bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reduced Formation of Byproduct Component C in Acarbose Fermentation by Actinoplanessp. CKD485–16
Authors: Choi Byoung Taek , Shin Chul Soo 
Published: December 2003

AbstractAcarbose fermentation was conducted by cultivation of Actinoplanessp. CKD485–16. Approximately 2,300 mg/L of acarbose was produced at the end of cultivation along with 600 mg/L of the acarbose byproduct component C. Maltose, a known moiety of acarbose, should be maintained at high concentration levels in culture broths for efficient acarbose production. The acarbose yield increased with an increasing osmolality of the culture medium, with a maximum value of 3,200 mg/L obtained at 500 mOsm/kg. Component C was also produced in proportion to the osmolality. Conversion of acarbose to component C was accomplished with resting whole cells. Inhibitors of the conversion of acarbose to component C were sought since component C is probably derived from acarbose. Valienamine was found to be a potent inhibitor, resulting in a more than 90% reduction in component C formation at a 10 μM concentration. Effects were similar in a 1,500‐L pilot fermentor with acarbose and component C yields of 3,490 and 43 mg/L at 500 mOsm/kg, respectively.
Oxidation‐Reduction Potential as a Control Variable for the Anaerobic Stage during Anaerobic‐Aerobic p‐Nitrophenol Degradation
Authors: Buitrón Germán , Betancur Manuel J. , Moreno Gloria , Moreno Jaime A. 
Published: December 2003

AbstractCombined anaerobic‐aerobic processes are a viable alternative for the treatment of xenobiotic compounds that are difficult to treat by traditional processes. The variable nature of the sequencing batch reactors, SBR, systems allows manipulation of the selective pressure on the microorganisms. Then, the activity of the community can be dynamically adjusted to meet changing effluents conditions. To improve the response of the SBR to changing influent conditions, several efforts have been made to automate and control the duration of the sequential phases of the SBR. The objective of this work is to present and discuss the feasibility of the use of the oxidation‐reduction potential, ORP, as a control variable for the determination of the anaerobic phase length in an anaerobic‐aerobic SBR used to degrade p‐nitrophenol, PNP. The control of the anaerobic phase of the anaerobic‐aerobic reactor was achieved with software developed at the Institute of Engineering‐UNAM. During the anaerobic stage, the PNP is reduced to p‐aminophenol, PAP. As a consequence of the compound transformation, there is a change in the oxidation‐reduction potential of the culture medium. This change was used to indicate the minimal concentration of PNP and, as a consequence, the maximal PAP concentration. The feasibility of the algorithm for using the variations in the ORP to determine on‐line the length of the anaerobic stage in an anaerobic‐aerobic process was demonstrated in our laboratory.
Using PC12 Cells To Evaluate Poly(caprolactone) and Collagenous Microcarriers for Applications in Nerve Guide Fabrication
Authors: Waddell Rebecca L. , Marra Kacey G. , Collins Kelly L. , Leung Jade T. , Doctor John S. 
Published: December 2003

AbstractTissue‐engineered nerve guides can provide mechanical support as well as chemical stimulation for nerve regeneration. PC12 cells were used to test the novel combination of poly(caprolactone) (PCL) and macroporous collagen‐based microcarriers (CultiSphers) as an initial phase in the fabrication of multichanneled nerve guides. Laminin‐coated PCL was an effective matrix for the attachment, proliferation, and viability of PC12 cells, relative to uncoated PCL. PC12 cells attached to laminin‐coated PCL and extended neurites when cultured in the presence of nerve growth factor (NGF). PC12 cells attached and proliferated on CultiSphers and extended neurites in response to NGF. A novel PCL/CultiSpher composite material also supported PC12 attachment and proliferation and provides a potentially useful material for the fabrication of synthetic nerve guides.
Assessment of In‐Line Near‐Infrared Spectroscopy for Continuous Monitoring of Fermentation Processes
Authors: Tosi Simona , Rossi Maddalena , Tamburini Elena , Vaccari Giuseppe , Amaretti Alberto , Matteuzzi Diego 
Published: December 2003

AbstractThe application of NIR in‐line to monitor and control fermentation processes was investigated. Determination of biomass, glucose, and lactic and acetic acids during fermentations of Staphylococcus xylosus ES13 was performed by an interactance fiber optic probe immersed into the culture broth and connected to a NIR instrument. Partial least squares regression (PLSR) calibration models of second derivative NIR spectra in the 700–1800 nm region gave satisfactory predictive models for all parameters of interest: biomass, glucose, and lactic and acetic acids. Batch, repeated batch, and continuous fermentations were monitored and automatically controlled by interfacing the NIR to the bioreactor control unit. The high frequency of data collection permitted an accurate study of the kinetics, supplying lots of data that describe the cultural broth composition and strengthen statistical analysis. Comparison of spectra collected throughout fermentation runs of S. xylosus ES13, Lactobacillus fermentum ES15, and Streptococcus thermophylus ES17 demonstrated the successful extension of a unique calibration model, developed for S. xylosus ES13, to other strains that were differently shaped but growing in the same medium and fermentation conditions. NIR in‐line was so versatile as to measure several biochemical parameters of different bacteria by means of slightly adapted models, avoiding a separate calibration for each strain.
Optimal NS0 Cell Growth in a Hollow Fiber Bioreactor Requires Increased Serum Concentration or a Cholesterol Supplement on the Cell Side of the Fiber
Authors: Gramer Michael J. , Maas Jodi 
Published: December 2003

AbstractAn NSO/GS cell line secreting a humanized antibody was routinely propagated in a T‐flask using 2% serum. For scale‐up of antibody production, this cell line was inoculated into a hollow fiber system using the same serum concentration. The metabolic activity increased for a few days in the hollow fiber system, but invariably the activity dropped dramatically as the cells died by day 7. A hollow fiber micro‐bioreactor was used as a screening tool to examine possible reasons for cell death in the large‐scale system. As seen in the hollow fiber system, cells died when 2% serum was used either on the cell side only or on both sides of the fiber in the micro‐bioreactor. In contrast, the use of 20% serum on the cell side of the fiber and basal medium on the non‐cell side resulted in good cell expansion at high viability. Regardless of the cell side serum concentration, no further growth enhancements were seen when up to 20% serum was placed on the non‐cell side of the fiber. These results suggest that a serum component that does not readily cross the fiber is limiting cell growth in the hollow fiber bioreactors. The addition of a cholesterol‐rich lipid supplement resulted in better cell growth in the micro‐bioreactor, while the addition of other non‐cholesterol lipid supplements resulted in no growth enhancement. The growth‐enhancing properties of the cholesterol supplement were more pronounced at lower serum concentrations, suggesting that poor growth at low serum concentration was due to suboptimal cholesterol levels. When the cell side serum concentration was increased to 20% in the hollow fiber system, cells grew and filled the bioreactor, allowing a 39‐day production run. These results demonstrate that this NSO cell line requires an increased cell side serum concentration for optimal growth and that this requirement is likely due to the inherent cholesterol dependency of this cell line.
Retroviral Delivery of the Ecdysone‐Regulatable Gene Expression System
Authors: Vaillancourt Peter , Felts Katherine A. 
Published: December 2003

AbstractWe describe a set of Moloney Murine Leukemia Virus (MoMLV)‐based replication‐defective retroviral vectors for delivery of the ecdysone‐inducible system into mammalian cells. The vector pFB‐ERV contains a tricistronic CMV expression cassette from which the ecdysone receptor proteins RXR and VgEcR are expressed, with the neo‐resistance marker expressed as the third open reading frame (ORF). The inducible vector pCFB‐EGSH contains an ecdysone‐inducible expression cassette inserted between the viral LTRs in the antisense orientation relative to that for the viral promoter. Potential interference from the proviral 5′ LTR is obviated due to a SIN deletion in the 3′ LTR. When used together, induction ratios of over 1000‐fold were achieved in NIH3T3 cells using firefly luciferase as a reporter.
Neural‐Network‐Based Identification of Tissue‐Type Plasminogen Activator Protein Production and Glycosylation in CHO Cell Culture under Shear Environment
Authors: Senger Ryan S. , Karim M. Nazmul 
Published: December 2003

AbstractAn artificial neural network (ANN) modeling scheme has been constructed for the identification of both recombinant tissue‐type plasminogen activator (r‐tPA) protein production and glycosylation from Chinese hamster ovary (CHO) cell culture, cultivated in a stirred bioreactor. A series of hybrid feed‐forward backpropagation neural networks were constructed to function as a software sensor. This enabled predictions of viable cell density, r‐tPA content, and r‐tPA glycosylation. The sensor was based on an initial input vector space consisting of simple metabolite concentrations, batch cultivation time, and a description of shear stress applied to the culture. Metabolite concentrations of the culture supernatant, included in the input vector space, were obtained from a single isocratic HPLC measurement. The shear stress component of the input space enabled accurate culture state prediction over a wide range of agitation rates. Coefficient of determination (r2) values between ANN predicted and experimental measurements of 0.945, 0.943, 0.956, and 0.990 were calculated to validate individual ANN prediction accuracy for total ammonia, apparent viable cell density, total r‐tPA, and Type II glycoform concentrations, respectively.
An Optimized Method for Aspergillusniger Spore Production on Natural Carrier Substrates
Authors: Bapat Prashant M. , Kundu Sucharita , Wangikar Pramod P. 
Published: December 2003

AbstractAspergillus niger spores have wide ranging applications in the fermentation industry as well as in wastewater treatment. We present an optimized method for production of A. niger spores on natural substrates such as rice, split pea, and millet. The specific productivity (number of spores per gram of dry substrate) was 31‐fold greater and volumetric productivity was 750‐fold greater compared to agar slopes. The important process variables were incubation temperature, moisture content, and inoculum quantity. We find that the optimal condition for total spore count is different from the viable spore count for millet. The optimum lies in a narrow region defined by the process parameters. Of the three substrates tested split pea gave the highest specific spore productivity of 3.1 × 1010 spores per gram of dry substrate. This is the first report of systematic study on the effect of process parameters on spore viability. The method of A. niger spore production on natural substrate appears advantageous as compared to the currently practiced method in terms of scale‐up, cost, and ease of operation.
Determination of Size Distribution and Encapsulation Efficiency of Liposome‐Encapsulated Hemoglobin Blood Substitutes Using Asymmetric Flow Field‐Flow Fractionation Coupled with Multi‐Angle Static Light Scattering
Authors: Arifin Dian R. , Palmer Andre F. 
Published: December 2003

AbstractIn this study, we investigated the size distribution, encapsulation efficiency, and oxygen affinity of liposome‐encapsulated tetrameric hemoglobin (LEHb) dispersions and correlated the data with the variation in extruder membrane pore size, ionic strength of the extrusion buffer, and hemoglobin (Hb) concentration. Asymmetric flow field‐flow fractionation (AFFF) in series with multi‐angle static light scattering (MASLS) was used to study the LEHb size distribution. We also introduced a novel method to measure the encapsulation efficiency using a differential interferometric refractive index (DIR) detector coupled to the AFFF‐MASLS system. This technique was nondestructive toward the sample and easy to implement. LEHbs were prepared by extrusion using a lipid combination of dimyristoyl‐phosphatidylcholine, cholesterol, and dimyristoyl‐phosphatidylglycerol in a 10:9:1 molar ratio. Five initial Hb concentrations (50, 100, 150, 200, and 300 mg Hb per mL of buffer) extruded through five different membrane pore diameters (400, 200, 100, 80, and 50 nm) were studied. Phosphate buffered saline (PBS) and phosphate buffer (PB) both at pH 7.3 were used as extrusion buffers. Despite the variation, extrusion through 400‐nm pore diameter membranes produced LEHbs smaller than the pore size, extrusion through 200‐nm membranes produced LEHbs with diameters close to the pore diameter, and extrusion through 100‐, 80‐, and 50‐nm membranes produced LEHbs larger than the pore sizes. We found that the choice of extrusion buffer had the greatest effect on the LEHb size distribution compared to either Hb concentration or extruder membrane pore size. Extrusion in PBS produced larger LEHbs and more monodisperse LEHb dispersions. However, LEHbs extruded in PB generally had higher Hb encapsulation efficiencies and lower methemoglobin (metHb) levels. The choice of extrusion buffer also affected how the encapsulation efficiency correlated with Hb concentration, extruder pore size, and the metHb level. The most optimum encapsulation efficiency and amount of Hb entrapped were achieved at the highest Hb concentration and the largest pore size for both extrusion buffers (62.38% and 187.14 mg Hb/mL of LEHb dispersion extruded in PBS, and 69.98% and 209.94 mg Hb/mL of LEHb dispersion extruded in PB). All LEHbs displayed good oxygen‐carrying properties as indicated by their P50 and cooperativity coefficients. LEHbs extruded in PB had an average P50 of 23.04 mmHg and an average Hill number of 2.29, and those extruded in PBS had average values of 27.25 mmHg and 2.49. These oxygen‐binding properties indicate that LEHbs possess strong potential as artificial blood substitutes. In addition, the metHb levels in PB‐LEHb dispersions are significantly low even in the absence of antioxidants such as N‐acetyl‐l‐cysteine.
Highly Efficient Conversion of Lactate to Pyruvate Using Whole Cells of Acinetobacter sp.
Authors: Ma Cui Qing , Xu Ping , Dou Yi Meng , Qu Yin Bo 
Published: December 2003

AbstractOn an industrial scale, the production of pyruvate at a high concentration from the cheaper lactate substrate is a valuable process. To produce pyruvate from lactate by whole cells, various lactate‐utilizing microorganisms were isolated from soil samples. Among them, strain WLIS, identified as Acinetobacter sp., was screened as a pyruvate producer. For the pyruvate preparation from lactate, the preparative conditions were optimized with whole cells of the strain. The cells cultivated in the medium containing 100 mM of l‐lactate showed the highest biotransformation efficiency from lactate to pyruvate. The optimized dry‐cell concentration, pH, and temperature of reaction were 6 g/L, pH 7.0–7.5, and 30 °C, respectively. The influences of ethylenediaminetetraacetic acid (EDTA) and aeration on a biotransformation reaction were carried out under the test conditions. Under the optimized reaction conditions, l‐lactate at concentrations of 200 and 500 mM were almost totally stoichiometrically converted into pyruvate in 8 and 12 h, respectively. About 60% of 800 mM of l‐lactate was transformed into pyruvate in 24 h. This reduced conversion rate is probably due to the high substrate inhibition in biotransformation.
Effects of Epidermal Growth Factor on Fibroblast Migration through Biomimetic Hydrogels
Authors: Gobin Andrea S. , West Jennifer L. 
Published: December 2003

AbstractWe have previously reported on the development and use of synthetic hydrogel extracellular matrix (ECM) analogues that can be used to study the mechanisms of migration. These biomimetic hydrogels consist of bioinert poly(ethylene glycol) diacrylate derivatives with proteolytically degradable peptide sequences included in the backbone of the polymer and adhesion peptide sequences grafted into the network. Cells adhere to the hydrogel via interaction between the grafted adhesion ligands and receptors on the cell surface. The cells migrate through the three‐dimensional system by secreting the appropriate proteolytic enzymes, which are involved in cell migration and are targeted to the peptide sequences incorporated in the backbone of the polymer. It was observed that cell migration has a biphasic dependence on adhesion ligand concentration, with optimal migration at intermediate ligand levels. In this study, we demonstrate that we can covalently attach epidermal growth factor (EGF) to PEG and graft them into the hydrogels. It was observed that EGF when tethered maintained mitogenic activity. It was also observed that fibroblast migration significantly increased in the presence of the grafted EGF through the collagenase‐sensitive hydrogels. In addition, the increase in migration was found to be independent from the proliferative response of the cells. These synthetic ECM analogues allow one to systematically control identities and concentrations of biomolecules and are useful tools to study mechanisms of cell migration.
Field‐Flow Fractionation as Analytical Technique for the Characterization of Dry Yeast: Correlation with Wine Fermentation Activity
Authors: Sanz Ramsés , Galceran M Teresa , Puignou Lluís 
Published: December 2003

AbstractImportant oenological properties of wine depend on the winemaking yeast used in the fermentation process. There is considerable controversy about the quality of yeast, and a simple and cheap analytical methodology for quality control of yeast is needed. Gravitational field flow fractionation (GFFF) was used to characterize several commercial active dry wine yeasts from Saccharomyces cerevisiae and Saccharomyces bayanus and to assess the quality of the raw material before use. Laboratory‐scale fermentations were performed using two different S. cerevisiae strains as inocula, and GFFF was used to follow the behavior of yeast cells during alcoholic fermentation. The viable/nonviable cell ratio was obtained by flow cytometry (FC) using propidium iodide as fluorescent dye. In each experiment, the amount of dry wine yeast to be used was calculated in order to provide the same quantity of viable cells. Kinetic studies of the fermentation process were performed controlling the density of the must, from 1.071 to 0.989 (20/20 density), and the total residual sugars, from 170 to 3 g/L. During the wine fermentation process, differences in the peak profiles obtained by GFFF between the two types of commercial yeasts that can be related with the unlike cell growth were observed. Moreover, the strains showed different fermentation kinetic profiles that could be correlated with the corresponding fractograms monitored by GFFF. These results allow optimism that sedimentation FFF techniques could be successfully used for quality assessment of the raw material and to predict yeast behavior during yeast‐based bioprocesses such as wine production.
Purification and Concentration of Alkaline Phosphatase by Selective Permeabilization of Escherichia coli Using Reverse Micellar Solutions
Authors: Bansal‐Mutalik Ritu , Gaikar Vilas G. 
Published: December 2003

AbstractRecovery of alkaline phosphatase (AP) from the periplasm of Escherichia coli using reverse micellar solutions (RMSs) of sodium dioctyl sulfosuccinate (AOT) in aliphatic hydrocarbons has been attempted. A variety of surface‐active agents, solvents, and reverse micellar conditions were screened, and an excellent recovery of the enzyme in a concentrated form, with a high purification factor, was obtained in a single‐step process. The permeabilization process strongly depended on the water content of the RMS as well as on the amount of water coating the microbial cell surface. The product was almost free from nucleic acids. In addition, because of the low affinity of AOT and the organic solvent for the aqueous phase, contamination by the permeabilizing agents would also be negligible.
Generation of a Telomere‐Based Episomal Vector
Authors: d'Aiuto Leonardo , Heras Jose I. de las , Ross Andrew , Shen Ming Hong , Cooke Howard 
Published: December 2003

AbstractWe have developed a telomere‐based episome by large‐scale amplification in Escherichia colicells. This episome consists of a PAC vector in which a 6 Kb sequence, containing an array of telomeric repeats spaced by a synthetic sequence, is tandemly repeated by large‐scale multimerization in E. coli. After transfection in human HT1080 cells, the construct, called clone 106, was able to persist in episomal form or integrated into some endogenous chromosomes. Integrations occurred exclusively at the telomeres. Episomes were still present in HT1080 cells after more than 100 days in the absence of selection. Integrations of clone 106 into the telomeric regions were retained only under selective conditions, and when the selection was removed the construct was progressively eliminated from the chromosome. The long‐term maintenance of clone 106 into human cells as an episome and its ability to integrate transiently into the telomeres of the host chromosomes suggest that this PAC‐based episome is potentially a good candidate vector for gene therapy applications.
Scale‐Up of a Liquid Static Culture Process for Hyperproduction of Ganoderic Acid by the Medicinal Mushroom Ganodermalucidum
Authors: Tang Ya‐Jie , Zhong Jian‐Jiang 
Published: December 2003

AbstractScale‐up of a liquid static culture process was studied for hyperproduction of ganoderic acid (GA) by a famous Chinese traditional medicinal mushroom, Ganoderma lucidum. Initial volumetric oxygen transfer coefficient (KLa) and area of liquid surface per liquid volume (As) were identified as key factors affecting cell growth and GA accumulation in liquid static cultures of G. lucidum, on the basis of which a multilayer static bioreactor was designed. At a low initial KLa level of 2.1 h‐1, a thick layer of white mycelia was formed on the liquid surface, and an optimal production of total GA (i.e., GA production in the liquid and on the liquid surface) was obtained. Both the formation of white mycelia and production of GA on the liquid surface were enhanced with an increase of As within the range as investigated (0.24–1.53 cm2/mL). At an As value of 0.90 cm2/mL, the total GA production reached maximum. A successful scale‐up from a 20‐mL static T‐flask to a 7.5‐L three‐layer static bioreactor was achieved based on initial KLa. The maximum biomass (20.8 ± 0.1 g DW/L), GA content (4.96 ± 0.13 mg/100 mg DW), and total GA production (976 ± 35 mg/L) were attained in static bioreactors. Not only GA content but also its production obtained in this work were the highest ever reported.