bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatial distribution of mammalian cells dictated by material surface chemistry
Authors: Healy Kevin E. , Lom Barbara , Hockberger Philip E. 
Published: December 2004

AbstractAnisotropic cell culture surfaces patterned with amino and alkylsilanes can guide cell distribution and provide an approach to study important processes involved in tissue engineering, such as cell attachment and locomotion. By combining photolithographic and silane coupling techniques, glass coverslips were patterned with either n‐octadecyldimethylchlorosilane (ODDMS) or dimethyldichlorosilane (DMS), and N‐(2‐aminoethyl)‐3‐aminopropyl‐trimethoxysilane (EDS). The alkylsilanes, theoretically, have similar methyl and methylene groups exposed at the surface but different structures, with DMS being amorphous and ODDMS ordered. Neuroblastoma cells, osteosarcoma cells, and fibroblasts plated on surfaces patterned with EDS/ODDMS and EDS/DMS specifically localized on the EDS regions, but distributed randomly on ODDMS/DMS patterned surfaces. The preferential assembly of cells onto EDS regions did not depend on the structure of the adjacent alkylsilane regions and was a time‐dependent process. Angle dependent x‐ray photoelectron spectroscopy (XPS) and contact angle measurements indicated that EDS was imobilized on glass as a fractional hydrophilic monolayer, and ODDMS and DMS were bound as patchy amorphous hydrophobic multilayers. Neither surface coverage nor thickness of the overlayer seemed to be as important as surface chemistry, or charge, in guiding mammalian cell distribution. These results are consistent with the concept that mammalian cells attach to and are guided by positively charged surfaces.
Crossflow filtration of yeast broth cultivated in molasses
Authors: Tanaka Takaaki , Kamimura Ryoji , Fujiwara Ryo , Nakanishi Kazuhiro 
Published: December 2004

AbstractA broth of yeast cells cultivated in molasses was crossfiltered with a thin‐channel module. The permeation flux gradually decreased at a constant cell concentration. The flux was much lower than that obtained for yeast broth cultivated in yeast extract, polypeptone, and dextrose (YPD) medium during the filtration. The flux did not depend on the membrane pore size (0.45 to 5 μm). The steady‐state flux was one‐twentieth that calculated for a cake filtration mode from the amount of cake per unit filtration area and the specific resistance of the cake measured in a dead‐end filtration apparatus. The lower flux was due to small particles (most of which were less than 1 μm in diameter) in the molasses. The mehanism of crossflow filtration of broths of yeast cells cultivated in molasses was clarified by analysis of the change in flux with time and observations with scanning electron microscopy. At the initial stage of crossflow filtration the yeast cells and particles from the molasses were deposited on the membrane to form the molasses were deposited on the membrane to form a cake in a similar way to dead‐end filtration. After the deposition of cells onto the membrane ceased, the fine particles from molasses formed a thin layer, which had higher resistance than the cake formed next to the membrane. The backwashing method was effective to increase the flux. The flux increased low when the pore size was 0.45 to 0.08 μm, but using larger pores of 3 to 5 μm it returned almost to the bases line. © 1994 John Wiley & Sons, Inc.
Continuous propionate production from whey permeate using a novel fibrous bed bioreactor
Authors: Yang Shang‐Tian , Zhu Hui , Li Ying , Hong Gene 
Published: December 2004

AbstractContinuous production of propionate from whey lactose by Propionibacterium acidipropionici immobilized in a novel fibrous bed bioreactor was studied. In conventional batch propionic acid fermentation, whey permeate without nutrient supplementation was unable to support cell growth and failed to give satisfactory fermentation results for over 7 days. However, with the fibrous bed bioreactor, a high fermentation rate and high conversion were obtained with plain whey permeate and de‐lactose whey permeate. About 2% (wt/vol) propionic acid was obtained from a 4.2% lactose feed at a retention time of 35 to 45 h. The propionic acid yield was ∼46% (wt/vol) from lactose. The optimal pH for fementation was 6.5, and lower fermentation rates and yields were obtained at lower pH values. The optimal temperature was 30°C, but the temperature effect was not dramatic in the range of 25 to 35°C. Addition of yeast extract and trypticase to whey permeate hastened reactor startup and increased the fermentation rate and product yields, but the addition was not required for long‐term reactor performance. The improved fermentation results with the immobilized cell bioreactor can be attributed to the high cell density, ∼50 g/L, attained in the bioreactor, Cells were immobilized by loose attachement to fiber surfaces and entrapment in the void spaces within the fibrous matrix, thus allowing constant renewal of cells. Consequently, this bioreactor was able to operate continuously for 6 months without encountering any clogging, degeneration, or contamination problems. Compared to conventional batch fermentors, the new bioreactor offers many advantages for industrial fermentation, including a more than 10‐fold increase in productivity, acceptance of low‐nutrient feedstocks such as whey permeate, and resistance to contamination. © 1994 John Wiley & Sons, Inc.
Growth characteristics in fed‐batch culture of hybridoma cells with control of glucose and glutamine concentrations
Authors: Kurokawa Hideo , Park Yong Soo , Iijima Shinji , Kobayashi Takeshi 
Published: December 2004

AbstractAn online system using HPLC was developed for the measurement of glucose, glutamine, and lactate in a culture broth. Using the system, the glucose and glutamine concentrations were controlled simultaneously by an adaptive‐control algorithm within the ranges of 0.2 to 2.0 and 0.1 to 0.6 g/L, respectively. When the glucose concentration was controlled at the low level of 0.2 g/L, the intracellular lactate dehydrogenase activity decreased by one‐half and the lactate concentration by one‐third, whereas the uptake rates of serine and glycine were about twice as high, compared with the amounts when the glucose concentration was controlled at 1.0 g/L. On the other hand, ammonia production increased when the glucose concentration was kept low. To reduce the production of inhibitory metabolites such as ammonia and lactate and improve the antibody production rate in a hybridoma cell culture, the concentrations of glucose and glutamine were controlled at 0.2 and 0.1 g/L, respectively. With these low concentrations of glucose and glutamine, the cell concentration (4.1 × 106 cells/mL) and antibody production (172 mg/L) both increased about twofold compared with the amounts when the glucose was controlled at higher levels. From these results, simultaneous control of the glucose and glutamine concentrations was shown to be useful in the production of antibody by hybridoma cell cultivation. © 1994 John Wiley & Sons, Inc.
Degradation of pencillin‐V in fermentation media
Authors: Christensen Lars H. , Nielsen Jens , Villadsen John 
Published: December 2004

AbstractIn Industrial production of penicillin there is a noticeable loss of the product through degradation reactions. It is shown that the degradation of penicillin‐V, both in a complex and in a chemically defined medium, can be separated into a phosphate‐catalyzed conversion of penicillin‐V to penicilloic‐V acid, overlaid by at least one other reaction in which penicillin V is degraded to as yet unknown products. Parameter values for the phosphatecatalyzed degradation are found to be independent of the type of fermentation medium. The rate of formation of other degradation products of penicillin‐V is found to be significantly higher in a complex fermentation medium with corn‐steep liquor in a chemically defined medium. © 1994 John Wiley & Sons, Inc.
Heterogeneity of biofilms in rotating annular reactors: Occurrence, structure, and consequences
Authors: Gjaltema A. , Arts P. A. M. , van Loosdrecht M. C. M. , Kuenen J. G. , Heijnen J. J. 
Published: December 2004

AbstractA rotating annular reactor (Roto Torque) was used for qualitative and quantitative studied on biofilm heterogeneity. In contrast to the classic image of biofilms as smooth, homogeneous layers of biomass on a substratum, studies using various pure and mixed cultures consistently revealed more‐dimensional structures that resembled dunes and ridges, among others. These heterogeneities were categorized and their underlying causes analyzed. Contrary to expectations, motility of the microorganisms not a decisive factor in determining biofilm homogeneity. Small Variations in substratum geometry homogeneity. Small variations in substratum geometry and flow patterns were clearly reflected in the biofilm pattern. Nonhomogeneous flow and shear patterns in the reactor, together with inadequate mixing resulted in significant, position‐dependent differences in surface growth. It was therefore not possible to take representative samples of the attached biomass. Like many other types of reactors, the Roto Torque reactor is valuable for qualitative and morphological biofilm experiments but less suitable for quantitative physiological and kinetics studies using attached microorganisms. © 1994 John Wiley & Sons, Inc.
Flotation of cadmium‐loaded biomass
Authors: Matis K. A. , Zouboulis A. I. 
Published: December 2004

AbstractBiosorption of heavy metal ions such as Cd2+ by dead biomass has been recognized as a potential alternative to existing removal technologies applied to wastewater treatment. Two bacterial strains were studied in the laboratory, streptomyces griseus and S. clavuligerus, an industrial by‐product. Both washed and unwashed samples were examined. Foam flotation proposed in this work as the separation state following biosorption. Effective biomass separation was conducted in the presence of a frother, ethanol. The pH of the solution was a crucial parameter for flotation and also for metal binding. Other basic parameters of flotation examined were the initial cadmium concentration in the dilute aqueous solution and the quantity of biomass used. A study of ζ‐potential measurements of the actinomycetes was carried out under the conditions used in the separation; surface tension was also measured. These provided useful information on the process. © 1994 John Wiley & Sons, Inc.
A new method for studying microaerobic fermentations. II. An experimental investigation of xylose fermentation
Authors: Franzén Carl Johan , Lidén Gunnar , Niklasson Claes 
Published: December 2004

AbstractA new experimental technique, called oxygen programmed fermentation (OPF), was used to study microbial cultures of the years Pichia stipitis and Candida utilis growing on xylose as carbon and energy source. In the oxygen programmed fermentation, the inlet oxygen mole fraction was continuously changed to scan through a wide range of oxygen uptake rates in a continuous culture. The largest ethanol yields and productivities of P. stipitis were found at oxygen transfer rates below 1.5 mmol L−1 h−1. It was found that the ratio between the culture fluorescence and near‐IR absorbance increased at oxygen transfer rates lower than 1.5 mmol L−1 h−1. Small amounts of ethanol were produced also by C. utilis when the oxygen transfer rate was between 0 and 3 mmol L−1 h−1. It is suggested that OPF will form a nice complement to ordinary, microaerobic chemostat experiments, by making the identification of interesting regions of oxygen transfer rates possible in an efficient and time‐saving initial experiment. © 1994 John Wiley & Sons, Inc.
Feasibility of expanded granular sludge bed reactors for the anaerobic treatment of low‐strength soluble wastewaters
Authors: Kato Mario T. , Field Jim A. , Versteeg Paul , Lettinga Gatze 
Published: December 2004

AbstractThe application of the expanded granular sludge bed (EGSB) reactor for the anaerobic treatment of low‐strength soluble wastewaters using ethanol as a model substrate was investigated in laboratory‐scale reactors at 30oC. Chemical oxygen demand (COD) removal efficiency was above 80% at organic loading rates up to12 g COD/L · d with influent concentrations as low as 100 to 200 mg COD/L. These results demonstrate the suitability of the EGBS reactor for the anaerobic treatment of low‐strength wastewaters. The high treatment performance can be attributed to the intense mixing regime obtained by high hydraulic and organic loads. Good mixing of the bulk liquid phase for the substrate‐biomass contact and adequate expansion of the substrate‐biomass contact and adequate expansion of the sludge bed for the degassing were obtained when the liquid upflow velocity (Vup) was greater than 2.5 m/h. Under such conditions, an extremely low apparent Ks value for acetoclastic methanogenesis of 9.8 mg COD/L was observed. The presence of dissolved oxygen in the wastewater had no detrimental effect on the treatment performance. Sludge piston flotation from pockets of biogas accumulating under the sludge bed occurred at Vup lower than 2.5 m/h due to poor bed expansion. This problem is expected only in small diameter laboratory‐scale reactors. A. more important restriction of the EGSB reactor was the sludge washout occurring at Vup higher than 5.5 m/h and which was intensified at organic loads higher than 7 g COD/L· d due to buoyancy forces from the gas production. To achieve an equilibrium between the mixing intensity and the sludge hold‐up, the operation should be limited to an organic loading rate of 7 g COD/L d· and to a liquid up‐flow velocity between 2.5 and 5.5 m/h © 1994 John Wiley & Sons, Inc.
Enzymatic hydrolysis of whey proteins. II. Molecular‐weight range
Authors: Tello P. González‐ , Camacho F. , Jurado E. , Páez M. P. , Guadix E. M. 
Published: December 2004

AbstractUsing high‐pressure liquid chromatography we studied the distribution of molecular weights in whey‐protein hydrolysates using the following commercially obtained proteases: Alcalasa 0.6 L and Protease 660 L, both bacterial in origin, and PEM 2500 S, of animal origin. In each of the systems, the range of molecular weights in the hydrolysate depended solely on the degree of hydrolysis (DH) achieved. For DH ≥ 20, between 65% and 95% of the hydrolysate is made up of peptides with a molecular weight of less than 1,000 Da. © 1994 John Wiley & Sons, Inc.
Interactions between benzene, toluene, and p‐xylene (BTX) during their biodegradation
Authors: Oh Young‐Sook , Shareefdeen Zarook , Baltzis Basil C. , Bartha Richard 
Published: December 2004

AbstractA microbial consortium and Pseudomonas strain (PPO1) were used in studying biodegradation of benzene, toluene, and p‐xylene under aeorbic conditions. Studies involved removal of each compound individually as well as in mixture with the others. Both cultures exhibited a qualitatively similar behavior toward each compound. Both the pure culture and the consortium grew on benzene following Monod kinetics, on toluene following inhibitory (Andrews) kinetics, whereas neither could grow on P‐xylene. Benzene and toluene mixtures were removed under cross‐inhibitory (competitive inhibition) kinetics. In the presence of benzene and/or toluene, p‐xylene was cometabolically utilized by both cultures, but was not completely mineralized. Metabolic intermediates of p‐xylene accumulated in the medium and were identified. Benzene and toluene were completely mineralized. Cometabolic removal of p‐xylene reduced the yields on both benzene and toluene. Except for cometabolism, kinetic constants were determined from data analysis and are compared with values published recently by other researchers. © 1994 John Wiley & Sons, Inc.
Liquid flow in heterogeneous biofilms
Authors: de Beer Dirk , Stoodley Paul , Lewandowski Zbigniew 
Published: December 2004

AbstractLiquid flow was studied in aerobic biofilms, consisting of microbial cell clusters (discrete aggregates of densely packed cells) and interstitial voids. Fluorescein microinjection was used as a qualitative technique to determine the presence of flow in cell clusters and voids. Flow velocity profiles were determined by tracking fluorescent latex spheres using confocal microscopy. Liquid was flowing through the voids and was stagnant in the cell clusters. Consequently, in voids both diffusion and convection may contribute to mass transfer, whereas in cell clusters diffusion is the dominant factor. The flow velocity in the biofilm depended on the average flow velocity of the bulk liquid. The velocity profiles in biofilms were linear and the velocity was zero at the substratum surface. The velocity gradients within biofilms were 50% of that near walls without biofilm coverage. The influence of the biofilm roughness on the flow velocity profiles was similar to that caused by rigid roughness elements. © 1994 John Wiley & Sons, Inc.
A practical approach to biosurfactant production using nonaseptic fermentation of mixed cultures
Authors: Ghurye G. L. , Vipulanandan C. , Willson R. C. 
Published: December 2004

AbstractNon‐aseptic production of biosurfactant from molasses by a mixed culture was investigated in stirred batch reactors. Biosurfactant production was quantified by surface tension reduction, critical micelle dilution (CMD), and emulsification capacity (EC). Biosurfactant production was directly correlated with biomass production, and was improved by pH control and addition of yeast extract. Centrifugation of the whole broth increased emulsifying capacity and reduced surface tension. Acidification of the whole broth increased the emulsification capacity but reduced the apparent biosurfactant concentration (CMD), without affecting the surface tension. The emulsification capacity of the cell‐free broth was equivalent to that of a 100 mg/L solution of sodium dodecyl sulfate. The emulsification capacity of the whole broth and cell‐free broth were reduced by about 50% at and above NaCl concentrations of 100mM. Preliminary characterization suggests that the biosurfactant activity is primarily associated with one or more protease‐sensitive species, released from cells in larger quantities after more vigorous centrifugation. © 1994 John Wiley & Sons, Inc.
Kinetics of growth and elemental sulfur oxidation in batch culture of thiobacillus ferrooxidans
Authors: Konishi Yasuhiro , Takasaka Yuichiro , Asai Satoru 
Published: December 2004

AbstractThe kinetics of oxidation of elemental sulfur by Thiobacillus ferrooxidans in a batch reactor was followed by measuring the concentration of adsorbed cells on the sulfur surface, the concentration of free cells in liquid medium, and the amount of sulfur oxidized. As the elemental sulfur was oxidized to sulfate, the liquid‐phase concentration of free cells continued to increase with time, whereas the surface concentration of adsorbed cells per unit weight of sulfur approached a limiting value, i.e., the maximum adsorption capacity. During sulfur oxidation, there was a close correlation between the concentrations of adsorbed and free cells, and these data were well correlated with the Langmuir isotherm. The observed rates of batch growth and sulfur oxidation were consistent with a kinetic model, assuming that the growth rate of batch growth and sulfur oxidation were consistent with a kinetic model. Assuming that the growth rate of adsorbed bacteria is proportional to the product of the concentration of adsorbed cells and the fraction of adsorption sites unoccupied by cells. The kinetic and stoichiometric parameters appearing in the model were evaluated using the experimental data and were compared with parameters determined previously for a few metal sulfides. © 1994 John Wiley & Sons, Inc.
Modeling and optimization of the baculovirus expression vector system in batch suspension culture
Authors: Power John F. , Reid Steven , Radford Kathryn M. , Greenfield Paul F. , Nielsen Lars K. 
Published: December 2004

AbstractA mathematical model has been developed that predicts the cell population dynamics and production of recombinant protein and infective extracellular virus progeny by insect cells after infection with baculovirus in batch suspension culture. Infection in the model is based on the rate of virus attachment to suspended insect cells under culture conditions. The model links the events following infection with the sequence of gene expression in the baculovirus replicative cycle. Substrate depletion is used to account for the decrease in product yield observed when infecting at high cell densities. Model parameters were determined in shaker flasks for two media: serum‐supplemented IPL‐41 medium and serum free Sf900II medium. There was good agreement between model predictions and the results from an independent series of experiments performed to validate the mode. The model predicted: (1) the optimal time of infection at high multiplicity of infection: (2) the timing and magnitude of recombinant protein production in a 2‐L bioreactor; and (3) the timing and magnitude of recombinant protein production at multiplicities of infection from 0.01 to 100 plaque‐forming units per cell. Through its ability to predict optimal infection strategies in batch suspension culture, the model has use in the design and optimization of large‐scale systems for the production of recombinant products using the baculovirus expression vector system. © 1994 John Wiley & Sons, Inc.
Effects of substrate branching characteristics on kinetics of enzymatic depolymerizaion of mixed linear and branched polysaccharides: I. Amylose/amylopectin α‐amylolysis
Authors: Park Jun T. , Rollings James E. 
Published: December 2004

AbstractHydrolysis reactions of homopolysaccharides, which differ in their degree of branching, and mixtures of linear and branched polymers were carried out with α‐amylase. The branching structures of both the original amylopectin substrate and the cluster domains of amylopectin, obtained by ethanol precipitation of the products of the action of α‐amylase, were characterized via enzymatic digestion with debranching enzyme (i.e., isoamylase), followed by the fractions of the resulting products using gel filtration chromatography. The structural properties (i.e., molecular weight, molecular weight distribution, and branching characteristics) of the resulting products during depolymerization of amylose, amylopectin and their mixtures via α‐amylase were characterized by size exclusion chromatography coupled with a low angle laser right scattering (SEC/LALLS) technique. It was determined that substrate branching characteristics strongly influence both the observed enzymatic activity as well as the enzyme's action pattern. A simplified kinetic model that represents the hydrolysis reactions of amylose and amylopectin mixtures via endo‐acting α‐amylase is proposed. We found that that reaction kinetics (i.e., enzyme affinity) was also governed by the substrate's conformation in solution. The relationships between the mass fraction of branched polymers and the kinetic parameters during α‐amylolysis were compared with those predicted by the kinetic model. Excellent agreement was found between the model predictions and the experimental observations. The results reported here imply and interrelationship between enzyme action and polymeric substrate structural properties. © 1994 John Wiley & Sons, Inc.