bluuebunny/crossref_metadata_2025_split huggingface dataset:
Serial propagation of mammalian cells on microcarriers
Authors: Hu Wei‐Shou , Giard Donald J. , Wang Daniel I. C. 
Published: December 2004

AbstractFor the large‐scale operation of microcarrier culture to be successful, a technically feasible method for sequential inoculation is essential. Using human foreskin fibroblasts, FS‐4, we have achieved this by detaching cells viably from microcarriers employing a selection pH trypsinization technique. Cells thus detached are able to reattach to microcarriers and grow normally after subsequent reinoculation into new cultures. However, after reinoculation cells attach to new microcarriers at a higher rate than to used microcarriers on which cells have previously grown. The effect of this differential cell attachment was analyzed and overcome by employing a low inoculum concentration. FS‐4 cells could thus be serially propagated on microcarriers and subsequently used for β‐interferon production. This technique has also been applied to the cultivation of a monkey kidney cell line, Vero. We have also shown that Vero cells directly inoculated from a seed microcarrier culture could be used for virus production.
Bacterial adsorption to smooth surfaces: Rate, extent, and spatial pattern
Authors: Nelson C. H. , Robinson J. A. , Characklis W. G. 
Published: December 2004

AbstractThe influence of bulk‐water bacterial cell concentration and specific growth rate history on bacterial adsorption rates to surfaces was investigated using response surface analysis. A pure culture of Pseudomonas sp. 224S was grown in a chemostat and pumped into a continuous flow reactor where the bacteria were exposed to clean, glass surfaces under turbulent flow conditions for a period of six hours. Adsorption rate decreased approximately linearly with increasing specific growth rate history. Glass surfaces became saturated with 224S at ca. 0.1% coverage and the resulting spatial pattern of the adsorbed cells deviated from random in the direction of uniformity.
Use of the UASB reactor for the anaerobic treatment of stillage from sugar cane molasses
Authors: Sánchez Riera F. , Córdoba P. , Siñeriz F. 
Published: December 2004

AbstractThe feasibility of applying the UASB concept for the anaerobic treatment of stillage of distilleries in the sugar producing area of Argentina was subject to study. Results obtained in a 100‐L UASB reactor treating stillages with COD values between 35 and 100 g COD/L are presented. Loading rates of up to 24 g COD/L/day were applied with an average COD removal of 75% and a biogas production of more than 9 L/L/day, with an average methane content of 58%. The settling velocity distribution of sludge particles would indicate a good formation of biomass pellets. System interruptions of months without feed and at ambient temperature (20–24°C) were well tolerated.
Analysis of protein and cell volume distribution in glucose‐limited continuous cultures of budding yeast
Authors: Ranzi Bianca Maria , Compagno Concetta , Martegani Enzo 
Published: December 2004

AbstractMethod of flow cytometric analysis have recently been developed that make it possible to obtain segregated data on a single cell basis. In particular, it has been previously demonstrated that protein distributions obtained by flow cytometry give information about the law of growth of the cell population and the law of growth of the single cell; thus these distribution show how the microbial population is actually growing at the moment of the analysis and may yield more accurate and predictive information. We have extended the analysis of protein distribution and cell volume distribution to continuous cultures of Saccharomyces cerevisiae growing in a glucose‐limited chemostat. We have found that: (1) to each dilution rate corresponds a given protein and volume distribution that does not change with time in steady state cultures; (2) there is a good proportionality between the average cell volume and the average protein content; (3) the protein distribution obtained can be easily analyzed with the model of growth of yeast previously developed in our laboratory; (4) the analysis of perturbed states shows that both protein distribution and volume distribution change very quickly; thus they are very sensitive parameters and can be used for monitoring and controlling industrial fermentation.
Application of immobilized heparins for isolation of human antithrombin III
Authors: Mitra G. , Hall E. , Mitra I. 
Published: December 2004

AbstractImmobilized heparins were prepared by six different methods, and these were utilized for affinity purification of human antithrombin III (AT‐III). Affinity support capacities (mg AT‐III/g support) were strongly influenced by immobilized active heparin concentrations. In the temperature range 5–37°C, colder temperatures favored affinity adsorption of AT‐III as well as nonspecific interactions of all proteins. For representative human‐plasma‐derived feed solutions the selectivity for AT‐III on the affinity support was dependent on relative concentrations of non‐AT‐III proteins as well as the specific mode of adsorption and elution (batch/continuous).
Coupling of concanavalin A to cellulose hollow fibers for use in glucose affinity sensor
Authors: Srinivasan Keeran R. , Mansouri Sohrab , Schultz Jerome S. 
Published: December 2004

AbstractThis article describes a method for the chemical immobilization of concanavalin A (Con A) on the inside wall of a single hollow cellulose fiber for use in glucose affinity sensor. Periodate oxidation of cellulose fiber followed by a spacer for Con A attachment was deemed to be the most optimal procedure for achieving the highest sensitivity of the sensor without compromising its physical integrity. The effects of variables like the duration of periodate oxidation and its concentration and pH of the spacer coupling step and its duration have been examined. The mechanical strength of the hollow fiber as well as its permeability to the analyte (glucose) have been evaluated prior to and after Con A coupling process.It has been demonstrated that Con A bound hollow fiber prepared according to the procedure outlined here can be successfully used to construct glucose affinity sensor for operation in the physiological range of glucose concentrations.
Use of lipid solvents for viral inactivation in factor VIII concentrates
Authors: Mitra G. , Wong M. 
Published: December 2004

AbstractModel virus inactivation studies with lipid solvents were carried our in antihemophilic factor concentrates. The procoagulant activity obtained was ≥80% recovery with 20% amyl acetate–0.1% deoxycholate. A concurrent reduction of four logs of virus titer was obtained for model viruses provided the viral mass contained significant amounts (≥20%) of lipid. From this preliminary study it appears that further investigations in animal models may be warranted to demonstrate the inactivation of hepatitis B virus, non‐A–non‐B virus, and AIDS virus with 20% amyl acetate–0.1% deoxycholate in antihemophilic factor concentrates.
Rheometry of fermentation liquids
Authors: Kemblowski Z. , Kristiansen B. 
Published: December 2004

AbstractThis article is concerned with the measurements of rheological properties of nonhomogeneous fermentation liquids. In order to determine the flow curves of such liquids, an impeller measuring system of own design was used, and the method of calibration of the system is presented. The experimental verification was carried out using samples of fermentation broth of Aureobasidium pullulans and it has been shown that the applied measuring technique gives internally consistent results. The sensitivity of the technique proves its applicability for monitoring and control purposes in fermentation technology.
Growth kinetics of Dioscorea deltoidea and Catharanthus roseus in batch culture
Authors: Drapeau D. , Blanch H. W. , Wilke C. R. 
Published: December 2004

AbstractSugar‐limited batch growth of Dioscorea deltoidea and Catharanthus roseus plant cell cultures was studied in a 14‐L stirred tank fermentor. With dissolved oxygen concentration monitored and maintained at nonlimiting levels, growth rates and ratios of dry weight to fresh weight were found to be strongly influenced by sugar concentration. Linear relationships between respiration rate and growth rate were observed, and respiration rate was found to drop to a maintenance level after sugar had been fully depleted from the medium. Diosgenin biosynthesis by D. deltoidea was shown to be independent of growth rate. Ajmalicine biosynthesis in C. roseus was negligible during sugar‐limited growth but was induced by inoculation into an 80‐g/L glucose solution.
Biotreatment of s‐triazine‐containing wastewater in a fluidized bed reactor
Authors: Hogrefe W. , Grossenbacher H. , Cook A. M. , Hütter R. 
Published: December 2004

AbstractMixed cultures of microorganisms immobilized on sand were used to degrade s‐triazine‐containing industrial wastewater in a fluidized bed reactor. Immobilized cell concentrations of up to 18 g/L volatile suspended solids could be achieved with the s‐triazines as sole nitrogen source for growth and carbon sources added at a CN ratio of about 12. Maximal removal efficiencies of 80% of the s‐triazines could be maintained only if (a) the bio‐film thickness was limited to avoid oxygen deficiency and (b) the carbon source and complete wastewater (⩽50% v/v in the feed) were supplied continuously at a mean hydraulic residence time of ≥20–25 h.
Kinetics and mechanism of dissimilative Fe(III) reduction by Pseudomonas sp. 200
Authors: Arnold Robert G. , Olson Terese M. , Hoffmann Michael R. 
Published: December 2004

AbstractThe kinetics and mechanism of Fe(III) reduction to Fe(II) were studied in pure batch cultures of Pseudomonas sp. 200. The rate of iron reduction has been mechanistically related to aqueous phase iron speciation. In the absence of microbial activity the iron reduction rate was negligible. Initial rates of microbial iron reduction were accelerated more than 20‐fold by the addition of equimolar quantities of nitrilotriacetic acid (NTA) to media initially containing 1.86 × 10−3M total Fe(III). Numerical techniques were utilized to quantify relationships between the observed rate of Fe(II) production and the calculated (equilibrium) aqueous phase speciation. These results indicate that soluble ferric iron species are not equivalent in terms of their susceptibility to bacterial (dissimilative) iron reduction. The concentration of Fe(NTA)(OH) correlated strongly with observed iron reduction rates. Ferrous iron species appeared to inhibit the reduction process.
Phosphorylation of yeast protein: Reduction of ribonucleic acid and isolation of yeast protein concentrate
Authors: Huang Y.‐T. , Kinsella J. E. 
Published: December 2004

AbstractYeast nucleoproteins were chemically phosphorylated with phosphorus oxychloride (POCL3). Studies using 31P nuclear magnetic resonance (NMR) spectroscopy, stability to pH and lysine estimation all indicated that the ϵ‐amino group of lysine was the principal functional group phosphorylated. Phosphorylation of ca. 30% of the lysine residues resulted in removal of more than 85% of contaminant ribonucleic acid from protein precipitated at pH 4.2. Phosphorylation did not alter the amino acid composition of yeast proteins and was reversible under acidic conditions. Based on the data, a method for the preparation of phosphorylated yeast protein with low levels of nucleic acid is proposed.
Modeling active mass in aerobic sludge digestion
Authors: Droste R. L. , Sanchez W. A. 
Published: December 2004

AbstractAerobic digestion of waste‐activated sludge was carried out in lab‐scale reactors for both batch and semicontinuous flow patterns. The reactors were monitored at three different temperatures: 10, 20, and 30°C. During the course of digestion, significant solubilization of volatile suspended solids was observed, and its effect on the magnitude of kinetic coefficients was examined. Differences in metabolic activity and sludge stabilization were found between batch and semicontinuous flow patterns. An Arrhenius‐type relationship was not found to apply to rate constants for the semicontinuous reactors.
Anaerobic calorimetry of Zymomonas mobilis using a heat‐flux sensor
Authors: Silman Robert W. 
Published: December 2004

AbstractA relatively simple and inexpensive anaerobic calorimeter was designed and evaluated by using a Hy‐Cal Engineering BI‐7 bidirectional heat‐flux sensor to measure heat output from magnetically stirred I‐L flask fermentations. The production of ethanol and cumulative heat output by Zymomonas mobilis were both linearly proportional to glucose concentrations up to 160 g/L.
Mode of action and properties of xylanase and β‐Xylosidase from Neurospora crassa
Authors: Deshpande Vasanti , Lachke Anil , Mishra Chittra , Keskar Sulbha , Rao Mala 
Published: December 2004

AbstractExtracellular β‐xylosidase (1,4‐β‐D‐xylan xylohydrolase, EC 3.2.1.37) from culture filtrates of Neurospora crassa was purified to homogeneity by preparative isoelectric focusing followed by gel electrophoresis. The molecular weight of the purified xylosidase was 83,000 D and the Km on p‐nitrophenyl‐β‐D‐xyloside was 0.047mM. The homogeneous xylanase (1,4‐β‐D‐xylan xylanohydrolase, EC 3.2.1.8) and β‐xylosidase showed differences in their mode of action towards xylooligosaccharides. The degree of hydrolysis of D‐xylan by xylanase of N. crassa was 18%. Supplementation of β‐xylosidase from the same organism resulted in 48% hydrolysis. The synergistic effect was more pronounced, with the hydrolysis of 68%, when a homogeneous preparation of β‐xylosidase from Sclerotium rolfsii was added to the saccharification system.
The kinetics of growth of Proteus vuigaris in nicotinic acid‐limited cultures
Authors: Tseng Murray M‐C. , Phillips Colin R. 
Published: December 2004

AbstractProteus vulgaris is shown to take up nicotinic acid in the early stage of growth in amounts greater than needed for growth. The time variation of the specific nicotinic acid content of the cells, calculated by dividing the amount of nicotinic acid taken up from the liquid medium by the mass of cells present at that time, is interpreted to define two parameters, the maximum specific nicotinic acid content, f1, and the minimum content required for growth, f2 The difference, E, between these parameters is the specific nicotinic acid content capable of supporting growth for three doublings after depletion of nicotinic acid from the medium. A kinetic model for the system is developed based upon two stages of growth, a stage in which the cells accumulate from the medium their maximum nicotinic acid content, and a stage in the nicotinic acid‐depleted medium in which cell growth occurs at the expense of the cell‐bound nicotinic acid.
Kinetics of alcohol fermentations carried out in rotating biological surface reactors
Authors: Converti Attilio , Del Borghi Marco , Zilli Mario , Ferraiolo Giuseppe 
Published: December 2004

AbstractThis article aims at deriving kinetic models for the RBS reactor operating with and without cell porous support. Since derivation of the kinetic equations from the Monod model is very complex, an empirical derivation from experimental data of continuous alcohol fermentations is used in this work.
Improvement in separation characteristics of protein precipitates by acoustic conditioning
Authors: Hoare M. , Titchener N. J. , Foster P. R. 
Published: December 2004

AbstractThe effect of acoustic conditioning on the particle size distribution of isoelectric and calcium‐ion‐precipitated soya protein has been examined in low‐residence‐time chambers. In a previous study a beat frequency of 5 Hz obtained using a dual‐source system of opposing vibrators was determined as giving optimal improvement in particle‐settling characteristics for isoelectric soya protein precipitate. In this study the effect of amplitude of vibration, a measure of acoustic power input, and residence time of acoustic conditioning has been examined.Acoustic power input changed the flow pattern in the conditioning chamber from laminar streamline flow to a well‐mixed, turbulent pattern. Such a mixing effect promoted the rapid aggregation of fine particles, a process that was modeled on the basis of orthokinetically controlled collisions. The rate of removal of fine particles due to acoustic conditioning was shown to be proportional to a mixing effect that was releated to the acoustic power dissipated per unit volume.The consequences of fine‐particle aggregation on the centrifugal recovery of the precipitate are discussed.
Pretreatment of lignocellulosic materials with hydrogen peroxide in presence of manganese compounds
Authors: Takagi M. 
Published: December 2004

AbstractPretreatment of lignocellulosic materials such as newspaper, rice straw, pulp waste, and municipal solid waste with hydrogen peroxide in the presence of manganese compounds greatly enhances their susceptibility to enzymatic saccharification. This pretreatment can be achieved using rather mild conditions with only a minimal decrease in the recovery and little change in composition. Manganese salts in this hydrogen peroxide pretreatment works effectively in particular when the concentration of hydrogen peroxide is relatively low. The susceptibility of hydrogen‐peroxide‐pretreated substrate to enzymatic saccharification increases with increasing the molar ratio of manganes to hydrogen peroxide up to 1 : 100.
Effect of growth rate and expression level on plasmid stability in Saccharomyces cerevisiae
Authors: Parker C. , DiBiasio D. 
Published: December 2004

AbstractAn auxotrophic mutant of Saccharomyces cerevisiae, containing a recombinant 2‐μ‐based plasmid, was grown in selective media in continuous culture. The plasmid retained the ability to synthesize acid phosphatase as product, which was deleted from the host. Plasmid loss was followed at various dilution rates, and the level of plasmid expression was controlled by changing the β‐glycero/inorganic phosphate ratio.Some interesting trends were observed. As the level of plasmid expression was raised, the stability dropped markedly. Since acid phosphatase expression is regulated at the level of transcription, it is possible that increased transcription interfered with plasmid replication, hindered segregation, or overburdened the cell's DNA repair capability. It was also observed that plasmid stability was substantially increased at high growth rates. At dilution rates of 0.3 and 0.37 h−1, feeding only inorganic phosphate, the plasmid was completely stable.
Steroid conversions by Flavobacterium dehydrogenans in two‐liquid‐phase systems
Authors: Boeren Sjef , Laane Colja 
Published: December 2004

AbstractThe production of 4‐androstene‐3, 17‐dione by Flavobacterium dehydrogenans from androstenolone–acetate in octane/culture (v/v = 1:1) two‐liquid phase systems was compared with the conversion rate in a Tween‐containing medium commonly used in industry, and in a culture where no organic solvent or detergent was added. Variation of the cell density of the cultures at the moment of steroid, Tween, and/or organic solvent addition showed that the highest conversion rate in the three systems was reached with cells which were in the late exponential growth stage. The rate of 4‐androstene‐3, 17‐dione production at the optimal cell density in the two‐liquid‐phase system and Tween medium were ca. 6 and 1½ times as high, respectively, as in the aqueous medium without addition. The beneficial effect of octane on the rate of steroid conversion during growth could be explained by viability changes as measured by a new method to determine viability. Furthermore, our results show that a very high degree of conversion can be reached in the two‐liquid‐phase system [more than 98% (w/w)] which cannot be obtained in an aqueous medium. An easy way to recover the product in high purity is proposed.
Kinetics of milk coagulation: III. Mathematical modeling of the kinetics of curd formation following enzymatic hydrolysis of κ‐casein—parameter estimation
Authors: Carlson Alfred , Hill Charles G. , Olson Norman F. 
Published: December 2004

AbstractA step function model of milk micelle agglomeration is proposed to explain the observed kinetics of milk clotting following rennet addition. The model ties together the primary and secondary phases of coagulation. The basis of the model is that no micelle flocculation takes place until ca. 75% of the κ‐casein in the milk is hydrolyzed, at which time flocculation occurs rapidly and the rate limiting step for the clotting process shifts to the κ‐casein hydrolysis reaction. Using such a model, it is possible to explain the clotting kinetics for both rapidly denaturing enzymes and stable enzyme systems. The average rate of the flocculation reaction can be obtained from clotting time‐versus‐reciprocal‐enzyme‐concentration data by extrapolating the data to infinite enzyme concentration. The critical conversion required for imminent flocculation can be found by extrapolating the enzyme concentration to zero. This approach indicates that the critical conversion necessary for gelation is temperature dependent changing from a limiting value of essentially 100% hydrolysis at temperatures below 15°C to only 60% conversion at temperatures above 30°C.
Preparation of various glucose esters via lipase‐catalyzed hydrolysis of glucose pentaacetate
Authors: Shaw Jei‐Fu , Klibanov Alexander M. 
Published: December 2004

Abstractβ‐D(+)‐Glucose pentaacetate was hydrolyzed both chemically and enzymatically. In contrast to the alkaline hydrolysis, esterase‐catalyzed deacetylations afforded significant accumulation of intermediate glucose esters at different degrees of substrate conversion. Aspergillus niger lipase, the most suitable of the four enzymes tested, was used for preparative hydrolysis of glucose pentaacetate. As a result, gram quantities of pure glucose‐2,3,4,6‐tetraacetate, glucose triacetate (a mixture of two positional isomers, 2,4,6‐ and 3,4,6‐), and glucose‐4,6‐diacetate were prepared.
Aerobic oxidation of hydrogen sulfide by Thiobacillus denitrificans
Authors: Subletta Kerry L. 
Published: December 2004

AbstractIt has been demonstrated that Thiobacillus denitrificans may be readily cultured aerobically in batch and continuous flow reactors on H2S(g) under sulfide limiting conditions. Under these conditions sulfide concentrations in the culture medium were less than 1μM resulting in very low concentrations of H2S in the reactor outlet gas. Biomass yield under aerobic conditions was much lower than previously reported for anaerobic conditions, presumably because of oxygen inhibition of growth. However, biomass yield was not affected by steady state oxygen concentration in the range of 45μM–150μM. Biomass yield was also observed to be essentially independent of specific growth rate in the range of 0.030–0.053 h−1. Indicators of reactor upset were determined and recovery from upset conditions demonstrated. Maximum loading of the biomass for H2S oxidation under aerobic conditions was observed to be 15.1–20.9 mmol/h/g biomass which is much higher than previously reported for aerobic conditions. Other aspects of the stoichiometry of aerobic H2S oxidation are also reported.