bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new isolation and purification method for staphylococcal protein A using membrane encapsulated rabbit IgG‐agarose
Authors: Sakoda Akiyoshi , Wang Henry Y. 
Published: December 2004

AbstractA new isolation and purification method for bioproducts using membrane‐encapsulated affinity adsorbents was investigated. The new method involves encapsulation of affinity adsorbents, batch adsorption of the bioproduct from whole fermentation broth and rapid batch desorption after dissolution of the capsule membranes. Recovery of protein A from Staphylococcus aureus was used as the model experimental system. Affinity adsorbents such as rabbit IgG‐agarose were successfully encapsulated within calcium alginate membranes and used directly to recover protein A from whole cell homogenate containing a number of macromolecular contaminants as well as suspended solids. Both high yield and high purity of protein A were recovered by this method in comparison with various previously reported methods.
Measurement of KLa by a gassing‐in method with oxygen‐enriched air
Authors: Chang Ho Nam , Halard Benoit , Moo‐Young Murray 
Published: December 2004

AbstractThe dynamic gassing‐out method using nitrogen for gas–liquid KLa measurements has been modified so that gassing‐out is performed with air and gassing‐in with oxygen‐enriched air. This new method was proven theoretically valid for use in inert model systems and in actual fermentation systems. The KLa values were measured in a 1‐m‐high bubble column and compared with those obtained from the traditional gassing‐in method for three different mixing models in batchwise contacting: mixed gas and liquid (MMB); plug‐flow gas and mixed liquid (PMB); and plug‐flow gas and plug‐flow liquid (PPB). The KLa values obtained from the new method were consistent with those of the method of Bartholomew et al. Discrimination between the models appeared to be not important for the 1‐m‐high column, but the theoretical analysis revealed that it would become necessary for columns about 10 m and higher.
Culture of photomixotrophic soybean and pine in a modified fermentor using a novel impeller
Authors: Treat W. J. , Engler C. R. , Soltes E. J. 
Published: December 2004

AbstractPhotomixotrophic suspensions of Glycine max (soybean) and Pinus elliottii (slash pine) have been successfully cultured in a hybrid stirred tank photobioreactor using a novel cell‐lift impeller. A cell‐lift impeller exhibited cell viabilities over 90% and an average cell aggregate size of 1.0 mm or less. Flat‐bladed turbines produced equivalent biomass to the cell‐lift impeller, but cell viability was reduced (85%) and cell aggregate size increased (3–5 mm diameter). Maximum fresh weights of 82 g L−1 (soybean) and 52 g L−1 (slash pine) were achieved in 15 days using continuous lighting (90–100 μE m−2 s−1) and supplemental 2% CO2 inlet gas. Maximum biomass was achieved using an impeller speed of 60 rpm with air‐flow rate of 0.2 vvm for the cell‐lift impeller and the pair of flat bladed turbines. The lag and early exponential phases were characterized by (1) rapid hydrolysis of sucrose followed by preferential use of glucose and (2) a reduction in chlorophyll levels. Carbon dioxide (2%–5%) was an essential nutrient for photomixotrophic cell culture in the bioreactors.
Influence of dilution rate on the acidogenic phase products distribution during two‐phase lactose anaerobiosis
Authors: Kisaalita W. S. , Lo K. V. , Pinder K. L. 
Published: December 2004

AbstractAcidogenic fermentation of lactose was carried out in a continuous stirred reactor with a mixed anaerobic culture. From the variation of the reactor products with pH and dilution rate two possible carbon flow schemes were proposed for the reaction. In both schemes the carbon flow from pyruvate to butyrate and lactate was assumed to occur in parallel. A change in gas composition and in product concentrations at dilution rates between 0.1 and 0.15 h−1 for pH levels between 4.5 and 6.0 was ascribed to a shift in microbial population. To clarify the mechanism radiotracer tests were made using [U–14C]‐butyrate, [2–14C]‐propionate and [U–14C]‐lactate to determine the path of carbon flow during acidogenesis of lactose using a mixed culture. At a dilution rate between 0.1 and 0.15 h−1 and pH from 4.5 to 6.0 a rise in the lactate concentration in the product was shown to be due to a microbial population shift which disabled the conversion of lactate to other intermediary metabolites. It was also found that the flow of carbon from pyruvate to butyrate and lactate occurred by parallel pathways. Also, in the presence of hydrogen reducing methanogens, lactate was almost completely converted to acetate and not propionate. Butyrate was found to be converted to acetate at a slow rate as long as hydrogen reducing methanogens were present. The role played by propionibacteria in this lactose acidogenic eocosystem was minor. From the carbon flow model it can be concluded that lactate is the most suitable marker for optimizing an acidogenic reactor in a two‐phase biomethanation process.
Fast inferential adaptive optimization of a continuous yeast culture based on carbon dioxide evolution rate
Authors: Chang Yong K. , Lim Henry C. 
Published: December 2004

AbstractA fast inferential, multivariable adaptive optimization algorithm based on a fast responding off‐gas data, the carbon dioxide evolution rate (CER), has been developed and applied to a continuous baker's yeast culture to maximize the cellular productivity in simulation and experimental studies. In the simulation study the process was optimized based on CER measurements using readily available steady‐state data on the ratio between the cellular productivity and the CER. It was shown that the algorithm is two to three times faster than the algorithm based on cell mass concentration measurements. In the experimental study the CER was maximized without any information on the relationship between the cellular productivity and the CER. It took about 40 h for the process to converge, while about 80 h was required when the optimization was based on cell mass measurements. The attained steady state was found to be different but fairly close to that obtained with cell measurements. Briefly discussed is a switching to the cell‐mass‐based algorithm at the final stage of the optimization to overcome a potential inaccuracy.
Optimization of sulphur production in a biotechnological sulphide‐removing reactor
Authors: Buisman Cees J. N. , Geraats Bert G. , Ijspeert Peter , Lettinga Gatze 
Published: December 2004

AbstractA new biotechnological process for sulphide removal is proposed. The principle of this process is that sulphide is converted into elemental sulphur, which can be removed by sedimentation. In this article, investigations on the optimization of the sulphur production are reported. It seems that less than 10% sulphate is produced at low oxygen concentration, when the sulphide concentration in the reactor exceeds 10 mg/L. At sulphide concentrations higher than 20 mg/L only 5% of the incoming sulphide is converted to sulphate even at high oxygen concentrations. An immobilized biomass on recticulated polyurethane produced more sulphate than a free cell suspension at the same oxygen and sulphide concentration.
A mathematical model for examining growth and sporulation processes of Bacillus subtilis
Authors: Jeong J. W. , Snay J. , Ataai M. M. 
Published: December 2004

AbstractA mathematical model for the growth process of the bacterium Bacillus subtilis is described. The model is a highly structured one. The driving motivation for development of the model and explicit accounting of major interactions of metabolic networks in the model is related to our eventual goal that the model will be used in the analysis of complex biological patterns. Bacillus subtilis was chosen in our study due to the interesting sporulation process that these cells undergo in response to adverse environmental conditions including nutrient limitation. Sporulation process in B. subtilis represents a primordial prototype of cellular differentiation in higher cellular systems. Thus a model for the B. subtilis growth process should prove extremely useful for understanding questions of developmental biology. The model is capable of simulating the transition between the exponential and stationary phase of growth in a batch culture. Since during the transition period the growth process and the metabolism become decoupled and many transient processes are taking place, such predictions are a severe test for the validity of any model. A strategy to examine the leading hypothesis on B. subtills sporulation implementing GTP as a component which signals sporulation initiation is described.
A general model for aerobic yeast growth: Batch growth
Authors: Barford J. P. 
Published: December 2004

AbstractA general model for aerobic yeast growth in batch culture is presented. It is based on the concept that the aerobic metabolism of all yeasts is determined by the relative sizes of the transport rate of sugar into the cell and the transport rate of respiratory intermediates into the mitochondrion. If the rate of sugar uptake rate exceeds the rate of transport of respiratory intermediates into the mitochondrion (as in Saccharomyces cerevisiae, S. uvarum, and S. pombe), the metabolism exhibits the features of ethanol excretion and limited specific oxygen uptake rate. If the rate of transport of respiratory intermediates into the mitochondrion is of the same order as the transport of sugar into the cell (as in Candida utilis), the metabolism is characterized by little or no ethanol excretion and a much higher specific oxygen uptake rate. Batch data from an extensive range of yeast and carbon sources is used to illustrate the use of this model. The ability of this model to fit such an extensive range of experimental data suggests that it can be used as a generalized model for aerobic yeast growth.
A general model for aerobic yeast growth: Continuous culture
Authors: Barford J. P. 
Published: December 2004

AbstractA general model for the aerobic growth of yeast in continuous culture is presented. The model is capable of simulating the complete range of metabolic responses observed for yeast growth in continuous culture including respiratory repression, saturated respiratory capacity, and respiratory depression.It is postulated that respiratory depression is the result of the adaptation (increase in capacity of the respiratory intermediate transport proteins located at the mitochondrial membrane). Respiratory repression and subsequent saturated respiratory capacity is postulated to be the result of the gradual transfer of biosynthetic intermediates provision from the mitochondrion to the cytoplasm or, possibly, the adaptation (increase) in the capacity of the cell to excrete ethnol. It is difficult to provide a definitive experimental verification of these postulates.Irrespective of the biochemical basis of respiratory repression and depression, the model described is capable of simulating the complete range of metabolic responses obtained for yeast growth in continuous culture. It is the only model reported in the literature capable of achieving this.
Use of an oxygen microsensor for the determination of intrinsic kinetic parameters of an immobilized oxygen reducing enzyme
Authors: Hooijmans C. M. , Geraats S. G. M. , Luyben K. Ch. A. M. 
Published: December 2004

AbstractAn oxygen microsensor was used to measure internal oxygen profiles in biocatalyst particles of different diameter and activity. The particles were made of agarose gel and contained an oxygen reducing enzyme, L‐lactate mono‐oxygenase. The kinetics of the enzyme could be well described by the Michaelis–Menten equation. From the internal substrate concentration profile the intrinsic kinetic parameters were determined by means of fitting a simulated profile to the measurements, using Marquardt's algorithm. The intrinsic kinetic parameters found following this procedure appeared to be independent of particle radius or enzyme loading used, proving the method to be reliable. These parameters were also compared with the kinetic parameters of the free enzyme which were determined in a biological oxygen monitoring system. The intrinsic kinetic parameters showed a decrease with a factor 2.3 for Vm value and with a factor 2.7 for the Km value compared to the parameters for the free enzyme. From this the conclusion can be drawn that the immobilization as such or the carrier material not only can have an effect on the maximum intrinsic conversion rate (Vm) but also on the affinity of the enzyme (Km) for oxygen.
Development of a strategy to control the dissolved concentrations of oxygen and carbon dioxide at constant shear in a plant cell bioreactor
Authors: Smith Jeffrey M. , Davison Stowell W. , Payne Gregory F. 
Published: December 2004

AbstractTo examine the effects of volatile components on plant cell growth, a bioreactor control system was developed to simultaneously control the dissolved concentrations of both oxygen and carbon dioxide. The first step in this work was to develop a mathematical model to account for gas–liquid mass transfer; biological utilization and production of O2 and CO2; and the series of chemical reactions of CO2 in water. Using this model and dynamic measurements for dissolved O2 and CO2, it was observed that (1) both absorption and desorption of a volatile component could be described by a single mass transfer coefficient, Kla, and (2) Kla values for oxygen and carbon dioxide transfer were directly proportional. The second step of this work was to employ the mathematical model in an adaptive feed‐forward strategy to control the dissolved O2 and CO2 concentrations by manipulating the inlet gas composition to the bioreactor. This strategy allowed dissolved concentrations to be controlled without the need for changing either the total gas flow rate or agitator speed. Adaptive control was required because the volumetric rates of O2 and CO2 consumption and production vary with time during long term operation and therefore these rates must be continually updated. As the final step, we demonstrated that this control strategy was capable of controlling the dissolved gas concentrations in both short‐ and long‐term studies involving the cultivation of Catharanthus roseus plant cells.
Degradation kinetics of pentachlorophenol byPhanerochaete chrysosporium
Authors: Lin Jian‐Er , Wang Henry Y. , Hickey Robert F. 
Published: December 2004

AbstractThe extracellular enzymes and cell mass from the pregrownPhanerochaete chrysosporiumcultures were used for the degradation of PCP. The use of both extracellular enzymes and cell mass resulted in extensive mineralization of PCP, while the action of only the crude extracellular enzymes led to the formation of a degradation intermediate (TCHD). A kinetic model, which describes the relationship among PCP degradation, initial PCP concentration, dosage of extracellular enzymes, and cell mass concentration, was developed. Based on this model, various effects of initial PCP concentration, dosage of extracellular enzymes, and cell mass concentration were evaluated experimentally. It was found that when initial PCP concentration is lower than 12 μmol/L, the model of a parallel‐series first‐order reaction is sufficient to describe the degradation process. PCP disappearance and mineralization were enhanced by increasing either the extracellular enzyme concentration or the cell mass concentration. As high as 70% of PCP mineralization could be obtained by using a higher dosage of extracellular enzymes and cell mass. Various parameters of the kinetic model were determined and the model was verified experimentally. Simulation using this model provided the criteria needed to choose rational dosages of extracellular enzymes and cell mass for the degradation of PCP. Data reported allow some insight into the function of the extracellular enzymes and cell mass ofP. chrysosporiumin degradation processes of toxic pollutants and assist in the design and evaluation of practical bioremediation methods.
Increased mass transfer to microorganisms with fluid motion
Authors: Logan Bruce E. , Dettmer James W. 
Published: December 2004

AbstractThe effect of fluid flow and laminar shear on bacterial uptake was examined under conditions representative of the fluid environment of unattached and attached cells in wastewater treatment bioreactors. Laminar shear rates below 50 s−1 did not increase leucine uptake by suspended cultures of Zoogloea ramigera. However, leucine uptake by cells fixed in a flow field of ∼ 1 mm s−1 was 55–65% greater than uptake by suspended cells. Enhanced microbial uptake with advective motion is consistent with mass transfer rates calculated using Sherwood number correlations. Advective flow increases microbial uptake by increasing collisions between substrate molecules and cells through compression of the concentration boundary layer surrounding a cell. The rate of leucine uptake suggests that binding proteins used to transport leucine into the cell can occupy approximately 1% of the cell surface area.
Oxidation of hydrogen sulfide by Thiobacilli
Authors: Cadenhead Patricia , Sublette Kerry L. 
Published: December 2004

AbstractIt has been previously demonstrated that the chemoautotroph and facultative anaerobe, Thiobacillus denitrificans, may be cultured aerobically or anaerobically in batch and continuous reactors on H2S(g) under sulfide‐limiting conditions. A process has been proposed for the removal of H2S from gases based on oxidation of H2S by T. denitrificans. Described here is a study of H2S oxidation by other Thiobacilli, the purpose of which has been to determine whether other Thiobacilli offer any advantages over T. denitrificans in the aerobic oxidation of H2S. Although four other species of Thiobacillus were found to grow on H2S as an energy source, none offer a clear advantage over T. denitrificans.
Air‐bubbling, hollow‐fiber reactor with cell bleeding and cross‐flow filtration
Authors: Nishii Kunio , Sode Koji , Karube Isao 
Published: December 2004

AbstractContinuous asymmetric reduction of dyhydrooxoisophorone (DOIP) to 4‐hydroxy‐2,2,6‐trimethylcyclo‐hexanone (4‐HTMCH) was achieved by a thermophilic bacterium Bacillus stearothermophilus NK86‐0151. Three reactors were used: an air‐bubbling hollow‐fiber reactor with cell bleeding and cross‐flow filtration, an air‐lift reactor, and a CSTR with PAA immobilized cells. The maximum cell concentration of 11.1 g dry wt L−1 was obtained in an air‐bubbling hollow‐fiber reactor, while in the other reactors the cell densities were between 3.5 and 4.1 g dry wt L−1 The optimum bleed ratio was 0.1 at the dilution rate 0.3 h−1 in the hollow‐fiber reactor. The highest viable cell concentration was maintained in the dilution range of 0.4–0.7 h−1 by a combination of proper cell bleeding and cross‐flow filtration. The maximum volumetric productivity of 4‐HTMCH reached 826 mg L−1 h−1 at the dilution rate 0.54 h−1. This value was 4 and 2 times higher than those in the air‐lift reactor and CSTR, respectively. The increasing viable cell concentration increased the volumetric productivity of 4‐HTMCH. A cell free product solution was continuously obtained by cross‐flow filtration.
Sorbitol production in charged membrane bioreactor with coenzyme regeneration system: I. Selective retainment of NADP(H) in a continuous reaction
Authors: Ikemi Masahisa , Koizumi Noriaki , Ishimatsu Yoshiaki 
Published: December 2004

AbstractThe concept of a charged membrane bioreactor (CMBR) has been proposed for continuous reactions of enzymatic reduction dependent upon the nicotinamide coenzyme NADP(H). It was found that a composite membrane with a negative charge, NTR 7410, could retain NADP(H) selectively without any chemical modification. Several permeation experiments have revealed that the retainment of a coenzyme is based on electrostatic repulsion of negative charges between the membrane and the phosphate moiety of NADP(H). The retainment ratio was reduced by the addition of inorganic salt, although it could be restored to 0.8 in the presence of albumin. A reactor equipped with a charged membrane as the coenzyme separator module was constructed and used in the continuous production of sorbitol. NADPH‐dependent aldose reductase isolated from Candida tropicalis IAM 12202 was used for the production of sorbitol from glucose. The coenzyme oxidized in this reaction was enzymatically regenerated by conjugation with glucose dehydrogenase, together with the coproduction of gluconic acid from glucose. With a substrate conversion of 85%, 100 g/L sorbitol was produced and equimolar gluconic acid was coproduced for more than 800 h, indicating that the reaction was efficiently coupled to the enzymatic regeneration. The initial high retainment ratio of the membrane was almost maintained throughout the entire reaction. Consequently, the turnover number of the coenzyme reached 106,000.
Production of dextransucrase and dextran by Leuconostoc mesenteroides immobilized in calcium‐alginate beads: II. Semicontinuous fed‐batch fermentations
Authors: El‐Sayed Abdel‐Halim M. M. , Mahmoud Wafaa M. , Coughlin Robert W. 
Published: December 2004

AbstractCells of Leuconostoc mesenteroides immobilized in calcium alginate beads were used to produce dextransucrase (DS) in three sequential cycles of semicontinuous fed‐batch fermentations. Each cycle consisted of a fed‐batch DS production period of 24 h followed by a batch dextran production period for another 24 h. Free, suspended cells were used in only one cycle of fed‐batch DS production followed by a dextran production period. It was impractically tedious to separate and reuse free cells. Increasing sucrose feed rate from 5 to 10 g/L h led to increases of the total enzymatic activity by about 88% with immobilized cells and by about 100% with free cells. In DS fed‐batch semicontinuous fermentation, total enzymatic activity produced by immobilized cells was 1.35 and 1.56 times greater than that produced by free cells with respective sucrose feeding rates of 10 and 5 g/L h. These increases in enzyme productivity with immobilized cells, however, required total overall operating times three times longer (three cycles) than with free cells (one cycle). Growing the microorganism at optimum conditions for DS production also increased the dextran yield and shortened the time of conversion of sucrose to dextran, regardless of whether the cells were free or immobilized. Moreover, during three cycles of semicontinuous operation (144 h) immobilized cells produced more than three times as much dextran as free cells during one cycle (24 h).
The separation of affinity flocculated yeast cell debris using a pilot‐plant scroll decanter centrifuge
Authors: Bentham A. C. , Bonnerjea J. , Orsborn C. B. , Ward P. N. , Hoare M. 
Published: December 2004

AbstractThe use of a scroll decanter centrifuge for the removal and dewatering of affinity‐flocculated yeast cell debris from a crude homogenate is described. Laboratory shear modulus measurements were used to compare the structure of flocculated and nonflocculated sediments and to indicate the dewatering conditions under which the sediment could be discharged from the centrifuge. The structure of the flocculated sediment was such that a dry beach could be used within the centrifuge while still being able to discharge the solids. The scroll decanter performance for recovery and dewatering of the flocculated homogenate was found to be independent of feed flow rate and differential scroll rate. Eighty‐five percent of the solid material was recovered from the flocculated homogenate while the extent of sediment dewatering resulted in the loss of only 7% of the soluble protein in the sediment. The supernatant clarity matched that achieved by low‐gravity laboratory centrifugation studies.