bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integrated Ozonation‐Biotreatment of Pulp Bleaching Effluents Containing Chlorinated Phenolic Compounds
Authors: Heinzle E. , Geiger F. , Fahmy M. , Kut O. M. 
Published: March 2005

AbstractBleaching effluents from pulp and paper industry are problematic because they contain toxic chlorinated phenolic compounds and recalcitrant chlorinated lignin fragments of higher molecular weight. The chlorinated phenolic compounds have been shown to be rather easily removable in fluidized bed bioreactors. The total amount of adsorbable organic halogens (AOX), however, was only reduced by 20%‐30%. It is generally possible to oxidize all unsaturated organic compounds in the bleaching effluents by ozonation. However, ozone is still too expensive to allow complete treatment. Nevertheless, the increase of biodegradability of recalcitrant components by dechlorination and degradation of high molecular weight fractions by ozone can lead to increased efficiency in a subsequent biotreatment. In this study the simple ozonation of bleaching effluents with and without biological pretreatment was compared with sequential or cyclic ozonation—biotreatment schemes. By integrated ozonation—biotreatment, the degradation efficiency relative to the amount of ozone consumed was markedly increased. The overall efficiency of the treatment process in terms of fractional removals of global parameters COD, TOC, and AOX increased. More than 70% of AOX were eliminated. No toxic effect was observed in the cyclic reactor, where the liquid passed was cycling between an ozonation and a biotreatment zone. In the liquid phase no dissolved ozone could be detected in this reactor.
An Improved Method for Disruption of Microbial Cells with Pressurized Carbon Dioxide
Authors: Lin Ho‐Mu , Yang Zhiying , Chen Li‐Fu 
Published: March 2005

AbstractDisruption of microbial cells by pressurized carbon dioxide at both subcritical and supercritical temperatures has been previously investigated. This method differs in principle from other disruption techniques and was found to have potential applications for rupture of a variety of microorganisms. However, it is not as effective for some of the microbial cells, including yeast, of which the cell walls are extremely robust and rigid. This work suggests an alternative operation to improve the disruption rates of cells by repeatedly releasing the applied fluid pressure within the cells in the midst of a disruption process. The improvement is substantial at all the experimental conditions studied.
Techniques for the Estimation of Cell Concentration in the Presence of Suspended Solids
Authors: Kennedy M. J. , Thakur M. S. , Wang D. I. C. , Stephanopoulos Gregory N. 
Published: March 2005

AbstractMeasuring cell concentration is of fundamental importance in many biochemical processes. However, this measurement is very difficult to make when solid particles are present along with the cells. This review examines strategies that have been used to estimate cell concentration in the presence of solid particles.
Recovery of Propionic and Acetic Acids from Fermentation Broth by Electrodialysis
Authors: Weier Anthony J. , Glatz Bonita A. , Glatz Charles E. 
Published: March 2005

AbstractAcetic and propionic acids can be produced by fermentation. In this process, acid recovery is important both for producing a concentrated product from the broth and for removing acid from the broth to reduce product inhibition during the fermentation. The purpose of this work was to characterize the performance of an electrodialysis unit for carrying out both tasks. Current efficiencies, water transport, and product concentrations were determined both for model solutions of the acids and for fermentation broths to determine the limiting factors in using this separation method. In addition, observations were made of fouling behavior of the membranes in this use. The highest concentrations of product were obtained by contacting with the most concentrated feed and doing so in the absence of competing ions. For the range studied here, a maximum concentration of 13.8% (w/v) sodium propionate was obtained. In the batch recycle mode, final concentrations in the concentrate were reduced, but acid recoveries were improved by the presence of other ions because the low‐current shut‐off was delayed. The use of electrodialysis for producing a concentrated acid product is not promising unless salt levels in the medium can be reduced and acid levels increased. However, electrodialysis can be used to maintain low acid levels in the fermentor during extractive fermentation.
The Use of Pressure to Modify Enzyme Activity in Reversed Micelles
Authors: Rao A. Madhusudhan , Kommareddi N. , John V. T. 
Published: March 2005

AbstractPressurization of enzyme‐containing AOT‐water‐isooctane reversed micelles with low molecular weight gases leads to markedly different responses in activity characteristics. Microbial lipases exhibit a total cutoff in activity with as low a pressure as 2 MPa and a remarkable activity regain with depressurization. The observation also holds for reaction in monophasic organic solvents. The protease, α‐chymotrypsin, is unaffected by pressurization until a critical pressure wherein micellar instability occurs. The use of pressure as a switch for lipase reaction in nonaqueous media is discussed.
Dextran Retention in the Rat Brain Following Release from a Polymer Implant
Authors: Dang Wenbin , Saltzman W. Mark 
Published: March 2005

AbstractIntracranial controlled release polymers may improve drug administration to the brain, where therapy is frequently limited due to the low permeability of brain capillaries to therapeutic agents. On the basis of drug transport and elimination rates, we proposed that high molecular weight, water‐soluble molecules would be retained in the brain space following release from an intracranial implant. To test this hypothesis, solid particles of different molecular weight fractions of fluorescein isothiocyanate labeled dextran (FITC‐dextran; 4 × 103 Da (4 kDa) < weight‐averaged molecular weight (Mw) < 150 kDa) or fluorescein were uniformly dispersed in matrices of a polyanhydride copolymer synthesized from a fatty acid dimer and sebacic acid in a 50:50 ratio, P(FAD: SA). When incubated in buffered saline, FITC‐dextran fractions of 70 kDa Mw were released from the polymer within 48 h; 4 kDa Mw FITC‐dextran and fluorescein were released more slowly. Following implantation of P(FAD:SA) matrices containing either 70 kDa Mw FITC‐dextran, 4 kDa Mw FITC‐dextran, or fluorescein into the brains of normal rats, fluorescent tracers were continuously released into the brain tissue for 30 days. Tracer concentrations within the brain were significantly higher for large molecular weight tracers (70 kDa Mw FITC‐dextran ≫ 4 kDa Mw FITC‐dextran > fluorescein). The rate of elimination, 𝔨app, of each tracer from the brain was determined by comparing experimental data with a model describing tracer diffusion/elimination in the brain extracellular space; 𝔨app decreased with increasing molecular weight (fluorescein > 4 kDa Mw FITC‐dextran > 70 kDa Mw FITC‐dextran).
Application of an On‐Line Turbidimeter for the Automation of Fed‐Batch Cultures
Authors: Yamane Tsuneo 
Published: March 2005

AbstractRecent advances in the technology of continuous in situ turbidity measurements in microbial cultivations are reviewed. Some characteristics of commercially available on‐line laser turbidimeters are estimated in relation to requirements of sensors for microbial cultures. A system for the automation of fed‐batch cultures using an on‐line turbidimeter is proposed. Experimental data are presented concerning fed‐batch cultures grown on synthetic and natural complex media. In situ turbidity data were found to be particularly useful for the automation of the feeding of natural complex nutrient solutions by converting the data into dry cell mass concentration and at the same time utilizing the instantaneous data on the culture broth volume through a computer.
Fermentation of Crystalline Cellulose to Ethanol by Klebsiella oxytoca Containing Chromosomally Integrated Zymomonas mobilis Genes
Authors: Doran Joy B. , Ingram L. O. 
Published: March 2005

AbstractComplete enzymatic hydrolysis of cellulose to glucose is generally required for efficient fermentation to ethanol. This hydrolysis requires endoglucanase, exoglucanase, and cellobiase. The Gram‐negative bacterium, Klebsiella oxytoca, contains the native ability to transport and metabolize cellobiose, minimizing the need for extracellular cellobiase. Strain P2 is a recombinant derivative in which the Zymomonas mobilis pdc and adhB genes have been integrated into the chromosome and expressed, directing the metabolism of pyruvate to ethanol. This organism has been evaluated in simultaneous sacchari‐fication and fermentation (SSF) experiments to determine optimal conditions and limits of performance. The temperature was varied between 32 and 40 °C over a pH range of 5.0–5.8 with 100 g/L crystalline cellulose (Sigmacell 50, Sigma Chemical Company, St. Louis, MO) as the substrate and commercial cellulase (Spezyme CE, South San Francisco, CA). A broad optimum for SSF was observed, with a pH of 5.2–5.5 and temperatures of 32–35 °C, which allowed the production of over 44 g of ethanol/L (81–86% of the maximum theoretical yield). Although the rate of ethanol production increased with cellulase, diminishing improvements were observed at enzyme loadings above 10 filter paper units/g of cellulose. Over 40 g of ethanol/L was produced with relatively low enzyme loadings: 7–10 filter paper units/g of cellulose. Two optimal SSF conditions were identified for fermentation yield with strain P2: pH 5.2 at 35 °C and pH 5.5 at 32 °C. Under these conditions, 47 g of ethanol/L was produced in 144 h (0.48 g of ethanol/g of cellulose). Maximal rates of ethanol production were observed at 37 °C and pH 5.0 and produced over 40 g of ethanol/L in 72 h (final yield of 0.432 g of ethanol/g of cellulose after 96 h). All fermentations except those conducted at 40 °C and low pH (pH 5.0–5.5) exceeded 70% of theoretical ethanol yields. Tight process controls may not be required using this organism since temperatures between 32 and 37 °C at pH ranges between 5.0 and 5.8 still produced good yields.
Comparison of Trypan Blue Dye Exclusion and Fluorometric Assays for Mammalian Cell Viability Determinations
Authors: Altman Steven A. , Randers Lisa , Rao Govind 
Published: March 2005

AbstractA hemocytometer‐based trypan blue dye exclusion cell quantitation and viability assay was compared with a similar assay using simultaneous fluorometric staining with fluorescein diacetate and propidium iodide. Viable and nonviable cell densities were measured, and culture viability was calculated both during the normal growth cycle of a murine hybridoma and in response to the application of millimolar concentrations of either tert‐butyl hydroperoxide or ferrous iron. During the early phase of rapid hybridoma cell growth, assay‐based differences in viable cell density were not significant. As the culture aged, the trypan blue dye exclusion assay significantly overestimated cell viability, thereby underestimating nonviable cell density and yielding an erroneous estimation of the overall viability of the culture. Because of its lack of ambiguity in the identification of stained, nonviable cells and its resulting increased accuracy in the estimation of culture viability, the fluorometric assay was considered a better choice for the evaluation of cell viability.
Gene Structural Analysis and Expression of Human Renal Dipeptidase
Authors: Satoh Susumu , Ohtsuka Kazuyuki , Keida Yuriko , Kusunoki Chihiro , Konta Yoshiyuki , Niwa Mineo , Kohsaka Masanobu 
Published: March 2005

AbstractHuman renal dipeptidase cDNA and genomic DNA were isolated from human kidney cDNA and genomic libraries, respectively. The human renal dipeptidase gene has a total length of approximately 6 kb and consists of ten exons and nine introns. The exons and cDNA each encode the 411 amino acid residues of the precursor protein, including 16 amino acid residues of signal sequence and a hydrophobic carboxyl terminal sequence for the attachment of a phosphatidylinositol glycan. Although the cDNA was slightly different from the cDNA reported by Adachi et al. (1990), the differences observed suggest, by comparison with human genomic DNA, that it may not represent an allelic variant but a cloning artifact. The recombinant human renal dipeptidase was produced on the surface of transfected L929 cells and had the same character as native renal dipeptidase. Northern blotting hybridization analysis showed that renal dipeptidase mRNA is only transcribed in kidney.
Production of Oryzacystatins I and II in Escherichia coli Using the Glutathione S‐Transferase Gene Fusion System
Authors: Michaud Dominique , Nguyen‐Quoc Binh , Yelle Serge 
Published: March 2005

AbstractIn recent years, several studies have demonstrated the potential of proteinase inhibitors for the biocontrol of insect pests. For such a control approach, however, strategies must be developed for the simple and efficient production of active inhibitors. In this study, oryzacystatins I (OCI) and II (OCII) were produced in Escherichia coli using the glutathione S‐transferase (GST) gene fusion system. Both inhibitors were produced in large amounts as fusion products (∼100 mg/L E. coli culture) and were apparently stable when accumulated in bacterial cells. Enzyme specificities and inhibition constants of the fusion proteins were similar to those determined for free inhibitors and those reported for naturally occurring inhibitors isolated from rice, preventing the necessity of using an expensive and time‐consuming cleavage step for the obtention of active OCs. The GST system thus appears appropriate for simple and efficient large‐scale production of the two cysteine proteinase inhibitors.
Stability of Producer Hybridoma Cell Lines after Cell Sorting: A Case Study
Authors: Kromenaker Sandra J. , Srienc Friedrich 
Published: March 2005

AbstractFlow cytometry was used in combination with immunofluorescent staining for intracellular and surface‐associated antibody contents to identify a significant nonproducer cell fraction in a murine hybridoma cell line that had shown a decline in monoclonal antibody productivity with passaging. Viable producer cells stained for surface‐associated antibody content were isolated by cell sorting on the basis of surface fluorescence intensity. The fraction of nonproducers was initially reduced from 85% to 20%. Sorting a second time, after these cells were cultivated for 2 weeks, further reduced the fraction of nonproducers to less than 4%. The stability of this purified producer hybridoma cell line during passaging and after a freeze‐thaw cycle was investigated. This cell line was found to be highly unstable. A simple batch‐growth model simulation was used as follows: (i) to demonstrate that nonproducers appear in hybridoma cell lines after a rare, random mutation event that results in the loss of the heavy‐chain gene and/or light‐chain gene expression; (ii) to show that a high rate of conversion of producer hybridomas to nonproducer hybridomas cannot entirely explain the population dynamics; (iii) to estimate the rate of conversion of producers to nonproducers to be 8.7 ± 10−5 h−1; (iv) to show that, for this conversion rate, the nonproducer cells' specific growth rates need only be 9% higher than those of the producer cells to dominate the hybridoma culture after only 25 passages; and (v) to predict that producer cells are preferentially lost during cell freezing and thawing procedures. The data suggest that particularly unstable cell lines should be analyzed and purified frequently to prevent overgrowth by nonproducers.
Rapid Quantitation of Recombinant Retroviruses
Authors: Morgan Jeffrey R. , Lee Jongwon , Tompkins Ronald G. , Yarmush Martin L. 
Published: March 2005

AbstractA method for measuring the concentration of recombinant retrovirus encoding the Escherichia coli LacZ gene is described. The assay is based on the quantitative measurement of β‐galactosidase activity in extracts of cells infected with the LacZ‐encoding retrovirus. LacZ‐encoded β‐galactosidase activity in transduced cells is measured using the colorimetric substrate, O;‐nitrophenyl β‐D‐galactopyranoside (ONPG), and the results are read using an ELISA plate‐reader. Because the entire assay is performed in a 96‐well plate, large numbers of samples are easily measured, and the assay has the advantages of rapidity, precision, and ease of data collection. The assay was used to determine the optimal concentration of polybrene, a polycation known to enhance the infectivity of retroviruses, and can be used to evaluate other factors that affect infection, as well as the optimal conditions for production of the recombinant retrovirus.
New Materials for Biotechnology: Chromatographic Stationary Phases Based on Zirconia
Authors: Nawrocki Jacek , Dunlap Christopher J. , Carr Peter W. , Blackwell John A. 
Published: March 2005

AbstractThis review explores the usefulness of zirconia‐based materials in separations in biotechnology. The physical and chemical properties of zirconia are discussed briefly to familiarize the reader with the advantages of zirconia. The use of native zirconia is then examined, with a study of the Lewis acid/base chemistry that defines chromatography with zirconia. Modification of the zirconia surface with small molecules is then discussed. Finally, polymer‐coated zirconia materials are examined. Examples of separations using these various materials are shown. The advantages and disadvantages of each of these materials are presented.
Suboptimal Control of Batch Fermentation Processes Based on Their Classification by the Peculiarity Index
Authors: Kazakov Alexandr V. , Ganipol'skiy Sergey L. 
Published: March 2005

AbstractA new method of suboptimal control for batch and fed‐batch fermentation processes is proposed. It combines the properties of program and adaptive control methods. The main idea of the method is to divide the controlled fermentation processes into classes using the integral characteristic of their individual properties‐the peculiarity index (PI). It is assumed that any process that belongs to a class is identical to the class' standard process (CSP). The optimal control programs for the CSP are derived off‐line. The value of PI for the current process is determined on‐line, and the control program that is used is the optimal one for the corresponding CSP. Industrial scale lysine fermentation processes are taken as an example. It is shown that the efficiency of the method is close to the efficiency of adaptive control, but that it is much simpler and its performance characteristics are better.
Stimulatory Effect of a Sulfonylurea Analogue and Its Polymer Conjugate on Insulin Secretion from Rat Islets
Authors: Kikuchi Akihiko , Bae You Han , Kim Sung Wan 
Published: March 2005

AbstractA sulfonylurea with a polymerizable end group (a glyburide analogue) was synthesized. This monomer was copolymerized with N, N‐dimethylacrylamide (DMAAm). In vitro bioactivity was evaluated by adding these sulfonylurea monomers and copolymers into normal rat islet cultures and measuring the insulin concentration in the supernatant. The sulfonylurea monomer showed a stimulatory effect on rat islets at glucose concentrations of 50 and 100 mg/dL, with equivalent stimulation indices for glyburide, the potent sulfonylurea drug, while no effect was observed at a glucose concentration of 200 mg/dL. The sulfonylurea polymer stimulated Langerhans islets to secrete insulin at a low glucose concentration of 50 mg/dL, with 80% bioactivity of its monomeric compound. However, at 100 and 200 mg/dL glucose concentrations, there was no significant stimulation in insulin secretion. Because it is suggested that the sulfonylurea receptors are located in the lipid phase on the ATP‐sensitive K+ channels, the solubilization of sulfonylurea into, and its diffusion through, the lipid phase in the cell membrane may affect the interactions of sulfonylurea with its receptors. In the case of the sulfonylurea polymer, the sulfonylurea unit in the polymer can interact with its receptor as can be seen by the increased insulin secretion at a glucose concentration of 50 mg/dL, but its interaction would be interfered with to some extent by a large hydrophilic polymer backbone. Thus, less change in insulin secretion was observed at higher glucose concentrations by the addition of this particular sulfonylurea polymer.
Isolation of Human Blood Cells, Platelets, and Plasma Proteins by Centrifugal SPLITT Fractionation
Authors: Fuh C. Bor , Giddings J. Calvin 
Published: March 2005

AbstractCentrifugal SPLITT fractionation, a technique designed for the continuous high‐resolution separation of colloids and low‐density particles, is applied here to fresh human blood, producing six purified fractions consisting of proteins and lipoproteins, platelets, red blood cells, lymphocytes, monocytes, and neutrophils. Production of the six fractions requires five steps, each yielding two fractions. These five steps are carried out in sequence using a single apparatus, with conditions varying from step to step in accordance with theoretical guidelines in order to achieve the desired cut points. In the first step, a stream of diluted blood is separated into one fraction consisting of platelets and plasma and another containing blood cells. The throughput of diluted blood is 162 mL/h and that of whole blood is about 2 mL/h or ∼1010 cells/h; guidelines are given for significantly increasing throughput. The purity of the blood cell fractions ranged from 92 to 98%, and the viability fell in the range 97–99%.
Flow Injection Analysis of Glucose, Fructose, and Sucrose Using a Biosensor Constructed with Permeabilized Zymomonas mobilis and Invertase
Authors: Park Je‐Kyun , Shin Min‐Chol , Lee Seung‐Goo , Kim Hak‐Sung 
Published: March 2005

AbstractCells of Zymomonas mobilis possessing glucose‐fructose oxidoreductase and glucono‐lactonase were permeabilized with toluene and co‐immobilized with invertase within a gelatin membrane. This membrane was coated over a pH electrode, and the resulting biosensor was placed in a flow‐through cell to develop a flow injection analysis (FIA) system for the specific determination of glucose, fructose, and sucrose. Peak height resulting from the production of hydrogen ion was correlated with sugar concentration, and the effect of operating variables on the response characteristics of the FIA system was investigated on the basis of theoretical and experimental analyses. Under the optimized conditions, the calibration curves for glucose, fructose, and sucrose were linear up to 8, 80, and 60 g/L, respectively. The FIA system was applied to the online monitoring of glucose production in the enzymatic hydrolysis of cellulose, and the glucose concentrations determined using the FIA system coincided well with those determined by the conventional enzymatic method.
Thermal Deactivation of Free and Immobilized β‐Glucosidase from Penicillium funiculosum
Authors: Aguado José , Romero M. Dolores , Rodríguez Lourdes , Calles José A. 
Published: March 2005

AbstractThermal deactivation of free and immobilized β‐glucosidase from Penicillium funiculosum has been studied in the temperature range 30–70 °C. Immobilization results in a remarkable increase in β‐glucosidase thermal stability. A two‐step series deactivation mechanism has been used to describe the experimental results for both free and immobilized β‐glucosidases. The kinetic equations resulting from this model fit our experimental results with a mean deviation of less than 10%.