bluuebunny/crossref_metadata_2025_split huggingface dataset:
An investigation of the physico‐chemical basis of foaming in fungal fermentations
Authors: Noble Ian , Collins Mark , Porter Neil , Varley Julie 
Published: December 2004

AbstractA detailed physico‐chemical analysis of two foaming fungal fermentations was carried out to identify that key groups of compounds responsible for foam formation. Fermentations were carried out on a 20‐L scale in a stirred aerated tank, over 7 days, using a commercial, defined medium. The organisms investigated were Penicillium herqueii, a hyphomycete, and an unidentified Ingoldian fungus. Samples of broth and, where possible, foam were analyzed to determine which groups of compounds were concentrated into generated foams. Surface tension, bulk viscosity, and antifoam A concentration were additionally determined in broth samples. To date the cause of foaming in fermentations has been attributed to the surfactant properties of extracellular proteins. This assumption was tested and found to be incomplete as many additional groups of biochemicals were found to be enriched into the foam. The results of the investigation revealed the presence of proteins, carbohydrates, α‐keto acids, and lipophilic biosurfactants, particularly extracellular pigments, enriched within stable foams. © 1994 John Wiley & Sons, Inc.
Solids retention time in spherical biofilms in a biofilm airlift suspension reactor
Authors: Tijhuis L. , van Benthum W. A. J. , van Loosdrecht M. C. M. , Heijnen J. J. 
Published: December 2004

AbstractFluorescent microparticles were used as tracer beads to measure the dynamics of solids in spherical biofilms in a biofilm airlift suspension reactor. Attachment to, release from, and penetration into the biofilms of the tracer beads were measured. The coverage of the biofilm surface was low and the steady state particle concentration on the surface was dependent on the biofilm surface characteristics. The measured attachment rate constant was identical in both experiments and appeared to be determined by the hydrodynamic conditions in the turbulent reactor. The attachment rate was much faster than the release rate of the tracer beads and, therefore, the solidsretention time in the biofilm particle is not due to a simple reversible adsorption–desorption process. The heterogeneity of the distribution oftracer beads on different sectors on the biofilm surface decreased duringthe attachment period. Due to random detachment processes the heterogeneity of the tracer bead distribution increased during the release periodThe tracer beads quickly penetrated into the biofilm and became distributed throughout the active layer of the biofilm. The observed penetration into biofilms, the nonuniform distribution on the biofilm surface, and the fast uptake and slow release of tracer beads cannot be described by a simple model based on a reversible adsorption–desorption mechanism, nor withexisting biofilm models. These biofilm models, which balance growth and advection assuming a uniform biofilm with a homogeneous surface, are inadequate for the description of the observed solids retention time in biofilms. Therefore, a new concept of biofilm dynamics is proposed, in which formation of cracks and fissures, which are rapidly filled with growing biomass, combined with nonuniform local detachment, explains the observed fast penetration into the biofilm of tracer beads, the long residence time, and the nonuniform distibution of fluorescent microparticles. © 1994 John Wiley & Sons, Inc.
Evaluation of the hok/sok killer locus for enhanced plasmid stability
Authors: Wu Kuowei , Wood Thomas K. 
Published: December 2004

AbstractThe effectiveness of the hok/sok plasmid stability locus and mechanism of cloned‐gene loss was evaluated in shake‐flask cultures. Addition of the hok/sok locus dramitically increasedapparent plasmid segregational stability to the hok/sok− control. In terms of the number of generations before 10%of the population became plasmid‐free, segregational stability was increased by 11‐ to 20‐fold in different media in the absence of induction of the cloned‐gene (hok/sok+ plasmid stable for over 200 generations in all media tested). With constant expression of β‐galactosidase in the absence of an tibiotic, the segregational stability of the plasmid containing hok/sok was incresed more than 17‐ to 30‐fold when β‐galactosidase was expressed at 7–15 wt % of total cell protein. Although the hok/sok system stabilized the plasmid well infour different media (Luria‐Bertani (LB), LB glucose, M9C Trp, and a representative fedbatch medium), the ability of hok/sok to maintain the plasmid with induction of the cloned gene decreased as the complexity of the media increased. This result is better interpreted in terms of the influence of cloned‐gene expression on plasmidmaintenance; plasmid segregational stability decreased linearly as specificβ‐galactosidase activity increased. © 1994 John Wiley & Sons, Inc.
Pilot scale recovery of recombinant annexin V from unclarified escherichia coli homogenate using expanded bed adsorption
Authors: Barnfield Frej Ann‐Kristin , Hjorth Rolf , Hammarström Åke 
Published: December 2004

AbstractExpanded bed adsorption is a new downstream processing technique forcapture of proteins directly from unclarified feedstocks. Expanded bed adsorption reduces the number of operations in purification processes by combining clarification, concentration, and capture into one operation. It is based on stable fluidization and uses adsorbent particles with well‐defined size and density distributions, together with columns designed to giveeven liquid flow distribution. The bed expands as the adsorbent particles are lifted by an upward liquid flow through the column. The behavior of the expanded bed is similar to a packed chromatography bed due to very little back‐mixing of the adsorbent particles. The major benefit of using anexpanded bed is that adsorption can be carried out with unclarified feedstocks; there is no need for centrifugation or filtration to remove cells and debris. When the feedstock is applied, the target protein is captured by the adsorbent while cells and debris pass through the column unhindered. Washing is performed with the bed in an expanded mode, followed by elution of bound protein in a sedimented mode with downward flowDescribed in this article is the use of expanded bed adsorption for pilot scale recovery of recombinant human placental annexin V from an Escherichia coli ho mogenate. The description includes the whole procedure, from small‐scale method optimization to pilot scale. The recovery of annexin V was approximately 95% at both lab scale and pilot scale. During the trials, it was discovered that the expanded bed was affected by the biomass content and viscosity of the homogenate. The upper limits for these parameters were therefore investigated further. For the E. coli used in the application described here, homogenates with biomass dry weightup to 5% and viscosities up to 10 mPa s (at a shear rate of 1 s−1) worked best. It was, however, feasible to use homogenates with dry weight up to 7–8% and viscosities up to 50 mPa s (1 s−1). © 1994 John Wiley & Sons, Inc.
Soluble microbial products (SMP) in anaerobic chemostats
Authors: Noguera Daniel R. , Araki Nobuo , Rittmann Bruce E. 
Published: December 2004

AbstractThe production of soluble microbial products (SMP) in anaerobic systems was evaluated using chemostat reactors. Results from steady‐state and tracer experiments with 14C‐glucose and 14C‐acetate showed that significant amounts of SMP were produced during the acidogenesis of glucose, but that SMP did not accumulate during methanogenesis from acetate. In addition, at a retention time of 40 days, SMP comprised almost all of the effluent COD from the glucose‐fed chemostat. For shorter retention times, as low as 10 days, the SMP concentration remained almost constant, but its significance in the effluent COD was reduced due to the accumulation of intermediate volatile fatty acids. The results from a 14C‐tracer experiment in the glucose‐fed chemostat were used to evaluate the importance of including SMP formation and degradation in kinetic modeling of the methanogenic chemostats. Three models were evaluated: a model without SMP production, a model with SMP production but no degradation, and a model with SMP production and degradation, The results of this kinetic analysis indicate that the model that includes SMP production and degradation was the only one able to adequately represent the fate of 14C in the tracer experiment. The kinetic parameters were successfully used to predict steady‐state concentrations of SMP and to characterize the formation and degradation characteristics of the SMP. © 1994 John Wiley & Sons, Inc.
Effect of temperature on nucleotide pools and monoclonal antibody production in a mouse hybridoma
Authors: Barnabé N. , Butler M. 
Published: December 2004

AbstractThe specific monoclonal antibody productivity (qMab) of a murine hybridoma (CC9C10) increased with incubation temperature in the range 33°C to 39°C. qMab was constant at each temperature and was independent of the phase of culture. The qMab increased 97% at 39°C and decreased by 21% at 33°C compared with controls at 37°C. Specific rates of substrate (glucose and glutamine) utilization and byproduct (lactate and ammonia) formation also increased with temperature but the yield coefficient, YLac/Llc' was constant for 33°C to 39°C and YAmm/Gin was constant for 37°C to 39°C. YAmm/Gin at 33°C was lower than the control. Changes in specific nucleotide concentrations and ratios were monitored by analysis of intracellular nucleotide pools. The NTP ratio, (ATP + GTP)/(UTP + CTP), increased and the U‐ratio (UTP/UDP–GNac) decreased during the course of each culture, whereas the adenylate energy charge, (ATP + 0.5ADP)/(ATP + ADP + AMP), remained relatively constant at a value 0.8. The relative content of UDP‐/N acetyl galactosamine, UDP‐N acetyl glucosamine, and NAD increased with incubation temperature, whereas the relative ATP content, SA(ATP + ADP + AMP)/SU (UTP + UDP‐sugars) ratio, purine/pyrimidine, ATP/GTP, and U‐ratio decreased at higher incubation temperatures. It is possible that these nucleotide parameters may have a regulatory role in the changes of qMab observed at the higher temperatures. © 1994 John Wiley & Sons, Inc.
Evaluation of D‐amino acid oxidase from Rhodotorula gracilis for the production of α‐keto acids: A reactor system
Authors: Butò Simona , Pollegioni Loredano , D'Angiuro Luigi , Pilone Mirella S. 
Published: December 2004

AbstractThe study reports on the development of a bioreactor for the production of α‐keto acids from D,L‐ or D‐amino acids using Rhodotorula gracilis D‐amino acid oxidase. D‐Amino acid oxidase was co‐immobilized with catalase on Affi‐Gel 10 matrix, and the reactor was operated as a continuous‐stirred tank reactor (CSTR) or stirred tank with medium recycling conditions. The optimum substrate concentration and quantity of biocatalyst were determined (5 mM and 1.2 mg/L, respectively). Under optimum operating conditions, product formation was linearly related to both substrate and enzyme concentration, showing the system to be highly flexible. Under these conditions, in a stirred tank, over 90% conversion was achieved in 30 min with a maximum production of 0.23 g of pyruvic acid/day/enzyme units. Product was recovered by ion exchange chromatography. The operational stability of the reactor was high (up to 9.5 h of operation without loss of activity) and the inactivation half‐life was not reached even after 18 h or 36 bioconversion cycles. This represents the first case of a reactor developed successfully with a D‐amino acid oxidase. © 1994 John Wiley & Sons, Inc.
Purification and processing of cellulose‐binding domain‐alkaline phosphatase fusion proteins
Authors: Greenwood Jeffrey M. , Gilkes Neil R. , Miller Robert C. , Kilburn Douglas G. , Warren R. Antony J. 
Published: December 2004

AbstractFusion of the leader peptide and the cellulose‐binding domain (CBD) of endoglucanase A (CenA) from Cellulomonas fimi, with of without linker sequences, to the N‐terminus of alkaline phosphatase (PhoA) from Escherichia coli leads to the accumulation of significant amounts of the CBD–PhoA fusion proteins in the supernatants of E. coli cultures. The fusion proteins can be purified from the supernatants by affinity chromatography on cellulose. The fusion protein can be desorbed from the cellulose with water or guanidine‐HCl. If the sequence IEGR in present between the CBD and PhoA, the CBD can be cleaved from the PhoA with factor Xa. The efficiency of hydrolysis by factor Xa is strongly in fluenced by the amino acids on either side of the IEGR sequence. The CBD released by factor Xa is removed by adsorption to cellulose. A nonspecific proteases from C. fimi, which hydrolyzes native CenA between the CBD and the catalytic domain, may be useful for removing the CBD from some fusion proteins. © 1994 John Wiley & Sons, Inc.
Effect of vitreoscilla hemoglobin expression on growth and specific tissue plasminogen activator productivity in recombinant chinese hamster ovary cells
Authors: Pendse Girish J. , Bailey James E. 
Published: December 2004

AbstractPrevious studies suggest that secretion of cloned proteins synthesized by recombinant Chinese hamster ovary (CHO) cells can be adenosine triphosphate (ATP) limited. Other research indicates that the presence of cloned Vitreoscilla hemoglobin (VHb) enhances ATP production in oxygen‐limited Escherichia coli. To evaluate the influence of VHb expression on recombinant CHO cell productivity, the vhb gene has been fused to the mouse mammary tumor virus (MMTV) promoter and cloned in a CHO cell line previously engineered to express human tissue plasminogen activator (tPA). Western blot analysis confirms dexamethasone‐inducible VHb expression in all of the clones tested. Batch cultivation experiments with one VHb‐expressing clone and the parental CHO‐tPA expressing cells. The VHb‐expressing clone exhibits specific tPA production 40 to 100% greater than the parental CHO‐tPA culture. © 1994 John Wiley & Sons, Inc.
On‐line gas analysis in animal cell cultivation: I. Control of dissolved oxygen and pH
Authors: Oeggerli A. , Eyer K. , Heinzle E. 
Published: December 2004

AbstractTo monitor gas reaction rates in animal cell culture at constant dissolved oxygen concentration (DO) and constant pH it was necessary to develop improved control methods. Decoupling of both controllrs was obtained by manipulation of molar fractions of oxygen and carbon dioxide in the gas phase. Two pairs of DO and pH controllers were designed and tested both in simulation and exprimental runs. The first controller pair was developed for headspace aeration only, whereas the second controller pair was designed for bubble aeration using a microsparger and flushing the headspace with helium. pH was controlled by a conventional discrete PID controller in its velocity form. For DO control two linear state space feedback controllers with parameter adaptation were established. In these controllers the oxygen uptake rate (OUR) was considered as a disturbance and was not included in the mathematical model. The feedback gain adaptation was based on the difference between the actual molar fraction of oxygen at time step n and the initial molar fraction. This difference is related to OUR and was used to increase or decrease the state feedback controller gain (k and k1, respectively) in a slow manner. With these controllers it was possible to get an excellent online estimate of OUR. In the case of bubble aeration a simple gas phase mass balance was sufficient, whereas during the headspace aeration a liquid phase balance was required. It has been shown that determination of OUR using gas balance requires a significantly better controller performance compared to just keeping DO and pH within reasonable limits. © 1995 John Wiley & Sons, Inc.
Starvation‐induced programmed death of hybridoma cells: Prevention by amino acid mixtures
Authors: Franěk F. 
Published: December 2004

AbstractAssociation of the availability of nutrients with the phenomenon of programmed cell death—apoptosis—was investigated using hybridoma cells cultured in protein‐free medium under conditions of starvation, i.e., in RPMl‐1640 medium diluted to 50% with saline. Amino acid mixtures, such as MEM essential amino acids or MEM nonessential amino acids were found to prevent starvation death significantly when added to the diluted medium in 1 to 2 mM concentrations, the MEM vitamin mixture was ineffective, and glutamine displayed a moderate growth‐supporting effect. The specific monoclonal antibody production rate in cultures supplemented with amino acid mixtures was strikingly low, whereas supplementation with glutamine alone or simultaneously with other amino acids resulted in a specific antibody production rate comparable with the rate observed in undiluted medium. © 1995 John Wiley & Sons, Inc.
The Monod equation and mass transfer
Authors: Merchuk J. C. , Asenjo J. A. 
Published: December 2004

AbstractAn alternative interpretation of the growth rate–substrate concentration dependence is presented. This is based on the assumption that the main factors affecting growth rate are transfer of substrate from the medium and the maximum growth velocity, which is that observed when no substrate limitations occur. This approach allows the approximate prediction of one of the two kinetic constants required, and may be of great use, especially for continuous cultures. It is the first attempt to provide a phenomenological explanation for the large variations observed in the values of the Monod constant, Ks, reported in the literature. © 1995 John Wiley & Sons, Inc.
Molecular assembly of proteins and conjugated polymers: Toward development of biosensors
Authors: Ayyagari Madhu S. , Pande Rajiv , Kamtekar Snjay , Marx Kenneth A. , Tripathy Sukant K. , Gao Harry , Kumar Jayant , Akkara Joseph A. , Kaplan David L. 
Published: December 2004

AbstractA molecular assembly in which a conjugated polymer is interfaced with a photodynamic protein is described. The conjugated polymer, functionalized with biotion, is designed such that it can be physisorbed on or chemically grown off a glass surface. The streptavidin‐derivatized protein is immobilized on the biotinylated polymer matrix through the strong biotin–streptavidin interactions. The assembly, built on the surface of an optical fiber or on the inside walls of a glass capillary, forms an integral part of a biosensor for the detection of environmental pollutants such as organophosphorus‐based insecticides. The Protein in the system can be replaced by any biological macromolecule of interest. We study one specific case, the enzyme alkaline phosphatase. The enzyme catalyzes a reaction producing an intermediate compound that chemiluminesces, and the chemiluminescence singnal is monitored to detect and quantify insecticides such as paraoxon and methyl parathion. Preliminary results indicate ppb level detection with response time less than 1 minute. © 1995 John Wiley & Sons, Inc.
A study of mass transfer in yeast in a pulsed baffled bioreactor
Authors: Ni Xiongwei , Gao Siwen , Pritchard Dave W. 
Published: December 2004

AbstractWe report experimental data of mass transfer of oxygen into yeast resuspension in a pulsed baffled bioreactor. The bioreactor consists of a 50‐mm‐diameter column with the presence of a series of either wall (orifice) or central (disc) baffles or a mixture of both where fluid oscillation can also be supermposed during the experiments. Air bubbles are sparged into the bottom of the pulsed baffled bioreactor, and the kinetics of liquid oxygen concentration in the yeast solution is followed using a dissolved oxygen probe with a fast response time of 3 s together with the dynamic gassing‐out technique. Among the three different baffle geometries investigated, the orifice baffles gave the highest and sharpest increase in the oxygen transfer rate, and the trends in the kLa measurements are consistent with the fluid mechanics observed within both the systems and previous work. In addition, we have also compared the kLa values with those obtained in a stirred tank; an 11% increase in the KLa is reported. © 1995 John Wiley & Sons, Inc.
A novel recycle batch immobilized cell bioreactor for propionate production from whey lactose
Authors: Yang Shang‐Tian , Huang Yan , Hong Gene 
Published: December 2004

AbstractRecycle batch fermentations using immobilized cells of Propionibacterium acidipropionici were studied for propionate production from whey permeate, de‐lactose whey permeate, and acid whey. Cells were immobilized in a spirally wound fibrous sheet packed in a 0.5‐L column reactor, which was connected to a 5‐L stirred tank batch fermentor with recirculation. The immobilized cells bioreactor served as a breeder for these recycle batch fermentations. High fermentation rates and conversions were obtained with these whey media without nutrient supplementation. It took ∼55 h to ferment whey permeate containing ∼45 g/L lactose to ∼20 g/L propionic acid. Higher propionate concentrations can be produced with various concentrated whey media containing more lactose. The highest propionic acid concentration obtained with the recycle batch reactor was 65 g/L, which is much higher than the normal maximum concentration of 35 to 45 g/L reported in the literature. The volumetric productivity ranged from 0.22 g/L · h to 0.47 g/L · h, depending on the propionate concentration and whey medium used. The corresponding specific cell productivity was 0.033 to 0.07 g/L · g cell. The productivity increased to 0.68 g/L · h when whey permeate was supplemented with 1% (w/v) yeast extract. Compared with conventional batch fermentation, the recycle batch fermentation with the immobilized cell bioreactor allows faster fermentation, produces a higher concentration of product, and can be run continually without significant downtime. The process also produced similar fermentation results with nonsterile whey media. © 1995 John Wiley & Sons, Inc.
Performances of a full‐scale novel multiplate anaerobic reactor treating cheese whey effluent
Authors: Guiot S. R. , Safi B. , Frigon J. C. , Mercier P. , Mulligan C. , Tremblay R. , Samson R. 
Published: December 2004

AbstractA 450‐m3 multiplate anaerobic reactor (MPAR) has been started‐up in April 1992 for treating wastewater (whey permeate and domestic wastewater) at the Nutrinor (Lactel) cheese factory in Chambord (Québec, Canada). The MPAR consists of four superimposed sections. The liquid flows upwards from one section to the next, while the gas is collected below each plate and evacuated through side‐outlets. The wastewater is concurrently distributed at the bottom of the first, second, and third sections, as 50%, 33%, and 17% of the total influent stream, respectively. Granular anaerobic sludge at an initial concentration of 30 kg of volatile suspended solids (VSS) per cubic meter of reactor liquid volume was used to inoculate the reactor. Under normal operation of the factory, the chemical oxygen demand (COD) concentration of the influent ranged from 20 to 37 kg COD m−3. The reactor organic loading rate (OLR) fluctuated between 9 and 14.7 kg COD m−3 d−1 for hydraulic retention times (HRT) maintained between 55 and 68 h. At the highest OLR, the MPAR showed an efficiency of 98% and 92% for soluble and total COD removal, respectively, and a methane production rate averaging around 4 m3 m−3 d−1.Biomass‐specific activities ranged between 7 and 51, 1.3 and 8.5, 5.3 and 12.2, 60 and 119, and 119 and 211 mmol g−1 VSS d−1 for glucose, propionate, acetate, formate, and hydrogen, respectively. Average equivalent‐diameter of the granules was around 0.65 mm. The MPAR reactor generally showed a large capacity for solid retention with a biomass content between 32 and 37 kg VSS m−3. © 1995 John Wiley & Sons, Inc.