina platensis in photobioreactors: I. Coupling between light transfer and growth kinetics (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 817-825 
    Details
    ISSN: 0006-3592
    Keywords: modeling ; kinetics ; cyanobacteria ; photobioreactors ; radiative transfer ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The study of the interactions between physical limitation by light and biological limitations in photobioreactors leads to very complex partial differential equations. Modeling of light transfer and kinetics and the assessment of radiant energy absorded in photoreactors require an equation including two parameters for light absorption and scattering in the culture medium. In this article, a simple model based on the simplified, monodimensional equation of Schuster for radiative transfer is discussed. This approach provides a simple way to determine a working illuminated volume in which growth occurs, therefore allowing indentification of kinetic parameters. These parameters might then be extended to the analysis of more complex geometries such as cylindrical reactors. Moreover, this model allows the behavior of batch or continuous cultures of cyanobacteria under light and mineral limitations to be predicted. © 1992 John Wiley & Sons, Inc.
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    Accurate pseudoanalytical solution for steady-state biofilms (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 790-793 
    Details
    ISSN: 0006-3592
    Keywords: biofilms ; kinetics ; steady state ; pseudoanalytical solution ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An extremely accurate pseudoanalytical solution for the flux of substrate into a steady-state biofilm is developed. The standard deviations between the substrate fluxes computed from the pseudoanalytical solution and the numerical solution were less than 2.6%. Additional advantages of the pseudoanalytical solution are that it has no inaccuracies around Smin* = 1 and it is composed of single continuous functions applicable to the whole Smin* region.
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    Enzymatic reaction kinetic: Comparison in an organic solvent and in supercritical carbon dioxide (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 329-333 
    Details
    ISSN: 0006-3592
    Keywords: lipase ; supercritical carbon dioxide ; kinetics ; esterification ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Myristic acid esterification has been performed by an immobilized lipase from Mucor Miehei both in n-hexane and in supercritical carbon dioxide (SCCO2). The enzyme is stable in SCCO2 at 15 MPa and 323 K. The reaction rate is influenced by the concentration of water and by the reaction medium composition. A reaction mechanism is proposed, and kinetic parameters are determined at 12.5 MPa and 313 K. Maxium velocity appears 1.5-fold higher in SCCO2 than in n-hexane; however, as solubility of myristic acid is greater in n-hexane, it is not yet definitively clear that the supercritical medium is more favorable than the classical organic solvent for this type of enzyme reaction.
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    Factors affecting microbial sulfate reduction by Desulfovibrio desulfuricans in continuous culture: Limiting nutrients and sulfide concentration (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 725-734 
    Details
    ISSN: 0006-3592
    Keywords: Desulfovibrio desulfuricans ; stoichiomentry ; kinetics ; microbial sulfate reduction ; sulfate limitation ; nitrogen limitation ; sulfide inhibition ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of sulfate and nitrogen concentrations of the rate and stoichiometry of microbial sulfate reduction were investigated for Desulfovibrio desulfuricans grown on lactate and sulfate in a chemostat at pH 7.0. Maximum specific growth rates (μmax), half-saturation coefficients (Ksul), and cell yield (Yc/Lac) of 0.344 ± 0.007 and 0.352 ± 0.003 h -1, 1.8 ± 0.3 and 1.0 ± 0.2 mg/L, and 0.020 ± 0.003 and 0.017 ± 0.003 g cell/g lactate, respectively, were obtained under sulfate-limiting conditions at 35°C and 43°C. Maintenance energy requirements for D. desulfuricans were significant under sulfate-limiting conditions. The extent of extracellular polymeric substance (EPS) produced was related to the carbon: nitrogen ratio in the medium. EPS production rate increased with decreased nitrogen loading rate. Nitrogen starvation also resulted in decreased cell size of D. desulfuricans. The limiting C : N ratio (w/w) for D. desulfuricans was in the range of 45 : 1 to 120 : 1. Effects of sulfide on microbial sulfate reduction, cell size, and biomass production were also ivestigated at pH 7.0. Fifty percent inhibition of lactate utilization occurred at a total sulfide concentration of approximately 500 mg/L. The cell size of D. desulfuricans decreased with increasing total sulfide concentration. Sulfide inhibition of D. desulfuricans was observed to be a reversible process. © 1992 John Wiley & Sons, Inc.
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    A structured model for simulation of cultures of the cyanobacterium Spirulina platensis in photobioreactors: II. Identification of kinetic parameters under light and mineral limitations (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 826-834 
    Details
    ISSN: 0006-3592
    Keywords: Modeling ; kinetics ; cyanobacteria ; photobioreactors ; Spirulina platensis ; mineral limitations ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A structured model for the culture of cyanobacteria in photobioreactors is developed on the basis of Schuster's approximations for radiative light transfer. This model is therefore limited to monodimensional geometries and kinetic aspects.Light-harvesting pigments play a crucial role in defining the profile of radiative transfer inside the culture medium and in controlling the metabolism, particularly the metabolic deviations induced by mineral limitations. Modeling therefore requires the biomass to be divided into several compartments, among which the light-harvesting compartment allows a working illuminated volume to be defined within the photobioreactor. This volume may change during batch cultures, largely decreasing as pigment concentration increases during growth but increasing as pigments are consumed during mineral limitation. This approach enables, in photobioreactors of simple parallelepipedic, geometries, kinetic parameters to be determined with high accuracy; this may then be extended to vessels of more complex geometries, such as cylindrical photobioreactors.The model is applied to controlled batch cultures of the cyanobacterium Spirulina platensis in parallelepipedic photobioreactors to assess its ability to predict the behavior of these microorganisms in conditions of light and mineral limitations. Results allowed the study of optimal operating condition for continuous cultures to be approached © 1992 John Wiley & Sons, Inc.
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    Protein immobilization to alumina supports: II. Papain immobilization to alumina via organophosphate linkers (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 1328-1336 
    Details
    ISSN: 0006-3592
    Keywords: immobilization ; papain ; alumina ; kinetics ; fluorescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Particulate aluminum oxides (alumina) were examined as supports for the immobilization of the proteolytic enzyme papain. Two alumina supports termed C1 and CPC were derivatized using organic phosphate linkers to create free carboxyl groups using a two-step process. Papain binding to these derivatized aluminas was performed using the water soluble carbodiimide 1-ethyl-3-(dimethylaminopropyl) carbodiimide. Reactions were optimal at 10 mM carbodiimide. The immobilized protein showed similar kinetic constants when compared to the solution protein. The pH dependence and thermal stability were essentially identical. The immobilized papain showed a blue shift in the intrinsic fluorescence emission maxima. Papain modified with the active site-specific fluorescent probe acrylodan showed overlapping emission maxima. These results are interpreted as retention of the hydrophobic environment of the active site with a perturbation in the structure of the rest of the protein caused by its association with the negatively charged surface. © 1992 John Wiley & Sons, Inc.
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    Effects of temperature and phosphorous concentration on microbial sulfate reduction by Desulfovibrio desulfuricans (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 1031-1042 
    Details
    ISSN: 0006-3592
    Keywords: D. desulfuricans ; sulfate reduction ; phosphorous limitation ; kinetics ; stoichiometry ; temperature effect ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of temperature and phosphorous concentration on the rate and the extent of microbial sulfate reduction with lactate as carbon and energy source were investigated for Desulfovibrio desulfuricans. The continuous culture experiments (chemostat) were conducted at pH 7.0 from 12 to 48°C. The maximum specific growth rate (μmax) was relatively constant in the range 25°C-43°C and dramatically decreased outside this temperature range. The half-saturation coefficient was minimum at 25°C. Cell yield was highest in the optimum temperature range (35°C-43°C) for growth. Maintenance energy requirements for D. desulfuricans were not significant. Two moles of lactate is consumed for every mole of sulfate reduced, and this stoichiometric ratio is not temperature dependent. Steady state rate and stoichiometric coefficients accurately predicted transient behavior during temperature shifts. The extent of extracellular polymeric substance (EPS) is related to the concentration of phosphorous in the medium. EPS production rate increased with decreased phosphorous loading rate. Failure to discriminate between cell and EPS formation by D. desulfuricans leads to significant overestimates of the cell yield. The limiting C:P ratio for D. desulfuricans was in the range of 400:1 to 800:1.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260391007
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    Comparison of specific rates of hybridoma growth and metabolism in batch and continuous cultures (1992)
    Springer
    Cytotechnology 10 (1992), S. 147-155 
    Details
    ISSN: 1573-0778
    Keywords: batch culture ; continuous culture ; hybridoma ; kinetics ; specific rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract For the mouse hybridoma cell line VO 208, kinetics of growth, consumption of glucose and glutamine, and production of lactate, ammonia and antibodies were compared in batch and continuous cultures. At a given specific growth rate, different metabolic activities were observed: a 40% lower glucose and glutamine consumption rate, but a 70% higher antibody production rate in continuous than in batch culture. Much higher metabolic rates were also measured during the initial lag phase of the batch culture. When representing the variation of the specific antibody production rate as a function of the specific growth rate, there was a positive association between growth and antibody production in the batch culture, but a negative association during the transient phase of the continuous culture. The kinetic differences between cellular metabolism in batch and continuous cultures may be result of modifications in the physiology and metabolism of cells which, in continuous cultures, were extensively exposed to glucose limitations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570891
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  • 75
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    Kinetic study of hybridoma cell growth in continuous culture: II. Behavior of producers and comparison to nonproducers (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 1020-1028 
    Details
    ISSN: 0006-3592
    Keywords: hybridoma ; cell culture ; continuous culture ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A hybridoma cell line, AFP-27-P, was cultivated in continuous culture under glucose-limited conditions. The viable cell concentration, dead-cell concentration, and cell volume all varied with the dilution rate. A model previously developed for a nonproducing clone of the same cell line, AFP-27-NP, was extended to describe the behavior of the cells. The relationship between the specific growth rate and glucose concentration is described by a function similar to the Monod model. A threshold glucose concentration and a minimum specific growth rate are incorporated; the model is meaningful only at glucose concentration and a minimum specific growth rate are incorporated; the model is meaningful only at glucose concentrations and specific growth rates above these levels. The relationship between the death rate and the glucose concentration is described by an inverted Monod-type function. Furthermore, the yield coefficient based on glucose is constant in the lower range of specific growth rates and changes to a new constant value in the upper range of specific growth rates. No maintenance term for glucose consumption is used; in the plot of specific glucose consumption rate vs. specific growth rate, the line intercepts the specific growth rate at a value close to the minimum growth rate. The productivity of antibody as a function of the specific growth rate is described by a mixed type model with a noon-growth-associated term and a negative-growth-associated term. The values for the model parameters were determined from regression analysis of the steady state data.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380910
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  • 76
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    Hydrolysis of inulin: A kinetic study of the reaction catalyzed by an inulinase from Aspergillus ficuum (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 575-579 
    Details
    ISSN: 0006-3592
    Keywords: inulin ; inulinase ; fructose ; enzymic hydrolysis ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A kinetic study of the hydrolysis of inulin was performed by using as catalyst a commercial inulinase from Aspergillus ficuum. The reaction was studied carrying out initial rate as well as time course measurements. Both inulinase and invertase activities of the enzyme were taken into account, and the corresponding kinetic parameters were determined in the temperature range 30-50°C. The activation energies of the turnover constant for inulinase and invertase activities were found to be similar (56-57 kJ · mol-1). The ratio S/I of invertase to inulinase activity was 1.6 regardless of temperature. The thermal degradation of the enzyme was also investigated up to 70°C, and an activation energy of 350-370 kJ · mol-1 was evaluated.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260370612
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  • 77
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    Kinetics and modeling of temperature effects on batch xanthan gum fermentation (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 567-574 
    Details
    ISSN: 0006-3592
    Keywords: xanthan fermentation ; temperature ; kinetics ; model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Batch fermentation kinetics of xanthan gum production from glucose by Xanthomonas campestris at temperatures between 22°C and 35°C were studied to evaluate temperature effects on cell growth and xanthan formation. These batch xanthan fermentations were modeled by the logistic equation for cell growth, the Luedeking-Piret equation for xanthan production, and a modified Luedeking-Piret equation for glucose consumption. Temperature dependence of the parameters in this model was evaluated. Growth-associated rate constants increased to a maximum at ∼30°C and then decreased to zero at ∼35°C. This temperature effect can be modeled using a square-root model. On the contrary, non-growth-associated rate constants increased with increasing temperature, following the Arrhenius relationship, in the entire temperature range studied. The model developed in this work fits the experimental data very well and can be used in a simulation study. However, due to the empirical nature of the model, the parameter values need to be reevaluated if the model is to be applied to different growth conditions.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260370611
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  • 78
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    Papain kinetics in the presence of a water-miscible organic solvent (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 967-972 
    Details
    ISSN: 0006-3592
    Keywords: papain ; organic solvent ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of various concentrations of a water-miscible organic solvent [a 7:3 (v/v) mixture of N, N dimethylformamide and dimethylsulfoxide] on the kinetics of papain have been investigated. The parameters kcat and Km for the amidase and esterase activity of papain using N-α-benzoyl-DL-arginine-p-nitroanilide (BAPNA) and N-α-benzoyl-L-arginine ethyl ester (BAEE) as substrates were determined. For both types of activity, kcat initially increased (up to about 15% solvent), and then decreased with increasing concentrations of organic solvent. In contrast, Km increased sharply with the organic solvent concentration. Active site titration at 0 and 50% solvent indicated no change in the amount of active enzyme. Fluorometric measurements of the emission spectrum of papain did not indicate any major conformational changes with increasing concentrations of organic solvent.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260371011
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  • 79
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    Kinetic data for the BM-5 insect cell line in repeated-batch suspension cultures (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 116-126 
    Details
    ISSN: 0006-3592
    Keywords: Bombyx mori ; repeated-batch ; kinetics ; suspension cultures ; nutritional requirements ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics and growth characteristics of the BM-5 insect cell line of Bombyx mori (silkworm) have been experimentally investigated in order to develop optimal growth protocols when these cells are used to produce large quantities of human proteins by recombinant baculoviruses. Experiments were performed in 200-mL spinner flasks, which were operated at 80 rpm with 0.3% methyl cellulose (MCL) added to the medium to protect the cells from shear stress. Exposure of the cells to varying nutrient and metabolite concentrations was accomplished through a repeated-batch mode of feeding. The results indicate that glutamine is a limiting nutrient and that lactate has an inhibitory effect on cell growth. Ammonia depletion from the medium was accompanied by uric acid accumulation suggesting that ammonia is converted to this metabolic product by the “uricotelic” and “nucleicolytic” metabolic pathways. With the examined medium formulation, glucose, fructose, and sucrose remained at high concentrations throughout the cultivation period.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260380203
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  • 80
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    Influence of inoculum age on hybridoma culture kinetics (1991)
    Springer
    Cytotechnology 5 (1991), S. 165-171 
    Details
    ISSN: 1573-0778
    Keywords: growth ; hybridoma ; inoculum age ; kinetics ; production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract To determine the influence of the inoculum age on the kinetics of hybridoma growth and metabolism, spinner flasks have been inoculated with cells previously propagated in T flasks for 43, 52, 62 and 71 hr respectively. Increasing the age of the inoculum is found to result in a longer lag phase, in a lower maximum specific growth rate and in a reduced maximal cell density. During the growth phase specific rates of glucose and glutamine uptake and of ammonia and lactate production are similar. However, with the older inoculum, much higher metabolic activities are observed during the lag phase. The production of antibodies is delayed with increasing inoculum age, but the final antibody concentrations are similar, which indicates a higher specific antibody production rate when inoculating with older cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00365433
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  • 81
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    Growth and protein production kinetics of a murine myeloma cell line transfected with the human growth hormone gene (1991)
    Springer
    Cytotechnology 5 (1991), S. 223-231 
    Details
    ISSN: 1573-0778
    Keywords: cell culture ; kinetics ; Ig promoter/enhancer ; plasmacytoma ; recombinant protein production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A model mammalian cell system for the production of recombinant proteins was investigated. Murine myeloma cells which had lost the ability to produce both heavy and light chain immunoglobulin molecules were transfected with a vector containing the immunoglobulin heavy chain promoter and enhancer elements linked to the human growth hormone gene. The growth kinetics of G32, a clonal isolate, were found to be similar to both the parent myeloma and hybridomas. However, production of hGH by G32 was growth associated, rather than as a secondary metabolite as is the case for hybridomas. In addition, G32 produced hGH at molar levels greater than most hybridomas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00556292
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  • 82
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    Kinetics of Dissolution of Limestone Slurries in Sulfuric Acid (1985)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 57 (1985), S. 882-883 
    Details
    ISSN: 0009-286X
    Keywords: Limestone slurries ; dissolution ; kinetics ; constant pH value ; stirred tank ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330571018
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  • 83
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    Effects of the interaction of porcine pancreatic lipase with AOT/isooctane reverse micelles on enzyme structure and function follow predictable patterns
    Amsterdam : Elsevier
    Enzyme and Microbial Technology 15 (1993), S. 944-949 
    Details
    ISSN: 0141-0229
    Keywords: Reverse micelles ; conformation ; kinetics ; lipase ; protein-membrane/interface interaction
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0141-0229(93)90170-7
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    Prediction of ester production in industrial beer fermentation
    Amsterdam : Elsevier
    Enzyme and Microbial Technology 16 (1994), S. 66-71 
    Details
    ISSN: 0141-0229
    Keywords: Esters ; beer ; fermentation ; industrial ; kinetics ; stirred-tank
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0141-0229(94)90111-2
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  • 85
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    Disaccharide production by glucoamylase in aqueous ether mixtures
    Amsterdam : Elsevier
    Enzyme and Microbial Technology 16 (1994), S. 383-387 
    Details
    ISSN: 0141-0229
    Keywords: 2-ethoxyethyl ether ; 2-methoxyethyl ether ; Glucoamylase ; disaccharides ; kinetics ; solubility ; stability ; triethylene glycol dimethyl ether ; trisaccharides
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0141-0229(94)90152-X
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  • 86
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    Product inhibition of fermentation of xylose to ethanol by free and immobilized Pichia stipitis
    Amsterdam : Elsevier
    Enzyme and Microbial Technology 16 (1994), S. 622-626 
    Details
    ISSN: 0141-0229
    Keywords: Pichia stipitis ; d-xylose ; immobilization ; inhibition ; kinetics ; microcalorimetry
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0141-0229(94)90129-5
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  • 87
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    Effect of the organic volumetric loading rate on soluble COD removal in down-flow anaerobic fixed-bed reactors
    Amsterdam : Elsevier
    Bioresource Technology 47 (1994), S. 173-176 
    Details
    ISSN: 0960-8524
    Keywords: Down-flow anaerobic reactors ; cattle wastes ; kinetics ; piggery waste ; torula yeast waste
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0960-8524(94)90117-1
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  • 88
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    Phenol oxidation in supercritical water
    Amsterdam : Elsevier
    The @Journal of Supercritical Fluids 3 (1990), S. 240-248 
    Details
    ISSN: 0896-8446
    Keywords: kinetics ; oxidation ; phenol ; reaction product ; supercritical water
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0896-8446(90)90029-L
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  • 89
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    The effect of salts on hydrolysis in supercritical and near-critical water: Reactivity and availability
    Amsterdam : Elsevier
    The @Journal of Supercritical Fluids 5 (1992), S. 163-168 
    Details
    ISSN: 0896-8446
    Keywords: hydrolysis ; kinetics ; salt effects ; solvent effects ; supercritical ; water
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0896-8446(92)90003-3
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  • 90
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    Hydrolysis in supercritical water: Solvent effects as a probe of the reaction mechanism
    Amsterdam : Elsevier
    The @Journal of Supercritical Fluids 3 (1990), S. 222-227 
    Details
    ISSN: 0896-8446
    Keywords: hydrolysis ; kinetics ; mechanism ; reactions ; supercritical water
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0896-8446(90)90026-I
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  • 91
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    Mechanism and kinetics of the acid-catalyzed dehydration of ethanol in supercritical water
    Amsterdam : Elsevier
    The @Journal of Supercritical Fluids 3 (1990), S. 228-232 
    Details
    ISSN: 0896-8446
    Keywords: E2 mechanism ; acid-catalysis ; dehydration ; ethanol ; kinetics ; mechanism ; parameter estimation ; supercritical water
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0896-8446(90)90027-J
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