bluuebunny/crossref_metadata_2025_split huggingface dataset:
Purification of municipal wastewater by subsequent reverse osmosis and anaerobic digestion
Authors: Van Den Heuvel J. C. , Zoetemeyer R. J. , Boelhouwer C. 
Published: December 2004

AbstractExperiments are described in which municipal wastewater is submitted to reverse osmosis. During a test period of two months a tubular apparatus, operated batchwise, maintained its original flux and rejection, the permeate being of good quality as a raw material for drinking water. The wastewater was concentrated 7.7 times. Continuous anaerobic digestion of the brine removed over 90% of the BOD evolving the expected amount of methane. The overall process is considered in its context of environmental and energetic aspects and is compared with a conventional treatment. This reveals clear perspectives for practical application in urban areas.
Enzymatic modification of vegetable protein: Immobilization of Penicillium duponti enzyme on reconstituted collagen and the use of the immobilized‐enzyme complex for solubilizing vegetable protein in a recycle reactor
Authors: Adu‐Amankwa B. , Constantinides A. , Vieth W. R. 
Published: December 2004

AbstractPenicillium duponti enzyme was immobilized on reconstituted collagen by macromolecular complication, impregnation, and covalent crosslinking techniques. The immobilization of the enzyme on collagen has a twofold purpose: (1) providing a protein microenvironment for the proteolytic enzyme; and (2) extending the useful life the enzyme once immobilized on the collagen matrix. Two types of collagen were used, one produced by the United States Department of Agriculture and the other produced by FMC. The USDA collagen contained unhydrolyzed telepeptide linkages and required pretreatment to reduce collagenaselike activity of the enzyme. Activity analysis of the immobilized enzyme complex showed that membranes with enzyme loading less than 10 mg enzyme/g of wet membrane in the reactor were dimensionally stable. The degree of crosslinking was an important parameter. Membranes with structural opening up to three times the initial dry thickness were found to be the maximum limit for controlled release of enzyme from the collagen membrane during enzymatic reaction. Higher activities and better stability of the enzyme in collagen membrane were found for covalent crosslinking of the enzyme to treated collagen films. The hydrolysis of soybean vegetable protein with the immobilized enzyme in a recycle reactor at enzyme loading of mg/g of wet membrane at 40°C, pH 3.4, produced 56.5% of soluble protein in 10h. The production is equivalent to 1.84 h total contact time between the substrate and the immobilized enzyme. The average productivity based on a stable enzyme activity and 20g of dry membrane was 329 mg of protein/g/mg of active enzyme immobilized. The productivity of the free enzyme in a batch reactor was 62.5 mg protein/h/mg enzyme.
Production of anchorage‐dependent cells—problems and their possible solutions
Authors: Jensen Mona D. 
Published: December 2004

AbstractIn vitro cell culture has proven to be a valuable procedure for the study of cellular function as well as the production of veterinary and human vaccines. In recent years, interest in cell culture technology has grown due to the need for production of interferon, monoclonal antibodies, various hormones, and other cell‐secreted products with potential medical uses. Many of these products have been successfully produced only be cells which require attachment to a surface in order to grow and function. This requirement places severe limitations on the economics and feasibility of large‐scale culture. In response, a number of new technologies have been proposed and developed in attempts to increase the surface area available within a given culture volume, to increase the cell density per surface area, to decrease medium and serum requirements per unit of product, to increase product production by control of the cellular environment, and to automate the production process. Some of the techniques and described along with their ability to control the environment of cells in culture.
A mathematical model of growth and alkaloid production in the submerged culture of Claviceps purpurea
Authors: Pažoutová Sylvie , Votruba Jaroslav , Řeháček Zdeněk 
Published: December 2004

AbstractA mathematical model of the batch cultivation of Claviceps purpurea was formulated. The main attention was devoted to the effect of exocellular and intracellular phosphate on the growth of the mycelium and production of clavine alkaloid under experimental conditions without limitation by carbon and nitrogen sources. The method of nonlinear regression was used ot predict the optional technological regime of the phosphate addition in the batch culture at different time intervals of additions.
Fluid flow pattern in upflow reactors for anaerobic treatment of beet sugar factory wastewater
Authors: Heertjes P. M. , Kujivenhoven L. I , van der Meer R. R. 
Published: December 2004

AbstractResidence‐time‐distribution experiments for the fluid in a 30‐m3 pilot plant and a 200‐m3 prototype upflow reactor were performed by means of continuous injection of an LiCl solution as a tracer in the influent of the reactor and measurement of the response of this stimulus on several location in the reactor and in the effluent. In a similar way as described in an article published earlier, models have been developed by use of the measured data of the fluid flow pattern which consisted of region of ideal mixing, plug flow, dead space, and short circuiting. It appeared that the fluid flow patterns in the two reactors were to a large extent analogous. For the pilot plant, three‐mixer models appeared to be appropriate while for the prototype reactor two‐mixer models have been found. This differences was a result of the difference in the heights of the sludge beds in the reactors: 2–3 m in the pilot plant and only 0.4 m in the prototype reactor, a result of too small an amount of sludge. Another differences was that, due to large amount of mud in the prototype reactor, a region of dead space occurred in the models for the fluid flow pattern in this reactor. The dimension of the prototype reactor have been chosen according to several recommendations obtained from work with the pilot plant (e.g., scale‐up should be done by increasing the cross section of the reactor; one influent point should be applied per 5 m2 bottom surface). The results presented here clearly show the value of these recommendations.
Statistical mechanical estimation of the free energy of formation of E. coli biomass for use with macroscopic bioreactor balances
Authors: Grosz Ron , Stephanopoulos Gregory 
Published: December 2004

AbstractThe need for the determination of the free energy of formation of biomass in bioreactor second law balances is well established. A statistical mechanical method for the calculation of the free energy of formation of E. coli biomass is introduced. In this method, biomass is modelled to consist of a system of biopolymer networks. The partition function of this system is proposed to consist of acoustic and optical modes of vibration. Acoustic modes are described by Tarasov's model, the parameters of which are evaluated with the aid of low‐temperature calorimetric data for the crystalline protein bovine chymotrypsinogen A. The optical modes are described by considering the low‐temperature thermodynamic properties of biological monomer crystals such as amino acid crystals. Upper and lower bounds are placed on the entropy to establish the maximum error associated with the statistical method. The upper bound is determined by endowing the monomers in biomass with ideal gas properties. The lower bound is obtained by limiting the monomers to complete immobility. On this basis, the free energy of formation is fixed to within 10%. Proposals are made with regard to experimental verification of the calculated value and extension of the calculation to other types of biomass.
Kinetics of growth of the hydrogen‐oxidizing bacterium Alcaligenes eutrophus (ATCC 17707) in chemostat culture
Authors: Siegel Robert S. , Ollis David F. 
Published: December 2004

AbstractThe hydrogen‐oxidizing bacterium, Alcaligenes eutrophus (ATCC 17707), was grown in chemostat culture with gas‐phase (hydrogen, oxygen, and carbon dioxide) and liquid‐phase (mineral nutrients) feedstreams; data were used to generate an analytical form for the specific growth rate equation. Model parameters obtained include Monod rate parameters for dissolved hydrogen and oxygen gases, yield coefficients, and specific maintenance rates under conditions of hydrogen or oxygen limitations. These values are similar to some obtained previously by Ohi et al. for another hydrogen bacterium. The observed increase in specific maintenance rates under hydrogen‐versus‐oxygen‐limited culture may be associated with hydrogenase deactivation by oxygen.
Studies on on‐line bioreactor identification. II. Numerical and experimental results
Authors: San Ka‐Yiu , Stephanopoulos Gregory 
Published: December 2004

AbstractThe on‐line bioreactor identification methodology of the preceding article (Part I) was tested with a series of numerical simulations and laboratory experiments. Results of these studies presented herein confirm the superior characteristics of the proposed estimator and its applicability to modelling studies, or on‐line bioreactor control. The sensitivity of the estimation scheme with respect to the respiratory quotient measurement is discussed, and suggestions to bypass these problems are offered.
Fermentation equations for propionic‐acid bacteria and production of assorted oxychemicals from various sugars
Authors: Papoutsakis Eleftherios Terry , Meyer Charles L. 
Published: December 2004

AbstractFermentation (stoichiometric) equations are derived for anaerobic fermentations of propionic‐acid bacteria (of both the Propionibacterium and acrylate pathways) and for production of various oxychemicals (butanol, acetone, isopropanol, butanediol, butyrate, acetate, propionate, succinate, lactate, and acrylate) from pentoses, hexoses, and cellobiose. The derivations of the equations are based on the fermentation biochemistries of the various bacterial classes. The validity of the equations is tested using fermentation data from the literature. The equations are shown to be valuable, among other uses, for calculating maximal yields and selectivities of the various fermentation products, as “gateway sensors” for monitoring of the fermentations, and for calculating the extents of the various intracellular reactions of the fermentation biochemistry.
High algal production rates achieved in a shallow outdoor flume
Authors: Laws E. A. , Taguchi S. , Hirata J. , Pang L. 
Published: December 2004

AbstractA mass culture of Tetraselmis suecica grown in seawater enriched with only inorganic nutrients and CO2 in a shallow outdoor flume containing foil arrays to effect systematic vertical mixing achieved average daily production rates of over 40 g ash‐free dry wt (AFDW)/m2 over periods as long as one month when grown on a three‐day dilution cycle. Photosynthetic efficiencies associated with these high production rates averaged 8–11% based on visible irradiance. Operation of the system in a one‐, two‐, or four‐day dilution cycle resulted in lower photosynthetic efficiencies of 6–7%. A remarkable feature of the three‐day dilution cycle results was the fact that production on the third day after dilution averaged 60–70 g AFDW/m2, and corresponding photosynthetic efficiencies averaged 13–19%. The high production rates and photosynthetic efficiencies achieved on the third day after dilution may have reflected the nonequilibrium nature of the production cycle and, in particular, the fact that the adaptation of the cells to changing light condition lagged behind light condition in the culture.
Continuous cultivation of recombinant Escherichia coli: Existence of an optimum dilution rate for maximum plasmid and gene product concentration
Authors: Seo Jin‐Ho , Bailey James E. 
Published: December 2004

AbstractGrowth yield factors, plasmid stability, cellular plasmid content, and cloned gene product activity for Escherichia coli HB101 containing plasmid pDM246 were measured at several dilution rates in continuous culture. Cell mass yield per mass of glucose consumed declined with increasing dilution rate. There was no evidence of plasmid segregational instability in any experiments, none of which employed selective medium. Plasmid content per cell varied with population‐specific growth rate as observed in earlier batch experiments with the same strain. Plasmid content declined with increasing specific growth rate following indication of a maximum number of plasmids per cell at specific growth rates of ca. 0.3 h−1. Cloned gene product (β‐lactamase) activity exhibited a sharp maximum with respect to dilution rate in continuous culture. Qualitatively different results were observed in previous experiments in batch cultivation in which specific growth rate changes were effected by altering medium composition.
Growth dynamics of a methylotroph (Methylomonas L3) in continuous cultures. II. Growth inhibition and comparison against an unstructured model
Authors: Chu I‐Ming , Papoutsakis Eleftherios Terry 
Published: December 2004

AbstractHigh methanol concentrations have a negative effect on the growth rate and the biomass yield of growth transients induced by methanol pulses in continuous cultures of Methylomonas L3. The physiological basis of this effect is investigated by measuring the effect of the methanol pulse on the cell energy charge (EC) and ATP, ADP, and AMP concentrations, and by comparing the results of the pulse transients against an unstructured model. The methanol pulse is shown to lead to increased values of the cell EC and ATP concentration, and thus, inhibition and reduced availability of biosynthetic energy are excluded as causes of inhibition. When the biomass and methanol profiles of the transient experiments are compared in phase‐plane diagrams against computer simulations based on the model, satisfactory agreement between experimental data and model predictions is found in single‐substrate, high‐dilution‐rate experiments. Conversely, poor agreement between experimental data and simulation results indicates a more severe growth inhibition than the model predicts at low dilution rates and a less severe one in mixed‐substrate experiments. Based on these findings and other relevant physiological information, we propose that the large variations in the negative effect of methanol on growth result from the fact that cells accumulate methanol to widely different concentrations depending on their physiological state. In their effort to detoxify from the high intracellular methanol and formaldehyde concentrations, cells oxidize considerably more methanol than they can incorporate into biomass. This leads to a useless ATP surplus, which the cells must hydrolyze without doing any useful biosynthetic work, and this results in lower biomass yields.
Computer control of carbon–nitrogen ratio in Spirulina platensis
Authors: Walach Marek R. , Bazin Michael J. , Pirt S. John , Balyuzi Hushang H. M. 
Published: December 2004

AbstractAn on‐line computer was used to control the ratio of carbon to nitrogen in algal biomass. An indirect method of growth and biomass estimation was utilized. This was based on balancing the amount of CO2 carbon in and out of the algal bioreactor. It was shown that growth conditions govern the morphology and composition of Spirulina platensis. Cells grown under light limitation were narrower, had high levels of phycocyanin pigments, and were packed full of small lipid granules. Whereas cells grown under nitrogen limitation lost their characteristic blue‐green color, had reduced levels of phycocyanin, were fatter, and were packed full of larger lipid granules.
Control of an ethanol fermentation carried out with alginate entrapped Saccharomyces cerevisiae
Authors: Mandenius C. F. , Mattiasson B. , Axelsson J. P. , Hagander P. 
Published: December 2004

AbstractProcess control of different reactor models for continuous production of ethanol from sucrose with immobilized yeast has been studied. An enzyme thermistor with immobilized invertase recorded the concentration of sucrose continuously. Ethanol was recorded by a membrane gas sensor with a SnO2 semiconductor used as detector. A process computer controlled the substrate feed to keep substrate as well as ethanol concentration at preset values by using algorithms of varying complexity. It was thereby demonstrated that PID regulators as well as more advanced algorithms (Otto–Smith regulator, state feedback from a Kalman filter, and cascade control) are useful alternatives to maintain a constant concentration in the fermentor effluents. The time required for the system to return to predetermined conditions after various kinds of disturbances has been especially studied. It was shown that the more advanced regulator used the shorter time.
Lipase reaction in AOT‐isooctane reversed micelles: Effect of water on equilibria
Authors: Han Daeseok , Rhee Joon Shick , Lee Sun Bok 
Published: December 2004

AbstractThe effect of water on equilibria for hydrolytic reaction in reversed micelles has been investigated using lipase as a model enzyme. The effect of water on equilibria has been ignored for hydrolase reactions in an aqueous phase. In a reversed micellar system, however, the equilibrium of the lipase reaction was changed when water was added during the hydrolytic reaction. Furthermore, equilibrium fractional conversion is affected by the initial water concentration, being shifted to higher values with higher water concentrations, with other reaction conditions being held constant, indicating that the reaction should be regarded as a two‐substrate process. Equations corresponding to a two‐substrate, second‐order reversible model are derived and used for further analysis. The progress curves predicted from the rate equations agree very well with the experimental results under various reaction conditions. The values of the molar ratio of water to surfactant (R) which maximize the initial reaction rate and maximum fractional conversion is predictable from the derived rate equations and the resulting relationship between R and the kinetic constants.
Novel cationic triazine dyes for protein purification
Authors: Clonis Y. D. , Stead C. V. , Lowe C. R. 
Published: December 2004

AbstractThe effectiveness of a new immobilized cationic triazine dye was investigated alongside two new amphoteric triazine dyes and two well known anionic triazine dyes, Procion Red H‐3B and Procion Blue H‐B, as chromatographic media for binding four familiar proteases–trypsin, chymotrypsin, thrombin and carboxypeptidase‐B–as well as a typical oxidoreductase, lactate dehydrogenase, and human serum albumin. The new affinity adsorbent, CL‐Sepharose‐immobilized Cationic Dye, specifically binds trypsin‐like proteases such as trypsin, thrombin, and carboxypeptidase‐B, but none of the other proteins tested. In contrast, the amphoteric and anionic immobilized dyes bind all the other proteins tested in a similar fashion. The specificity of the cationic dye was exploited in the resolution of trypsin and chymotrypsin from a crude activated bovine pancreatic extract. The procedure described here affords trypsin with specific activity of 7400 units/mg with a 79% overall yield in a single step. The immobilized cationic dye, unlike previously reported adsorbents for trypsin, is inexpensive, readily synthesized, and displays a workable capacity of 4000 trypsin units or 0.55 mg protein/g moist weight gel (1.2 μmol dye/g moist weight gel) from a crude bovine pancreatic extract and, thus, is potentially amenable to process‐scale operations.
Conversion of α‐ketoglutarate into L‐glutamic acid with urea as ammonium source using multienzyme systems and dextran‐NAD+ immobilized by microencapsulation within artificial cells in a bioreactor
Authors: Gu Kang Fu , Chang Thomas Ming Swi 
Published: December 2004

AbstractUrea could be effectively converted into L‐glutamic acid with semipermeable nylon‐polyethylenimine artificial cells containing L‐glutamic dehydrogenase (EC 1.4.1. 3), yeast alcohol dehydrogenase (EC 1.1.1.1), urease (EC 3.5.1. 5) and soluble dextran‐NAD+. For batch conversion, the artificial cell suspension to total reaction volume ratios ranged from 1 in 5 to 1 in 60. From 22.6 to 53.4 μmol of L‐glutamic acid could be produced by 0.4 mL artificial cell suspension within 2 h. The corresponding conversion ratios were 56.5‐11. 1%. The L‐glutamic dehydrogenase multienzyme system showed a good storage stability: 66.0% of the original activity was retained after 1 month of storage at 4°C. A small bioreactor was prepared to contain 4.0 mL artificial cells. At a flow rate of SV = 1.5 h−1, the maximum conversion rate was 49.6 μmol L‐glutamic acid/p h. Thirty‐eight percent of the maximum activity was retained when continuously used for four days at 22°C. A kinetic analysis for the L‐glutamic dehydrogenase multienzyme system was studied. The Michaelis constants are as follows: α‐ketoglutarate is 0.838 mM; urea is 1.90 mM; dextran‐ NAD+ is 0.345 mM; and ethanol is 5.31 mM.
Surface immobilization of plant cells
Authors: Archambault J. , Volesky B. , Kurz W. G. W. 
Published: December 2004

AbstractA novel technique has been developed to immobilize plant cells. The cells are deposited on a surface of manmade fibrous material that provides for strong binding of the plant tissue biomass growing in the submerged culture. The immobilized plant cells remain fully viable. Relatively uniform biomass loadings of up to 20 mg d.w. plant cells/cm2 support material have been attained. All plant cells from the inoculum suspension became attached within the first 24–48 h depending on the support matrix configuration and hydraulic culture conditions. The advantages and scale‐up potential of this technique are discussed and compared to other culturing modes.
A simple, leaky cell growth model for plant cell aggregates
Authors: Frazier George C. 
Published: December 2004

AbstractA simple growth model is proposed for plant cell aggregates which accounts for leakage of a single intermediate metabolite from the aggregates to the medium. This model predicts a lag phase in the growth curve whose extent is determined by the intermediate metabolite leakage coefficient and its equilibrium distribution coefficient between the medium and the cell aggregates, the size of the inoculum relative to the system total water content, and the initial intermediate metabolite content in the medium. The model thus provides for an interaction between growing plant cells and their environment in a way that has heretofore been unquantified. Preliminary validation of the model has been made against literature data of Dioscorea deltoidea grown in batch suspension cell culture on sucrose, yielding a correlation coefficient of 0.997. The predicted glucose + fructose concentration in the medium agrees reasonably well with experimental measurements after ca, 3.5 days of culture, although a discrepancy exists between model prediction and experiment immediately after startup. Further validation of the model is suggested on this and other plant species.