bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cultivation of Thalictrum rugosum cell suspension in an improved airlift bioreactor: Stimulatory effect of carbon dioxide and ethylene on alkaloid production
Authors: Kim Dong‐II , Pedersen Henrik , Chin Chee‐Kok 
Published: December 2004

AbstractAirlift bioreactor operations have been studied for the growth‐associated production of secondary metabolites from plant cell suspension cultures. The model system used in this work was Thalictrum rugosum producing berberine, an isoquinoline alkaloid. The airlift system was well suited for growth of Thalictrum cell suspension cultures unless the cell density was high. At high cell density, the airlift system with a draught tube was not adequate due to large aggregates clogging the recirculation paths. This was overcome by use of a cell scraper in the reactor. For berberine production, gas‐stripping also played a significant role and it was discovered that CO2 and ethylene were important for product formation. By supplying a mixture of CO2 and ethylene into the airlift system, the specific berberine content was increased twofold. It is evident that continuous gas sparging was harmful for the production of berberine without supplementation with other gases.
Modeling linear and variable growth in phosphate limited suspension cultures of Opium poppy
Authors: Curtis Wayne R. , Hasegawa Paul M. , Emery Alden H. 
Published: December 2004

AbstractIn examining the growth kinetics of cell suspensions of opium poppy (Papaver somniferum), the increase in biomass with time was observed to be linear over the entire batch growth period of up to 20 days. Although batch growth profiles were reproducible utilizing the same inoculum, growth rates varied tremendously when experiments were inoculated with cells from different flasks. Both of these phenomena are difficult to explain with conventional batch growth models. In a series of a experiments, phosphate was determined to be the growth‐rate‐limiting substrate. By expressing growth rate in terms of the intracellular reserves of phosphorus, a growth model which expresses kinetics in terms of the intracellular phosphorus contents of the cells is shown to predict both linear growth character and inoculum dependent variability in growth. The stationary phase phosphate content of seven plant suspension cultures of different plant species was found to be comparable to phosphorus levels of phosphate‐starved poppy cells, which suggests that phosphate limitation may be common for plant tissue culture. The applicability of this model to other biological systems which display similar batch growth patterns when subjected to inorganic nutrient deprivation is discussed.
Continuous acetone‐butanol‐ethanol (ABE) fermentation using immobilized cells of Clostridium acetobutylicum in a packed bed reactor and integration with product removal by pervaporation
Authors: Friedl Anton , Qureshi N. , Maddox Ian S. 
Published: December 2004

AbstractAn integrated solvent (ABE) fermentation and product removal process was investigated. A stable solvent productivity of 3.5 g/L h was achieved by using cells of Clostridium acetobutylicum immobilized onto a packed bed of bonechar, coupled with continuous product removal by pervaporation. Using a concentrated feed solution containing lactose at 130g/L, a lactose value of 97.9% was observed. The integrated fermentation and product removal system, with recycling of the treated fermentor effluent containing only low amount of solvents (/but lactose and acids), leads to only low acid losses. Therefore, most of the acids are converted to solvents, and this results in a high solvent yield of 0.39 g solvents/g lactose utilized. The pervaporation system provided a high product removal rate even at low solvent concentrations. A solvent membrane flux of 7.1 g/m2 h with a selectivity of 5 was achieved during these investigations. The system proved to be very reliable.
Propionic acid fermentation of lactose by Propionibacterium acidipropionici: Effects of pH
Authors: Hsu Sheng‐Tsiung , Yang Shang‐Tian 
Published: December 2004

AbstractBatch propionic acid fermentation of lactose by Propionibacterium acidipropionici were studied at various pH values ranging from 4.5 to 7.12. The optimum pH range for cell growth was between 6.0 and 7.1, where the specific growth rate was ∼0.23 h−1. The specific growth rate decreased with the pH in the acids have been identified as the two major fermentation products from lactose. The production of propionic acid was both growth and nongrowth associated, while acetic acid formation was closely associated with cell growth. The propionic acid yield increased with decreasing pH; It changed from ∼33% (w/w) at pH 6.1–7.1 to ∼63% at pH 4.5–5.0. In contrast, the acetic acid yield was not significantly affected by the pH; it remained within the range of 9%–12% at all pH values. Significant amounts of succinic and pyruvic acids were also formed during propionic acid fermentation of lactose. However, pyruvic acid was reconsumed and disappeared toward the end of the fermentation. The succinic acid yield generally decreased with the pH, from a high value of 17% at pH 7.0 to a low 8% at pH 5.0 Effects of growth nutrients present in yeast ex‐tract on the fermentation were also studied. In general, the same trend of pH effects was found for fermentations with media containing 5 to 10 g/L yeast extract. However, More growth nutrients would be required for fermentations to be carried out efficienytly at acidic pH levels.
Effect of light irradiation on anthocyanin production by suspended culture of Perilla frutescens
Authors: Zhong Jian‐jiang , Seki Tatsuji , Kinoshita Shin‐ichi , Yoshida Toshiomi 
Published: December 2004

AbstractAfter a series of experiments on photoperiodicity and light intensity under daylight supplied by an ordinary fluorescent lamp in cultivations using a flask and a roux bottle, it was found that irradiation at 27.2 W/m2 for the whole period was effective for anthocyanin production by a suspended culture of Perilla frutescens (shiso). A high amount of anthocyanin pigments, 3.0 g/L, was obtained in a bubble column bioreactor after 10 days of cultivation at an aeration rate of 0.1 vvm with light irradiation at 27.2 W/m2, while 2 g/L was obtained at 13.6 W/m2 and very little at 54.4 W/m2. A high amount of anthocyanin pigments, 2.9 g/L, was also produced using an aerated and agitated bioreactor at an agitation speed of 130 rpm, an aeration rate of 0.1 vvm and light irradiation intensity of 27.2 W/m2. The amount of anthocyanin produced was more than twice that without light irradiation, Keeping the other cultivation conditions the same. The results obtained also showed that the amount of anthocyanin pigment accumulated in a shake flask could be rather well reproduced in bioreactors for both aerated culture, and aerated and agitated culture, by improving the conditions of light irradiation, which conspicuously affects metabolite formation.
Development of a kinetic model for the alcoholic fermentation of must
Authors: Caro I. , Pérez L. , Cantero D. 
Published: December 2004

AbstractWe Propose a kinetic expression which accounts for the temperature dependence of ethanol yield losses in batch alcoholic fermentation. Moreover, the characteristic parameters of the microbial growth equation have been calculated for Saccharomyces cerevisiae under typical wine industry conditions. A substrate consumption equation is established which minimizes possible model deviations in the latter process stages. Experimental data were obtained in the laboratory and the proposed equations were then applied at an industrial level (2.5 × 104 L) where they described the data well.
The effect of electrochemical regeneration upon the enzymatic catalysis of a thermodynamically unfavorable reaction
Authors: Laval Jean Marc , Moiroux Jacques , Bourdillon Christan 
Published: December 2004

AbstractThe association between enzymatic and electrochemical reactions, enzymatic electrocatalysis, had proven to be a very powerful tooth in both analytical and synthetic fields. However, most of the combinations studied have involved enzymatic catalysis of irreversible or quasi‐irreversible reaction. In the present work, we have investigated the possibility of applying enzymatic electrocatalysis to a case where the electrochemical reaction drives a thermodynamically unfavorable reversible reaction. Such thermodynamically unfavorable reactions include most of the oxidations catalyzed by dehydrogenases. Yeast alcohol dehydrogenase (E.C. 1.1.1.1) was chosen as a model enzyme because the oxidation of ethanol is thermodynamically very unfavorable and because its kinetics are well known. The electrochemical reaction was the oxidation of NADH which is particularly attractive as a method of cofactor regeneration. Both the electrochemical and enzymatic reactions occur in the same batch reactor in such a way that electrical energy is the only external driving force. Two cases were experimentally and theoretically developed with the enzyme either in solution or immobilized onto the electrode's surface. In both cases, the electrochemical reaction could drive the enzymatic reaction by NADH consumption in solution or directly in the enzyme's microenvironment. However even for a high efficiency of NADH consumption, the rate of enzymatic catalysis was limited by product (acetaldedehyde) inhibition. Extending this observation to the subject of organic synthesis catalyzed by dehydrogenases, we concluded that thermodynamically unfavorable reaction and can only be used in a process if efficient NAD regeneration and product elimination are simultaneously carried out within the reactor.
Implementation of an adaptive controller for the startup and steady‐state running of a biomethanation process operated in the CSTR mode
Authors: Renard P. , Van Breusegem V. , Nguyen M.‐T. , Naveau H. , Nyns E.‐J. 
Published: December 2004

AbstractAn adaptive control algorithm has been implemented on a biomethanation process to maintain propionate concentration, a stable variable, at a given low value, by steering the dilution rate. It was thereby expected to ensure the stability of the process during the startup and during steady‐state running with an acceptable performance. The methane pilot reactor was operated in the completely mixed, once‐through mode and computer‐controlled during 161 days. The results yielded the real‐life validation of the adaptive control algorithm, and documented the stability and acceptable performance expected.
Reaction kinetics in biofilms
Authors: Lewandowski Zbigniw , Walser Gabriele , Characklis William G. 
Published: December 2004

AbstractA novel in situ microtechnique allows evaluating parameters of diffusion‐controlled reactions in biofilms. A microprobe, 15 μm in diameter, was used to simultaneously measure the dissolved oxygen concentration and the optical density at different depths in a submerged biofilm. Based on the results, the biofilm diffusion coefficient for dissolved oxygen, Df the dissolved oxygen flux through the biofilm surface, J02, and the half velocity coefficient, Ks, have been calculated.
Effect of photobioreactor inclination on the biomass productivity of an outdoor algal culture
Authors: Lee Yuan‐Kun , Low Chin‐Seng 
Published: December 2004

AbstractThe profiles of photon flux density incidented on a tubularloop photobioreactor in the day could be altered by inclining the bioreactor at an angle with the horizontal. The photon flux density at noon decreased with increasing angle of inclination, whereas the photon flux density in the early morning and late afternoon increased with increasing angle of inclination. The overall photosynthetic radiance received by the bioreactor inclined at 0, 25, 45, and 80° was 1:0.89:0.77:0.62. Regardless of the angle of bioreactor inclination, the overall biomass output rate of a fed‐batch culture over an 8‐h/day period was comparable (26–36 g‐biomass m−2 bioreactor surface area day−1). As a bioreactor inclined at an angle occupied smaller land area, and daily biomass output rate per land area of a bioreactor inclined at 80° (130 g‐biomass m−2 land) was about six times of that obtainable at horizontal position (21‐g biomass m−2 land). The bioenergetics growth yield from the absorbed photosynthetic radiance was not a constant but an inverse function of the photon flux density. The quasi‐steady state chlorophyll content of the Chlorella cells varied between 36 and 63 mg g−1 cells. Photoinhibition of the maximum photosynthetic capacity was not observed in this study.
Interaction of invertase with polyelectrolytes
Authors: Dautzenberg Herbert , Kötz Joachim , Philipp Burkart , Rother Gudrun , Schellenberger Alfred , Mansfeld Johanna 
Published: December 2004

AbstractIn connection with our work on polyelectrolyte complex formation with polyampholytes, the interaction between invertase and several linear polyelectorlytes has been investigated by means of turbidimetry, light scattering measurements, and determination of the enzyme activity. Polyelectrolyte complex formation of invertase was shown to occur with cationic polyelectrolytes only. The light‐scattering data yield information on aggregation and desegregation processes in complex formation. As indicated by our results, only a part of the protein molecules is engaged in this Coulombic interaction, and this part shows a rather small enzyme activity only. Thus, a direct interaction between invertase and a cationic polyelectrolyte is no effective approach to enzyme binding, but a complete immobilization of invertase can be achieved via an “inclusion flocculation” with a symplex formed by interaction between an anionic and a cationic linear polyelectrolyte or via immobilization in symplex microcapsules.
Measurement and simulation of the morphological development of filamentous microorganisms
Authors: Yang H. , Reichl U. , King R. , Gilles E. D. 
Published: December 2004

AbstractGrowth of Streptomyces tendae was investigated in submerged culture. Images of several mycelia were analyzed by means of an image‐processing system. The studies revealed that tip growth angles and branching outgrowth angles could be regarded as normally distributed. Based on these results, a random model for directional growth of hyphal tips as well as directional growth of branches is proposed. This model shows curved elongation of hyphal tips, so that the morphological development of a mycelium up to the formation of a pellet is predicted, similar to that observed in nature.
Agitation induced cell injury in microcarrier cultures. Protective effect of viscosity is agitation intensity dependent: Experiments and modeling
Authors: Lakhotia Sanjay , Papoutsakis Eleftherios T. 
Published: December 2004

AbstractThe effect of medium viscosity on the specific death rate of bovine embryonic kidney (BEK) cells cultured in spinner flask microcarrier cultures has been examined for various impeller speeds. Two types of media were used, a serum‐containing growth medium and a serum‐free maintenance medium. The latter does not support cell growth. We found that increasing medium viscosity suppresses cell death rates in both growth and maintenance medium cultures in an agitation‐intensity‐dependent fashion; the beneficial effect of medium viscosity in reducing the specific death rate is amplified as the agitation rate is increased. Furthermore, increasing medium viscosity has no effect on the specific death rate of the cells when the agitation rate is below a critical level. A model based on the turbulent energy content of eddies in the dissipation spectrum of turbulence of length scales on the order of magnitude of the microcarrier diameter and lower has been developed to account for cell death due to both bead‐to‐bead and bead‐to‐eddy interactions. The model constitutes a significant departure from previous efforts first because both types of interactions are accounted for simultaneously and second because the properties of a spectrum of eddies instead of the Kolmogorov‐scale eddy size alone are used in the model. The model explains the functional dependence of the specific death rates on the medium viscosity at varying agitation intensities.
Displacement of equilibrium in electroenzymatic reactor for acetaldehyde production using yeast alcohol dehydrogenase
Authors: Lortie Robert , Fassouane Aziz , Laval Jean‐Marc , Bourdillon Christian 
Published: December 2004

AbstractElectrochemical regeneration of NAD was performed in a bench scale reactor in which yeast alcohol dehydrogenase catalyzed the oxidation of ethanol. By recycling one of the products of the reaction, it was possible to displace the equilibrium and favor the production of acetaldehyde. The flow‐through electrode was made of graphite felt and had a specific area of 275 cm−1. A mathematical model taking into account the enzymatic and electrochemical reaction rates as well as the mass transfer to the electrode was used to analyze the results. The limiting steps in the reactor are the electrochemical reaction for low potentials and the cofactor mass transfer for high potentials.
Effects of electroconductive heat treatment and electrical pretreatment on thermal death kinetics of selected microorganisms
Authors: Palaniappan Sevugan , Sastry Sudhir K. , Richter Edward R. 
Published: December 2004

AbstractSuspensions of yeast cell (zygo Saccharomyces bailii) in a phosphate buffer solution were subjected to conventional (hot water) and ohmic (electric current) heating under identical temperature histories. Experiments were also conducted with cells of Escherichia coli to compare the lethal effect of combination of sublethal electrical preteatment and conventional heating with conventional heating. The kinetic parameters (D,Z,K and Ea) were determined for both organisms during different treatments. There was no significant difference in the death rate of yeast cells during conventional and ohmic heating at the voltage range used in this study. Results of electrical pretreatment and conventional heating on E. coli indicated differences under certain conditions when compared with pure conventional heating. Thus it is concluded that microbial death during ohmic heating was due primarily to thermal effects with no significant effect of electric current per se. Sublethal electrical pretreatment appears to offer potential for increased bacterial inactivation in certain cases.
Kinetics of lipase‐catalyzed esterification in supercritical CO2
Authors: Marty A. , Chulalaksananukul W. , Willemot R. M. , Condoret J. S. 
Published: December 2004

AbstractThis study compares two solvents for enzymatic reactions: supercritical carbon dioxide (SCCO2) and organic solvent (n‐hexane). The model reaction that was chosen was the esterification of oleic acid by ethanol catalyzed by an immobilized lipase fromMucor miehei(Lypozyme). The stability of the enzyme appeared to be quite good and similar in both media but was affected by the water content. Partition of water between solvents and immobilized enzyme has been calculated from experimental adsorption isotherms. The water content of the solid phase has a dramatic influence on the activity of the enzyme and its optimum value for activity was about 10% (w/w) in both media. A kinetic study enabled a Ping‐Pong Bi‐Bi reaction mechanism with inhibition by ethanol to be suggested. Despite some differences in kinetic constants, activity was in the same range in both media. Hypotheses for explaining the kinetic constant variations have been proposed and particular attention has been paid to the pH effects.
Study of population dynamic for a recombinant bacterium during continuous cultures: Appliction of data filtering and smoothing
Authors: Nancib Nabil , Mosrati Ridha , Boudrant Joseph 
Published: December 2004

AbstractA numerical method to process experimental data concerning plasmid stability of a recombinant bacteria during continuous cultures with nonselective media is proposed here. This method differs from previous ones in that it uses the derivatve form of the state equation of the Imanaka‐Aiba model for recombinant cultures. The methodology proposed here allows one to estimate values for the two model parameters without forcing them to be constant. Until now, this could not be done using classical analytical techniques because these parameters have been considered invariable because of the integration used in the evaluation of the model. These parameters are (1) the difference in the specific growth rates between plasmid‐carrying cells and plasmid‐free cells (δμ), and (2) the probability of plasmid loss by plasmid‐containing cells (ρr μ+). The derivative technique used here is completed by mathematical treatments involving data filtering and smoothing. The values of the two parameters are in agreement with those already publised. The current technique does not impose preconditions and permit us to further study related phenomena.
Modeling the population dynamics of baculovirus‐infected insect cells: Optimizing infection strategies for enhanced recombinant protein yields
Authors: Licari P. , Bailey J. E. 
Published: December 2004

AbstractThe insect cell‐baculovirus model presented here is capable of simulating cell population dynamics, extracellular virion densities, and heterologous product titers in reasonable agreement with experimental data for a wide rang of multiplicities of infection (MOI) and times of infection. The model accounts for the infection of a single cell by multiple virions and the consequences on the time course of infection. The probability of infection by more than one virion was approximated using the Poisson distribution, which proved to be a refinement over second‐order kinetics. The model tracks initiation and duration of important events in the progression of infected cell development (virus replication, recombinant protein synthesis, and cell lysis) for subpopulations delineated by the time and extent of their initial infection. The model suggests infection strategies, weighing the importance of MOI and infection time. Maximum product titers result from infection in the early exponential growth phase with low MOI.
New approach for selective separation of dilute products from simulated clostridial fermentation broths using cyclodextrins
Authors: Shity Halla , Bar Raphael 
Published: December 2004

AbstractThe ability of cyclodextrins (CD) to form crystalline insoluble complexes with organics was explored in this study in view of a selective separation of dilute products obtainable from three clostridial fermentation systems. To this purpose, a product or a product mixture at a concentration of 0.150 mM each were treated with α‐CD or β‐CD (0.150 mM) in aqueous solutions as well as in a nutrient broth as a simulated fermentation medium. In the acetone‐butanol‐ethanol system, and in the butanol‐iso‐propanol system, α‐CD was found to precipitate selectively 48% and 46% butanol after 1 h agitation at 30°C. However, β‐CD was found to be superior for the butyric acid‐acetic acid system because it selectively precipitated 100% butyric acid under the same conditions. Cooling the three product system with α‐CD to 4°C for 24 h increased significantly the crop of precipitates but decreased the selectivity for either butanol or butyric acid. Cyclodextrins were thus shown to offer potentially a new exciting possibility for downstream processing of low‐concentration fermentation products.
Gas phase transesterification reactions catalyzed by lipolytic enzymes
Authors: Parvaresh Firooze , Robert Hervé , Thomas Daniel , Legoy Marie‐Dominique 
Published: December 2004

AbstractPorcine pancreatic lipase and Fusarium solani cutinase were used to catalyze transesterification reactions between methyl propionate, ethyl propionate, and a series of primary alcohols at high temperatures in a continuous packed‐bed gas‐solid reactor, in which the solid phase is composed of the enzyme and the substrates and products are in a gaseous form. In this type of system, enzyme activity was found to depend essentially on the water activity (Aw) of the enzyme preparation.