bluuebunny/crossref_metadata_2025_split huggingface dataset:
High oxygen transfer rate in a new aeration system using hollow fiber membrane
Authors: Matsuoka Hiroshi , Fukada Shouhei , Toda Kiyoshi 
Published: December 2004

AbstractA new type of bubble aeration column called a hollow fiber membrane (HFM) aeration column was proposed, which was featured in the use of hollow fiber membranes and gave a high bubble density in the column. The value of kLa was increased by modifying the membrane surface for making the pore size smaller. The Sauter mean diameter of bubbles (Dvs) was 2.0 ± 0.1 mm in the range of the superficial gas velocity from 0.02 m s−1 to 0.065 m s−1, while that obtained for the bubbles near the membrane was 811 μm at the superficial gas velocity of 4.0 × 10−4 m s−1. The difference was ascribed to the effect of coalescence of bubbles. The value of KLa increased in proportion to the superficial gas velocity up to 0.02 m s−1, and was almost constant above 0.03 m s−1. The maximum value of kLa, 2.5 s−1, was higher than those of the other aeration columns reported previously. The pneumatic power consumption per unit liquid volume (Pv) for obtaining the same kLa was the smallest in the HFM aeration columns. Pv, for obtaining the same interfacial area of bubbles per liquid volume, was also lower than those for other types of aeration columns. It was suggested from the measurement of bubble diameter that the larger interfacial area generated in the HFM aeration column ascribes to the larger gas holdup than the smaller Dvs. © 1992 John Wiley & Sons, Inc.
Direct measurement of the yield stress of filamentous fermentation broths with the rotating vane technique
Authors: Leong‐Poi Lisa , Allen D. Grant 
Published: December 2004

AbstractThe existence of a yield stress in filamentous fermentation broths has important transport phenomena implications in the design and operation of bioreactors. In this study, the constant shear rate vane method was assessed for directly measuring the yield stress of filamentous Aspergillus niger fermentation broths, as well as model fluids (ketchup, yogurt, and pulp suspensions). The method involved rotating 4‐, 6‐, and 8‐bladed vanes (7.2 cm ≤ height ≤ 15 cm; 4.0 cm ≤ dia. ≤ 6 cm) at speeds of 0.01 to 0.64 rpm in the fluid and plotting the torque as a function of time. Based on visual observations, the consistency of the results with vane type and speed and comparison with previous work on nonbiological samples, it was concluded that the method is an effective and consistent technique for yield stress measurements on filamentous fermentation broths. Based on comparisons with concentric cylinder viscometer results, it was also concluded that the value determined via the vane method was a “static” yield stress (values of up to 28 Pa) which was much greater than the extrapolated (or “dynamic”) yield stress determined via the concentric cylinder viscometer. © 1992 John Wiley & Sons, Inc.
Colloidal gold as a biocompatible immobilization matrix suitable for the fabrication of enzyme electrodes by electrodeposition
Authors: Crumbliss A. L. , Perine S. C. , Stonehuerner J. , Tubergen K. R. , Zhao Junguo , Henkens R. W. , O'Daly J. P. 
Published: December 2004

AbstractGlucose oxidase, horseradish peroxidase, xanthine oxidase, and carbonic anhydrase have been adsorbed to colloidal gold sols with good retention of enzymatic activity. Adsorption of xanthine oxidase on colloidal gold did not result in a change in enzymatic activity as determined by active site titration with the stoichiometric inhibitor pterin aldehyde and by measurement of the apparent Michaelis constant (K′M). Gold sols with adsorbed glucose oxidase, horseradish peroxidase, and xanthine oxidase have also been electrodeposited onto conducting matrices (platinum gauze and/or glassy carbon) to make enzyme electrodes. These electrodes retained enzymatic activity and, more importantly, gave an electrochemical response to the enzyme substrate in the presence of an appropriate electron transfer mediator. Our results demonstrate the utility of colloidal gold as a biocompatible enzyme imobilization matrix suitable for the fabrication of enzyme electrodes. © 1992 John Wiley & Sons, Inc.
Effect of reducing agents in an aerobic amino acid fermentation
Authors: Kwong Simon C. W. , Rao Govind 
Published: December 2004

AbstractThis study focuses on the effects of the reducing agents, dithiothreitol (DTT) and glutathione (GSH), on amino acid production in aerobically growing Corynebacterium glutamicum. The problem of reducing agent addition affecting the dissolved oxygen level was solved by positioning the culture at a high dissolved oxygen level and feeding the reducing agent into the fermentor. We show that it is possible to lower the redox potential even in a highly aerobic environment. The addition of DTT to the fermentation during the growth phase caused a significant increase in specific amino acid production rate and total amino acids produced, as compared with a control. In contrast, GSH had an inhibitory effect. © 1992 John Wiley & Sons, Inc.
Kinetics and stoichiometry of growth of plant cell cultures of Catharanthus roseus and Nicotiana tabacum in batch and continuous fermentors
Authors: van Gulik W. M. , ten Hoopen H. J. G. , Heijnen J. J. 
Published: December 2004

AbstractPlant cell suspension cultures of Catharanthus roseus and Nicotiana tabacum were grown in stirred tank bioreactors operated in batch and continuous mode. The stoichiometry of growth of both species in steady‐state glucose limited chemostats was studied at a range of different dilution rates. A linear relation was applied to describe specific glucose uptake, oxygen consumption, and carbon dioxide production as a function of the growth rate. Specific respiration deviated greatly from the linear relation. An unstructured mathematical model, based on the observed stoichiometry in the glucose limited chemostats, was applied to describe the growth in batch culture. From a comparison between the observed growth pattern in batch fermentors and computer simulations it appeared that the stoichiometry of growth of the C. roseus culture was different under steady‐state and dynamic conditions. It was concluded that a mathematical model for the growth of suspension culture plant cells in which the biomass is considered to be a single compound with an average chemical composition is of limited value because large changes in the conmposition of the biomass may occur. © 1992 John Wiley & Sons, Inc.
Mechanism of insulin aggregation and stabilization in agitated aqueous solutions
Authors: Sluzky Victoria , Klibanov Alexander M. , Langer Robert 
Published: December 2004

AbstractUndesirable aggregation of aqueous insulin solutions remains a serious obstacle in the development of alternative methods of diabetes therapy. We investigated the fundamental nature of the aggregation mechanism and proposed stabilization strategies based on a mathematical model for the reaction scheme. Insulin aggregation kinetics in the presence of solid‐liquid and air–liquid interfaces were monitored using UV spectroscopy and quasielastic light scattering (QELS). Experimental observations were consistent with our model of monomer denaturation at hydrophobic surfaces followed by the formation of stable intermediate species which facilitated subsequent macroaggregation. The model was used to predict qualitative trends in insulin aggregation behavior, to propose stabilization strategies, and to elucidate mechanisms of stabilization. In the absence of additives, insulin solutions aggregated completely (more than 95% of the soluble protein lost) within 24 h; with sugarbased nonionic detergents, no detectable loss occurred for more than 6 weeks. © 1992 John Wiley & Sons, Inc.
Investigation of reduced serum and serum‐free media for the cultivation of insect cells (Bm5) and the production of baculovirus (BmNPV)
Authors: Zhang Junli , Kalogerakis Nicolas , Behie Leo A. , Iatrou Kostas 
Published: December 2004

AbstractAn experimental study has been carried out to investigate the effectivenes of several reduced serum and serum‐free media for the cultivation of an ovarian cell line, Bm5, of the lepidopteran insect Bombyx mori. Bm5 cell were successfully adapted to grow in a medium containing 5% serum and a serum‐free medium (EX‐CELL 400). On the other hand, this cell line could not be adapted to grow in several other media suggested in the literature, including IPL‐41 + 2% fetal bovine serum (FBS), SF‐900, and a serum‐free medium (ISFM). Furthermore, a comparative study was conducted to determine the production levels of B. mori nuclear polyhedrosis virus (BmNPV) in Bm5 cells cultured in three different medium formulations. The production levels of BmNPV in adapted Bm5 cells grown in a 5% serum‐supplemented medium and a serum‐free medium (EX‐CELL 400) were comparable to those obtained in Bm5 cells grown 10% serum‐supplemented medium. © 1992 John Wiley & Sons, Inc.
Nutrient‐dependent selection of morphological mutants ofFusarium graminearumA3/5 isolated from long‐term continuous flow cultures
Authors: Wiebe Marilyn G. , Robson Geoffrey D. , Cunliffe Bryan , Trinci Anthony P. J. , Oliver Stephen G. 
Published: December 2004

AbstractHighly branched (colonial) mutants (MC1‐1‐, CC1‐1, and C106) ofFusarium graminearumA3/5 were each grown with the parental strain (A3/5) in continuous flow cultures at high and low dilution rates using a variety of nutrient limitations. MC1‐1 replaced A3/5 in all nutrient‐limited cultures tested (glucose‐, Mg2+‐, ammonium‐, and sulphate‐limited cultures), suggesting that it has a higher maximum specific growh rate than A3/5. Compared with A3/5, C106 was positively selected for in Mg2+‐limited cultures and its selection coefficient was higher at low than at high dilution rates, suggesting that, compared with A3/5, it has a reduced saturation constant (Ks) for Mg2+. However, in batch culture, C106 and A3/5 had the same (15 μM) appaentKsvalue for Mg2+. C106 was replaced (negative selection coefficient) by A3/5 in gluose‐, ammonium‐, and phsophate‐limited continuous flow cultures, but was neither at an advantage nor a disadvantage (i.e., it behaved as a neutral mutation) in sulphate‐limited cultures. CC1‐1 replaced A3/5 when they were grown together in glucose‐, maltose‐, or ribose‐limited continuous flow cultures, but not in fructose‐, xylose‐, ammonium‐, or phsophate‐limited cultures. Because A3/5 and CC1‐1 had similarKmvalues (30 μM) for glucose, and because the selective advantage of CC1‐1 was maintained in maltose‐limited cultures (maltose was not hydrolyzed extracellularly), it was concluded that the selective advantage of CC1‐1 did not result from it having a lowerKsfor glucose than the parental strain. Rather, the data suggested that the activity of phosphoketopentoepimerase may be altered by the CC1‐1 mutation. © 1992 John Wiley & Sons, Inc.
Optimizing the sample size and the retention parameters to achieve maximum production rates for enantiomers in chiral chromatography
Authors: Jacobson Stephen C. , Felinger Attila , Guiochon Georges 
Published: December 2004

AbstractThe optimum experimental conditions (sample size and mobile phase composition) are calculated for maximum production rate of either one of two enantiomers contained in feeds of different compositions (1/1, 1/10, and 10/1). The products are obtained at 99% purity. The calculations use the equilibrium‐dispersive model of chromatography and the equilibrium isotherms determined experimentally from the rear, diffuse boundary of overloaded elution profiles. The production rate measured experimentally under the optimum conditions calculated agree with 4% of the calculated values. There is an optimum value for the retention factor which is higher than predicted by a model assuming constant separation factor, because both separation factor and retention decrease with increasing organic solvent concentration in the mobile phase. © 1992 John Wiley & Sons, Inc.
Oxygen uptake rates in cultured rat hepatocytes
Authors: Rotem Avi , Toner Menmet , Tompkins Ronald G. , Yarmush Martin L. 
Published: December 2004

AbstractOne potential treatment of acute liver failure involves the use of an extracorporeal device composed of functional hepatocytes. A major issue in the design of such a large‐scale device is providing the hepatocytes with a sufficient supply of oxygen and other nutrients. In this study, we have designed and characterized a simple perfusion system hepatocytes using this system. The OUR of hepatocytes was determined during the first day after seeding on a single collagen gel and during the long‐term stable culture after the addition of a top layer of collagen. The OUR increased to 20.7 ± 0.57 pmol/sec/μg DNA during the first 13 hours of culture on a single collagen gel, while during the next 11 hours, the OUR declined to 10.6 ± 1.5 pmol/sec/μg DNA. In parallel with the increase in OUR during the first 10 hours, we observed significant cell spreading, suggesting that the oxygen supply to the cells may be critical for the spreading and adaptation of the anchorage‐dependent hepatocytes following isolation. Addition of a top layer of collagen to hepatocyte cultures for 24 hours of culture on a single collagen layer resulted in a stable OUR for 15 days. These results indicate that OUR of hepatocytes in culture may vary depending on the phase of culture (i.e., early vs. late) and on the extracellular environment. © 1992 John Wiley & Sons, Inc.
Influence of oxygen tension, biomass concentration, and specific growth rate on the rheological properties of a filamentous fermentation broth
Authors: Olsvik E. S. , Kristiansen B. 
Published: December 2004

AbstractThe influence of oxygen tension, biomass concentration, and specific growth rate on the rheological properties of an Aspergillus niger fermentation broth was investigated by growing the fungus in continuous culture. The rheological properties were measured on‐line using an impeller rheometer system. The effect of the specific growth rate on broth rheology was strongly influenced by the dissolved oxygen, (DO) concentration in the broth. At DO concentrations above 10% of saturation, K increased with the dilution rate, and at DO concentrations below 10% of saturation, K decreased with increasing dilution rate. The largest influence of a change in the DO concentration on the viscosity of the broth was found at the lowest growth rates and the lowest DO concentrations. K/x, a term that gives a simple description of the structure or the morphology of the culture, was found to increase with biomass concentration. © 1992 John Wiley & Sons, Inc.
Purification of recombinant protein A by aqueous two‐phase extraction integrated with affinity precipitation
Authors: Kamihira Masamichi , Kaul Rajni , Mattiasson Bo 
Published: December 2004

AbstractAqueous two‐phase extraction incorporated affinity precipitation was examined as a technique for protein purification. An enteric coating polymer, Eudragit S100, was employed as a ligand carrier. Eudragit was specifically partitioned to the top phase in the aqueous two‐phase systems. For application of this method to purification of recombinant protein A using human IgG coupled to Eudragit in an aqueous two‐phase system, 80% of protein A added was recovered with 81% purity. The purity was enhanced 26‐fold by thid method. The IgG‐Eudragit could be used repeatedly for the purification process. This seperation method should be applicable to industrial‐scale purification as a new purification procedure combining the advantages and compensating for the disadvantages of the aqueous two‐phase method and affinity precipitation method. © 1992 John Wiley & Sons, Inc.
Mineralization of biphenyl and PCBs by the white rot fungus Phanerochaete chrysosporium
Authors: Thomas Daniel R. , Carswell Kathleen S. , Georgiou George 
Published: December 2004

AbstractThe white rot fungus Phanerochaete chrysosporium is unique in its ability to totally degrade a wide variety of recalcitrant pollutants. We have investigated the degradation of biphenyl and two model chlorinated biphenyls, 2,2′,4,4′‐tetrachlorobiphenyl and 2‐chlorobiphenyl by suspended cultures of P. chrysosporium grown under conditions that maximize the synthesis of lignin‐oxidizing enzymes. Radiolabeled biphenyl and 2′‐chlorobiphenyl added to cultures at concentrations in the range 260 nM to 8.8 μM were degraded extensively to CO2 within 30 days. In addition, from 40% to 60% of the recovered radioactivity was found in water‐soluble compounds. A correlation between the rate of degradation and the synthesis of ligninases or Mn‐dependent peroxidases could not be observed, indicating that yet unknown enzymatic system may be resonsible for the initial oxidation of PCBs. The more heavily chlorinated PCB congener, 2,2′,4,4′‐tetrachlorobiphenyl was converted to CO2 less readily; approximately 9% and 0.9% mineralization was observed in cultures incubated with 40 nM and 5.3 μM, respectively. Overall, our results indicate that P. chrysosporium is a promising organism for the treatment of wastes contaminatd with lightly and moderately chlorinated PCBs. © 1992 John Wiley & Sons, Inc.
Biodegradation of an inhibitory nongrowth substrate (nitroglycerin) in batch reactors
Authors: Pesari Harish , Grasso Domenic 
Published: December 2004

AbstractBiodegradation of nitroglycerin (NG), an inhibitory, nongrowth substrate present in a multicomponent munition wastewater, was investigated in a pilot‐scale batch reactor operated with both aerobic and anoxic cycles. A mixed culture was initially acclimated by gradual introduction of NG into influent and subsequently exposed to actual NG‐laden production wastewater. System performance revealed that NG was amenable to aerobic biodegradation without adverse impact on removal efficiencies of other pollutants. Temporal NG concentration profiles indicated that an influent concentration of approximately 200 mg/L of NG was reduced to below detection limits in less than 5 h of aeration with no appreciable (<4%) biosorption. Failure of NG‐acclimated cultures to utilize NG as a sole carbon source in bench‐scale reactors suggested that NG behaved as a non‐growth substrate and its degradation possibly occurred by cometabolism. Ethyl acetate present in the waste stream was an adequate growth substrate in terms of both biological and physicochemical properties. High concentrations of NO3‐N, produced as a result of aerobic degradation of NG and other nitrogenous compounds of the waste, were treated in an anoxic phase. Approximately 95 mg/L of NO3‐N was denitrified to below detection limits in 5 h of anoxia without the addition of external carbon sources. Two SRB cycle schemes with different static‐fill times exhibited significant differences in treatment efficiencies. © 1993 John Wiley & Sons, Inc.
Cultivation of mammalian cells as aggregates in bioreactors: Effect of calcium concentration of spatial distribution of viability
Authors: Peshwa Madhusudan V. , Kyung Yun‐Seung , McClure Don B. , Hu Wei‐Shou 
Published: December 2004

AbstractRecombinant human kidney epithelial 293 cells were cultivated as aggregates in suspension. The concentration calcium ion, in the range of 100 μM to 1mM, affected the rate of aggregate formation. During the course of cultivation the size distribution of aggregates shifted and the fraction of larger aggregates increased. This effect was more profound in cultures with a high calcium concentration. Scanning and transmission microscopic examination of the aggregates revealed that cell packing was greater in the high calcium cultures and that ultrastructural integrity was retained in aggregates from both low and high calcium cultures. Confocal microscopy was applied to examine the viability of cells in the interior of the aggregates. High viability was observed in the aggregates obtained from exponentially growing cultures. Aggregates from the high calcium culture in the stationary phase exhibited lower viability in the interior. With its ease of retention in a perfusion bioreactor, aggregate cultures offer an alternative choice for large‐scale operation. © 1993 John Wiley & Sons, Inc.
Plasmid retention and gene expression in suspended and biofilm cultures of recombinant Escherichia coli DH5α(pMJR1750)
Authors: Huang Ching‐Tsan , Peretti Steven W. , Bryers James D. 
Published: December 2004

AbstractDifferences in plasmid retention and expression are studied in both suspended and biofilm cultures of Escherichia coli DH5α(PMJR1750). An alternative mathematical model is proposed which allows the determination of plasmid loss probability in both suspended batch and continuously fed biofilm cultures. In our experiments, the average probability of plasmid loss of E. coli DH5α(pMJR1750) is 0.0022 in batch culture in the absence of antibiotic selection pressure and inducer. Under the induction of 0.17 MM IPTG, the maximum growth rate of plasmid‐bearing cells in suspended batch culture dropped from 0.45 h−1 to 0.35 h−1 and the β‐galactosidase concentration reached an experimental maximum of 0.32. pg/cell 4 hours after the initiation of induction. At both 0.34 and 0.51 mM IPTG, growth rates in batch cultures decreased to 0.16 h−1, about 36% of that without IPTG, and the β‐galactosidase concentration reached an experimental maximum of 0.47 pg/cell 3 hours after induction.In biofilm cultures, both plasmid‐bearing and plasmid‐free cells in increase with time reaching a plateau after 96 hours n the absence of both the inducer and any antibiotic selection pressure. Average probability of plasmid loss for biofilm‐bound E. coli DH5β(pMJR1750) population was 0.017 without antibiotic selection. Once the inducer IPTG was added, the concentration of plasmid‐bearing cells in biofilm dropped dramatically while plasmid‐free cell numbers maintained unaffected. The β‐galactosidase concentration reached a maximum in all biofilm experiments 24 hours after induction; they were 0.08, 0.1, and 0.12 pg/cel under 0.17, 0.34, and 0.51 mM IPTG, respectively. © 1993 John Wiley & Sons, Inc.
Defined media optimization for growth of recombinant Escherichia coli X90
Authors: Yee L. , Blanch H. W. 
Published: December 2004

AbstractAn optimized, defined minimal medium was developed to support balanced growth of Escherichia coli X90 harboring a recombinant plasmid. Foreign protein expression was repressed in these studies. A pulse injection technique was used to identify the growth responses to nutrients in a chemostat. Once the nutrients essential for growth had been identified, the yield coefficients for individual medium components. These yield coefficients were used to develop an optimized, glucose‐limited defined minimal medium that supports balanced cell growth in chemostat culture. The biomass and substrate concentrations follow the Monod chemostat model. The maximum specific growth rate determined in a washout experiment is 0.87 h−1 for this strain in the optimized medium. the glucose yield factor is 0.42 g DCW/g glucose and the maintenance coefficient is zero in the glucose‐limited chemostat culture. © 1993 John Wiley & Sons, Inc.
In vitro production of Bombyx mori silk fibroin by organ culture of the posterior silk glands; isotope labeling and fluorination of the silk fibroin
Authors: Asakura Tetsuo , Sakaguchi Ryuji , Demura Makoto , Manabe Takuro , Uyma Atsuo , Ogawa Katsuaki , Osanai Minoru 
Published: December 2004

AbstractAn in vitro silk fibroin production system has been developed by culture of posterior silk glands from Bombyx mori. A large amount of the silk fibroin was produced continuously and effectively with a rotation culture procedure. Modified Grace's insect medium was used, and oxygen bubbling in the medium was performed. In addition, half of the medium was replaced with fresh medium every 6 h. The production yield of silk fibroin produced after 100 h culture was 81 mg/g wet weight of posterior silk gland. This culture system was used successfully for efficient 15N isotope labeling of silk fibroin, which is required for 15N solid state nuclear magnetic resonance (NMR) analysis of silk fibroin. Moreover, the introduction of fluorinated amino acids into silk fibroin was also carried out using this culture system. © 1993 John Wiley & Sons, Inc.