bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved taxol yield by aromatic carboxylic acid and amino acid feeding to cell cultures of taxus cuspidata
Authors: Fett‐Neto Arthur G. , Melanson Stewart J. , Nicholson Sherwin A. , Pennington Jason J. , DiCosmo Frank 
Published: December 2004

AbstractCell culture of Taxus cuspidata represents an alternative to whole plant extraction as a source of taxol and related taxanes. Feeding phenylalanine to callus cultures was previously shown to result in increased taxol yields, probably due to the involvement of this amino acid as a precursor for the N‐benzoylphenylisoserine side chain of taxol. Inthis study, we have examined the effect of various concentrations of phenylalanine, benzoic acid, N‐benzoylglycine, serine, glycine, alanine, and 3‐amino‐3‐phenyl‐propionic acid on taxol accumulation in 2‐year‐old cell suspensions of Taxus cuspidata, cell line FCL1F, and in developing callus cultures of T. cuspidata. All compounds tested were included in media at stationary phase (suspensions) or after the period of fastest growth (calli). Alanine and 3‐amino‐3‐phenyl‐propionicacid were tested only in callus cultures and did not affect taxol accumulation. Significant increases or trends toward increases in taxol accumulationin callus and suspensions were observed in the presence of phenylalanine, benzoic acid, N‐benzoylglycine, serine, and glycine. The greatest increases in taxol accumulation were observed in the presence of various concentrations of phenylalanine (1 mM for callus; 0.05, 0.1, and 0.2 mM for suspensions) and benzoic acid (0.2 and 1 mM for callus and 0.05, 0.1, and 0.2 mM for suspensions). Increases in taxol yields of cell suspensions in the presence of the most effective precursors brought taxol amounts at stationary phase from 2 μg · g−1 to approximately 10 μg . g−1 of the extracted dry weight. The results are discussed in termsof possible implications to taxol biosynthesis and in terms of practical applications to large‐scale cell culture systems for the production ofthis drug. © 1994 John Wiley & Sons, Inc.
Use of respiratory quotient as a control parameter for optimum oxygen supply and scale‐up of 2,3‐butanediol production under microaerobic conditions
Authors: Zeng A.‐P. , Byun T.‐G. , Posten C. , Deckwer W.‐D. 
Published: December 2004

AbstractThe respiratory quotient (RQ) was found to be a suitable control parameter for optimum oxygen supply for the production of 2,3‐butanediol + acetoin under microaerobic conditions. In laboratory scale continuous cultures optimum production of 2,3‐butanediol + acetoin was obtained at an RQ value between 4.0 to 4.5. This agreed well with optimum RQ value (4.0) stoichiometrically derived from the bioreactions involved. In fed‐batch cultures product concentrations as high as 102.9 g/L (96.0 g/L butanediol + 6.9 g/L acetoin) can be achieved within 32 h cultivation with an RQ control algorithm for oxygen supply. Under similar conditions only 85.7 g/L product (77.6 g/L butanediol + 8.1 g/L acetoin) was obtained with control of constant oxygen supply rate throughout the cultivation.In pilot scale batch cultures under identical oxygen supply rate the achievable RQ value was found to be strongly influenced by the reactor type and scale. The initial oxygen supply rate influenced the achievable RQ as well. However, in all the reactors studied the specific product formation rate of cells in the exponential growth phase was only a function of RQ. The same optimum RQ value as found in continuous cultures was obtained. It was thus concluded that RQ can be used as a control parameter for optimum production of 2,3‐butanediol + acetoin in both laboratory and pilot plant scale reactors. © 1994 John Wiley & Sons, Inc.
Enhancement of oxygen transfer in highly viscous non‐newtonian fermentation broths
Authors: Kawase Yoshinori , Tsujimura Masanari 
Published: December 2004

AbstractThe influence of short draft tubes covered by perforated plates on gas‐liquid mass transfer was examined in external‐loop airlift bioreactors. The volumetric mass transfer coefficients in a model external‐loop airlift bioreactor were measured with water and non‐Newtonian media. It was found that introduction of draft tubes covered with perforated plates in the riser significantly improved the mass transfer rate, particularly in higher viscous non‐Newtonian fermentation media. The enhancement of mass transfer rate might be due mainly to an increase in bubble coalescence and redispersion. © 1994 John Wiley & Sons, Inc.
Use of plant material for the decontamination of water polluted with phenols
Authors: Dec Jerzy , Bollag Jean‐Marc 
Published: December 2004

AbstractPlant materials were found useful in the decontamination water polluted with phenolic contained in the plant tissue. The enzymes mediated oxidative coupling of the pollutants, followed by precipitation of the formed polymers from the aqueous phase. An industrial wastewater contaminated with 2,4‐dichlorophenol (up to 850 ppm) and other chlorinated phenols was successfully treated using minced horseradish, potato, or white radish (amended with H2O2). Horseradish‐mediated removal of 2,4‐dichlorophenol from model solutions was comparable with that achieved using purified horseradish peroxidase. In addition, horseradish could be reused up to 30 times. Due to the apparent ease of application, the use of plat material may present a breakthrough in the enzyme treatment of contaminated water. © 1994 John Wiley & Sons, Inc.
High‐density algal photobioreactors using light‐emitting diodes
Authors: Lee Choul‐Gyun , Palsson Bernhard Ø. 
Published: December 2004

AbstractLack of high‐density algal photobioreactors (PBR) has been a limitation in exploiting the biotechnological potential of algae. Recent developments of highly efficient light‐emitting diodes (LED using gallium aluminum arsenide chips) have made the development of a small LED‐based PBR possible. We have calculated theoretical values of gas mass transfer requirements and light‐intensity requirement to support high‐density algal cultures for the 680 nm monochromatic red light from LED as a light source. A prototype PBR has been designed based on these calculations. A cell concentration of more than 2 × 109 cells/mL (more than 6.6% v%sol;v), cell doubling times as low as 12 h, and an oxygen production rate as high as 10 mmol oxygen/L culture/h were achieved using on‐line ultrafiltration to periodically provide fresh medium. © 1994 John Wiley & Sons, Inc.
Effect of support material and enzyme pretreatment on enantioselectivity of immobilized subtilisin in organic solvents
Authors: Orsat Bernard , Drtina Gray J. , Williams Michael G. , Klibanov Alexander M. 
Published: December 2004

AbstractSubtilisin Carlsberg was covalently attached to five macroporous acrylic supports of varying aquaphilicity (a measure of hydrophilicity). Kinetic parameters of the transesterification of S and R enantiomers of secphenethyl alcohol with vinyl butyrate, catalyzed by various immobilized subtilisins, were determined in anhydrous dioxane and acetonitrile. Enzyme enantioselectivity in acetonitrile, but not in dioxane, correlated with the aquaphilicity of the support; a mechanistic rationale for this phenomenon was proposed. Although the catalytic activity of immobilized subtilisin in anhydrous solvents strongly depended on enzyme pretreatment, the enantioselectivity was essential conserved. © 1994 John Wiley & Sons, Inc.
Multirate state and parameter estimation in an antibiotic fermentation with delayed measurements
Authors: Gudi R. D. , Shah S. L. , Gray M. R. 
Published: December 2004

AbstractThis article discusses issues related to estimation and monitoring of fermentation processes that exhibit endogenous metabolism and time‐varying maintenance activity. Such culture‐related activities hamper the use of traditional, software sensor‐based algorithms, such as the extended kalman filter (EKF). In the approach presented here, the individual effects of the endogenous decay and the true maintenance processes have been lumped to represent a modified maintenance coefficient,mc. Model equations that relate measurable process outputs, such as the carbon dioxide evolution rate (CER) and biomass, to the observable process parameters (such as net specific growth rate and the modified maintenance coefficient) are proposed. These model equations are used in an estimator that can formally accommodate delayed, infrequent measurements of the culture states (such as the biomass) as well as frequent, culture‐related secondary measurements (such as the CER). The resulting multirate software sensor‐based estimation strategy is used to monitor biomass profiles as well as profiles of critical fermentation parameters, such as the specific growth for a fed‐batch fermentation ofStreptomyces clavuligerus. © 1994 John Wiley & Sons, Inc.
Characterization of a prototype industrial on‐line analyzer for bicarbonate/carbonate monitoring
Authors: Guwy Alan J. , Hawkes Dennis L. , Hawkes Freda R. , Rozzi Alberto G. 
Published: December 2004

AbstractIn many biological reactors bicarbonate is the major species determining pH buffering capacity, or alkalinity. In anaerobic digesters bicarbonate levels should be within 10 to 50 mM for stable operation. Bicarbonate alkalinity in wastewater treatment processes in routinely measured off‐line titrimetrically. Recently we have described the principle of a novel on‐line method of measuring bicarbonate alkalinity. In the prototype device described here, a continuous stream (15 cm3 min−1) of the substrate to be monitored was saturated with gaseous CO2, acidified by the addition of excess acid, and the rate of carbon dioxide evolution, proportional to the concentration of bicarbonate/carbonate in the liquid flow, continuously measured by a sensitive gas meter. The instrument was robust and its response was satisfactory for wastewater treatment process control applications, with linearity in the range 5 to 50 mM HCO3−, a response time in the order of 30 min, and accuracy of the order of 7% in the concentration range 5 to 50 mM sodium bicarbonate. The device was not affected by interference from volatile fatty acids, does not make use of pH probes which in many wastes are subject to fouling, and may form the basis of a digester control strategy. © 1994 John Wiley & Sons, Inc.
Effects of diffusion limitation on immobilized nitrifying microorganisms at low temperatures
Authors: Wijffels R. H. , Hunik J. H. , Leenen E. J. T. M. , Günther A. , de Castro J. M. Obón , Tramper J. , Englund G. , Bakketun Å. 
Published: December 2004

AbstractActivation energies of suspended and immobilized nitrifying bacteria were determined and compared to determine if diffusion limitation results in decreased sensitivity for temperature. The activation energy for the respiration activity of suspended Nitrosomonas europaea and Nitrobacter agilis was found to be 86.4 and 58.4 kJ mol−1, respectively. The activation energy for oxygen diffusion in the support material, κ‐carrageenan, determined from the effect of temperature on the effective diffusion coefficient (D), was 17.2 kJ mol−1. Consequently, the apparent actvation energy of diffusion limited cells should be lower. It was indeed shown that due to the effect of diffusion limitation and to temperature effects on the Monod constant Ks, the immobilized‐cell activity was less sensitive to temperature. The apparent activation energy for immobilized Ns. europaea was between 28.6 and 94.2 kJ mol−1 and for immobilized Nb. agilis between 1.4 and 72.9 kJ mol−1, depending on the oxygen concentration and temperature. © 1995 John Wiley & Sons, Inc.
Rheologies and morphologies of three actinomycetes in submerged culture
Authors: Warren S. J. , Keshavarz‐Moore E. , Shamlou P. Ayazi , Lilly M. D. , Thomas C. R. , Dixon K. 
Published: December 2004

AbstractThe broth rheologies and morphologies of three actinomycetes (Saccharopolyspora erythraea, Actinomadura roseorufa, and Streptomyces rimosus) in submerged culture have been examined. The rheology of all the broths became pseudoplastic as soon as significant growth occurred with the power law index, n, falling to 0.20 to 0.25. The consistency index, K, rose with biomass concentration although in some instances it fell later in the fermentation. The mean main hyphal lengths of all cultures were in the range, 15 to 25 μm, and did not alter greatly even when large changes in K were occurring. © 1995 John Wiley & Sons, Inc.
Real‐time fuzzy‐knowledge‐based control of Baker's yeast production
Authors: Siimes Terhi , Linko Pekka , von Numers Camilla , Nakajima Mikio , Endo Isao 
Published: December 2004

AbstractA real‐time fuzzy‐knowledge‐based system for fault diagnosis and control of bioprocesses was constructed using the object‐oriented programming environment Small‐talk/V Mac. The basic system was implemented in a Macintosh Quadra 900 computer and built to function connected on line to the process computer. Fuzzy logic was employed in handling uncertainties both in the knowledge and in measurements. The fuzzy sets defined for the process variables could be changed on‐line according to process dynamics. Process knowledge was implemented in a graphical two‐level hierachical knowledge base. In on‐line process control the system first recognizes the current process phase on the basis of top‐level rules in the knowledge‐base. Then, according to the results of process diagnosis based on measurement data, the appropriate control strategy is subsequently inferred making use of the lower level rules describing the process during the phase in question. © 1995 John Wiley & Sons, Inc.
Amplification of toluene dioxygenase genes in a hybrid Pseudomonas strain to enhance the biodegradation of benzene, toluene, and p‐xylene mixture
Authors: Lee Jang‐Young , Jung Kwan‐Hye , Kim Hak‐Sung 
Published: December 2004

AbstractA hybrid metabolic pathway through which benzene, toluene, and p‐xylene (BTX) mixture could be simultaneously mineralized was previously constructed in Pseudomonas putida TB101 (Lee, Roh, Kim, Biotechnol. Bioeng 43: 1146–1152, 1994). In this work, we improved the performance of the hybrid pathway by cloning the todC1C2BA genes in the broad‐host‐range multicopy vector RSF1010 and by introducing the resulting plasmid pTOL037 into P. putida mt‐2 which harbors the archetypal TOL plasmid. As a result, a new hybrid strain, P. putida TB103, possessing the enhanced activity of toluene dioxygenase in the hybrid pathway was constructed. The degradation rates of benzene, toluene, and p‐xylene by P. putida TB103 were increased by about 9.3‐, 3.7‐, and 1.4‐fold, respectively, compared with those by previously constructed P. putida TB101. Apparently, this improved capability of P. putida TB103 for the degradation of BTX mixture resulted from the amplification of the todC1C2BA genes. Furthermore, a relatively long lag period for benzene degradation observed when P. putida TB101 was used for the degradation of BTX mixture at low dissolved oxygen (DO) tension disappeared when P. putida TB103 was employed. © 1995 John Wiley & Sons, Inc.
Evaluation and applications of optical cell density probes in mammalian cell bioreactors
Authors: Wu P. , Ozturk S. S. , Blackie J. D. , Thrift J. C. , Figueroa C. , Naveh D. 
Published: December 2004

AbstractOn‐line optical cell density probes were implemented to continuously monitor the cell densities in mammalian cell bioreactor and to achieve advanced bioreactor controls. We tested cell density probes from six manufacturers in high cell density bioreactors. When externally calibrated, Aquasant and Ingold backscattering probes produced the most linear probe responses (PR) versus cell density (CD), followed by the ASR and Cerex laser probes. Monitek and Wedgewood transmission probes had lower resolutions. All probes were tested in two murine hybridoma fermentations. Cell densities varied between 1 × 106 cells/mL to 20 × 106 cells/mL and the bioreactors were operated for 5 to 7 weeks. For our bioreactors, Aquasant, Ingold, ASR, Wedgewood, and Monitek probes gave satisfactory responses. Little fouling was observed with any probe at the end of 2 weeks. Fouling was a possibility after 3 weeks in one bioreactor but its effect can be easily corrected. Cell density control and specific perfusion control of bioreactors based on the Aquasant probe were achieved. Implementation of cell density probe based perfusion control, instead of “step perfusion adjustments” based on manual hemacytometer control, will result in smoother operation, healthier cultures, increased medium delivery efficiency, and reduced operational excursions. © 1995 John Wiley & Sons, Inc.
Quantitative analysis of biofilm thickness variability
Authors: Murga Ricardo , Stewart Philip S. , Daly Don 
Published: December 2004

AbstractThe thickness variability of biofilms of Pseudomonas aeruginosa, Klebsiella pneumoniae, and the binary population combination of these two species was quantified. The experimental method involved cryoembedding biofilms with a commercial tissue embedding agent, sectioning, and applying image analysis to construct thickness profiles along linear transects (up to 1 cm in length) across the substratum. Biofilms embedded and sectioned by this method were locally as thin as a single cell attached to the surface (<5 μm) and as thick as 1000 μm. Week‐old biofilms of three different species compositions displayed distinct structural features as indicated by their mean thicknesses and by a roughness coefficient. Monopopulation biofilms of P. aeruginosa (29 μm mean thickness) or K. pneumoniae (100 μm mean thickness) were thinner than the binary population biofilm (400 μm mean thickness). A roughness coefficient developed in this investigation corroborated the qualitative visual characterization of P. aeruginosa biofilms as relatively uniformly thick (mean roughness coefficient 0.15), K. pneumoniae biofilms as patchy (mean roughness coefficient 1.14), and the binary population biofilm as intermediate (mean roughness coefficient 0.26). Whereas P. aeruginosa and binary population biofilms covered the substratum completely, significant areas of essentially bare substratum were apparent in K. pneumoniae biofilms. The patchiness of K. pneumoniae biofilms may be due to the fact that this organism is nonmotile. A spatial correlation analysis of the thickness data indicated that thickness measurements were still correlated even when separated by distances that exceeded the mean biofilm thickness. Cell aggregates, some of them hundreds of microns in size, were observed in the effluent of K. pneumoniae and binary population biofilm reactors. Measurements of thickness variability and other observations reported in this article provide a quantitative basis for analysis of microscale structural heterogeneity of biofilms. © 1995 John Wiley & Sons, Inc.
Mass balancing in kinetic resolution: Calculating yield and enantiomeric excess using chiral balance
Authors: Straathof A. J. J. , Rakels J. L. L. , Heijnen J. J. 
Published: December 2004

AbstractWhen kinetic resolution is applied for the production of enantiomerically pure compounds, process options may be used which involve more than one chiral substrate and one chiral product, such as sequential or parallel enzymatic kinetic resolutions or hydrolysis of diastereomers. Although the relation between the yields (y) of the chiral compounds is straightforward in these cases, the relation between their enantiomeric excess (ee) values is not. Combining mass balances into a so‐called chiral balance (Σ y · eeR = 0) provides the relation between enantiomeric excess values in a useful manner. This chiral balance easily shows which nonmeasured enantiomeric excess values and yields can be calculated from measured values. The chiral balance is only valid when configurations at chiral centers are conserved. © 1995 John Wiley & Sons, Inc.
Reduction of nitrate and nitrite in a cyclically operated continuous biological reactor
Authors: Wang J.‐H. , Baltzis B. C. , Lewandowski G. A. 
Published: December 2004

AbstractBiological reduction of nitrate and nitrite was studied with a continuously operated cyclic reactor. The medium was fed to the reactor during the first phase of the cycle, and the effluent was drawn from the reactor during the third phase of the cycle; reaction occurred throughout the cycle. The process was described mathematically based on kinetic expressions revealed in an independent study. The model equations were subjected to detailed analysis with numerical codes based on the bifurcation theory for forced systems. The analysis has shown that in the operating parameter space there are extensive regions where the system can reach up to three different periodic states. The results of this analysis are shown in the form of two‐dimensional operating diagrams. Numerical results have also shown that under certain operating conditions nitrate can be completely eliminated, while nitrite remains practically untreated. An experimental unit was designed, constructed, and used in experiments with a strain of Pseudomonas denitrificans [American Type Culture Collection (ATCC) 13867] under different operating conditions. The experimental results confirmed the theoretical predictions both qualitatively and quantitatively. Conditions under which complete reduction of both nitrate and nitrite is achieved, were found and experimentally verified. The results of this study suggest a methodology for analysis and design of cyclically operated bioreactors employed in denitrification of wastewaters. © 1995 John Wiley & Sons, Inc.
Mathematical model of self‐cycling fermentation
Authors: Wincure B. M. , Cooper D. G. , Rey A. 
Published: December 2004

AbstractThis article presents a mathematical model for biomass, limiting substrate, and dissolved oxygen concentrations during stable operation of self‐cycling fermentation (SCF). Laboratory experiments using the bacterium Acinetobacter calcoaceticus RAG‐1 and ethanol as the limiting substrate were performed to validate the model. A computer simulation developed from the model successfully matched experimental SCF intracycle trends and end‐of‐cycle results and, most importantly, settled into an unimposed periodicity characteristic of stable SCF operation. © 1995 John Wiley & Sons, Inc.
Modeling of an industrial alcohol fermentation and simuiation of the plant by a process simulator
Authors: Pascal F. , Dagot C. , Pingaud H. , Corriou J. P. , Pons M. N. , Engasser J. M. 
Published: December 2004

AbstractThe aim of the present study was the development of a general simulation module for fermentation within the framework of existing chemical process simulators. This module has been applied to an industrial plant which produces ethanol from beet molasses and fresh beet juice by Saccharomyces cerevisiae. An unstructured mechanistic model has been developed with kinetic laws that are based on a chemically defined reaction scheme which satisfies stoichiometric constraints. This model can be applied to different culture conditions and takes into account secondary byproducts such as higher alcohols. These byproducts are of prime importance and need to be correctly estimated because a sequence of distillation columns follow the fermentor in the plant. Important measurement campaigns have been performed on the plant to validate the model. Plant operation has been successfully simulated using the same kinetic model for both continuous and fed‐batch modes of production. © 1995 John Wiley & Sons, Inc.