bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling and experimental validation of carbon dioxide evolution in alkalophilic cultures
Authors: Noorman H. J. , Luijkx G. C. A. , Luyben K. Ch. A. M. , Heijnen J. J. 
Published: December 2004

AbstractThe chemical reactions involving carbon dioxide in mineral culture media are considered. A mathematic model is set up, based on published data, which is valid at pH values below 9, and in which the nonideality of the solution is taken into account. The crucial parameter is the constant expressing the equilibrium between carbon dioxide and bicarbonate, K1.The reactions were studied in three different aqueous solutions: water, mineral salt medium, and a suspension with nongrowing bacterial cells. For each situation, three methods were compared for the determination of the bicarbonate concentration in the solution: equilibrium state total carbon analysis, dynamic monitoring of the rate of acid or alkali addition, and dynamic measurement of the carbon dioxide gas phase mole fraction.In a batch‐stirred tank reactor, the equilibrium constant K1 agreed with the published value, and the three bicarbonate analysis methods give the same results. If the nonideality is not taken into account, the result significantly differed from the published value and is likely to be incorrect.A real alkalophilic process, using Acinetobacter calcoaceticus in a continuous stirred tank reactor at steady state, also gave results that are in accord with the literature. However, the results do not allow validation of the equation expressing the nonideality.The steady state in the batch system and in continuous culture can be well described with the mathematical model. However, in the transient state there are some unexplained differences between simulation and measurement.
Inner mitochondrial membranes bound to concanavalin A–sepharose display succinate dehydrogenase, ATPase, and cytochrome oxidase activity
Authors: Strasser Reto J. , Millán Lourdes , Darszon Alberto 
Published: December 2004

AbstractA fraction (15–20% of the total protein) of a preparation of bovine submitochondrial particles (SMPs) binds to concanavalin A–sepharose. The bound membranes displayed succinate dehydrogenase, cytochrome oxidase, and ATPase activity, which, as in SMPs, were inhibited by malonate, cyanide, and oligomycin, respectively. These results indicate that the bound membranes are inner mitochondrial membranes and that they contain a glycoprotein which was recognized by concanavalin A. It was possible to repeatedly perform the three enzyme assays, one after the other, in the same gel with the bound membranes. Long‐term stability tests (22 days) showed that cytochrome oxidase was much more stable in the membranes bound to the gel than in SMPs, while the ATPase activity decayed at a similar rate in the two conditions. Thus, inner mitochondrial membranes bound to ConA–Sepharose appear to be a potentially interesting model for the study of immobilized multienzymatic complexes.
Solubilization and regeneration of Vitreoscilla hemoglobin isolated from protein inclusion bodies
Authors: Hart Roger A. , Bailey James E. 
Published: December 2004

AbstractVitreoscilla hemoglobin (VHb), a homodimeric protein containing two heme groups in its native state, was used as a model to investigate inclusion body approtein solubilization, prosthetic group incorporation, and reactivation. High‐level expression in recombinant Escherichia coli results in accumulation of a substantial portion of heme‐free VHb in inclusion bodies. VHb can be solubilized from these inclusion bodies by relatively low concentrations of urea with the dissolution midpoint at approximately 3.2M urea. Dissolution in the presence of stoichiometric heme shifts the dissolution midpoint to approximately 4.5M urea without influencing the dissolution properties of contaminant proteins, suggesting the effect is specific for VHb. Denaturation of apoVHb and holoVHb obtained from purified native VHb has midpoints of 2.9M and 5.1M urea, respectively. VHb solubilized from inclusion bodies with urea at concentrations from 0 to 3.5M urea can be regenerated by heme addition without dilution of urea to yield active holoVHb. The fraction of solubilized VHb reconstituted upon heme addition is maximum at around 30% when solubilization and reconstitution is conducted in less than 1M urea. At these low urea concentrations, approximately 5% of inclusion body VHb is solubilized. These results show the utility of prosthetic group addition to reconstitute holoVHb in the presence of urea. Also, these findings suggest that some inclusion body protein has partially folded conformation and that a fractional dissolution and refolding process may be advantageous.
Changes of lipase‐catalyzed lipolytic rates in a batch reactor
Authors: Wang Y. J. , Wang F. F. , Sheu J. Y. , Tsai Y. C. , Shaw J. F. 
Published: December 2004

AbstractA dramatic change of the reaction rate was observed for the lipase‐catalyzed hyrolysis of tributyrin in a batch reactor. Immediately after the addition of the enzyme, the lipolysis rate increased continuously until a maximal reaction rate was reached. The duration of the induction was mainly controlled by the bulk enzyme concentration and the reactor stirring speed. The reaction rate dropped sharply after reaching its maximal value. The lipolysis decayed at a rate of about 0.012 min−1, and was not affected by changes of the stirring speed. This decay was attributed to the fast deactivation of the surface‐adsorbed lipase, and possibly to the extremely slow desorption of the inactivated species. For reaction time longer than 120 minutes, the lipolysis decreased at a much slower rate. Several mechanisms for the decay of the lipolysis rate were discussed.
A fluorescence‐based fiber optic biosensor for the flow‐injection analysis of penicillin
Authors: Xie Xiangfang , Suleiman Ahmad A. , Guilbault George G. 
Published: December 2004

AbstractA penicillin fiber optic sensor is described. The sensor is based on co‐immobilization of a pH indicator, fluorescein isothiocyanate (FITC), and penicillinase on a preactivated biodyne B membrane attached to the end of a bifurcated optical fiber. The characteristics of the sensor are investigated in conjunction with a flow injection analysis system. The proposed sensor is reversible and responds to penicillin in the concentration range of 1 × 10−4 to 5 × 10−2 mol/L. The application of this sensor to penicillin analysis in some pharmaceutical samples is demonstrated.
Fermentation of sweet whey by ethanologenic Escherichia coli
Authors: Guimaraes Walter V. , Dudey Gregory L. , Ingram L. O. 
Published: December 2004

AbstractWhey, an abundant byproduct of the dairy industry, contains large amounts of protein and lactose which could be used for fuel ethanol production. We have investigated a new organism as a candidate for such fermentations: recombinant Escherichia coli containing the genes encoding the ethanol pathway from Zymomonas mobilis. The highest level of ethanol achieved, 68 g/L, was produced after 108 hours in Luria broth containing 140 g lactose/L. Fermentations of lower lactose concentrations were completed more rapidly with approximately 88% of theoretical yields. Reconstituted sweet whey (60 g lactose/L)was fermented more slowly than lactose in Luria broth requiring 144 hours to produce 26 g ethanol/L. Supplementing sweet whey with a trace metal mix and ammonium sulfate reduced the required fermentation time to 72 hours and increased final ethanol concentration (28 g ethanol/L). By adding proteinases during fermentation, the requirement for ammonia was completely eliminated, and the rate of fermentation further improved (30 g ethanol/L after 48 hours). This latter incresed in rate of ethanol production and ethanol yield are presumed to result from incorporation of amino acids released by hydrolysis of whey proteins. The fermentation of sweet whey by ethanologenic E. coil reduced the nonvolatile residue by approximately 70%. This should reduce biological oxygen demand and reduce the cost of waste treatment. Whey supplemented with trace metals and small amounts of proteinase may represent an economically attractive feedstock for the production of ethanol and other useful chemicals.
A comparison of neural networks and partial least squares for deconvoluting fluorescence spectra
Authors: McAvoy Thomas J. , Su Hong Te , Wang Nam S. , He Ming , Horvath John , Semerjian Hratch 
Published: December 2004

AbstractThis article compares backpropagation neural networks (BNN) with partial least squares (PLS) techniques in terms of their ability to deconvolute fluorescence spectra. Both actual experimental and simulated spectral data are studied for 2 binary systems. These systems consist of mixtures of tryptophan and tyrosine, and NADH and tryptophan over a total concentration range of 10−7 to 10−4 M. It is shown that BNN is superior to PLS for both systems.
Mechanisms of protein solubilization in reverse micelles
Authors: Matzke S. F. , Creagh A. L. , Haynes C. A. , Prausnitz J. M. , Blanch H. W. 
Published: December 2004

AbstractSolubilization properties of α‐chymotrypsin and alcohol dehydrogenase (LADH) in reverse micelles are reported for three different solubilization techniques. The solubilization properties for these two proteins depend on the method used for protein addition. The addition of a dry protein powder to a reverse‐micelle‐containing organic phase does not appreciably solubilize the protein until the diameter of the reverse micelle is similar to that of the protein. However, when an aqueous protein solution is injected an organic phase, protein solubilization is not strongly dependent on micelle size. For chymotrypsin, multiple protein occupancy occurs at large micelle size, with as many as 11 chymotrypsin molecules solubilized in one reverse micelle. The solubilization of chymotrypsin using a phase‐transter technique with a positively charged surfactant follows the expected traned based on protein‐surfactant electrostatic interactions. When a negatively charged sufactants is used for phase transfer, at low pH the solubilization data do not fit this electrostatic interaction mechanism. In this case, proteinsurfactant aggregation may be occurring at the aqueousorganic interface.
Use of microbial electrodes for observation of microbiological nitrogen elimination process
Authors: Hikuma Motohiko , Matsuoka Hiroshi , Kawarai Masahiro , Karube Isao 
Published: December 2004

AbstractMicrobial electrodes for the determination of ammonia and the estimation of biochemical oxygen demand (BOD) were applied to the nitrogen elimination process. The dimensions of the nitrification and the denitrification vessels were 170 and 70 L, respectively. The wastewater used for the experiment was obtained from a fermentation factory and adjusted to 470–530 mg/L of total Kjeldahl nitrogen and 1700–3000 mg/L of BOD. The ammonia electrode was assembled with a membrane containing nitrifying bacteria and an oxygen probe. The BOD electrode was similarly constructed, except it used a membrane containing the yeast, Trichosporon cutaneum. A flow system was employed for the automatic measurement of samples every 30 min. The nitrification and denitrification rates of the activated sludge were measured to investigate the optimum conditions and evaluate the capacity of the plant. The various data obtained by the microbial electrodes allowed us to inspect the situation of the plant and estimate control paramerers such as nitrogen and BOD loadings. The average removals of ammonia nitrogen and total Kjeldahl nitrogen were 96% and 89%, respectively, during the experiment for period of 2 weeks.
Photosynthetic activity of cyanobacteria in water‐in‐oil microemulsions
Authors: Famiglietti M. , Hochköppler A. , Wehrli E. , Luisi P. L. 
Published: December 2004

AbstractThe solubilization and the photosynthetic activity of cyanobacteria (Anabaena variabilis) in water‐in‐oil microemulsions consisting of (Tween85/Span80)/hexadecane/water is investigated. Transparent and stable solutions containing up to 108 cells/mL could be obtained. The physical state and stability of the cells in the microemulsion, as evidenced from optical and electron microscopy, is dependent upon the physical parameters of the system, and in particular on the hydrophylic‐lypophilic balance (HLB) of the surfactant system. Conditions could be found, under which the cells in the microemulsion system display photosynthetic activity This was judged by measuring polarographically the oxygen evolution and by studying the photosynthetic activity in the presence of specific inhinbitors.
Functional immobilization of lipase eliminating lipolysis product inhibition
Authors: Kosugi Yoshitsugu , Suzuki Hideo 
Published: December 2004

AbstractLipase from Pseudomonas fluorescens biotype I was immobilized on macroporous anion exchange resin using glutaraldehyde to enhance the adsorption. The immobilization method was selected, because it provided the highest extent of hydrolysis of beef tallow at high substrate concentrations. The immobilized lipase was not substantially inhibited by oleic acid or sodium oleate, but the soluble lipase was strongly inhibited by both substances. The optimum pH of lipolysis was pH 4 for the immobilized lipase and pH 6 for the soluble one. These results indicate that the microenvironment created around the lipase molecule by immobilization eliminates product inhibition. In addition, the immobilization on the support enhances the stability of the lipase against chemical denuaturation. © 1992 John Wiley & Sons, Inc.
Effect of oxygen on steady‐state product distribution in Bacillus polymyxa fermentations
Authors: Mankad T. , Nauman E. B. 
Published: December 2004

AbstractBacillus polymyxa ferments glucose to 1‐2,3 butanediol, acetoin, ethanol, acetic acid, lactic acid, and formic acid. This research investigates product formation as a function of oxygen availability. A predictive model that simulates product distribution at known oxygen transfer rates is developed on the hypothesis that, in an energy‐limited environment, B. polymyxa utilizes glucose and oxygen in the most efficient manner. The efficiency of utilization of glucose and oxygen is measured in terms of the ATP yields of each oxidative pathway. The identity of the products constituting the profile at the given oxygen transfer rate is determined by comparing the ATP production and consumption rates. While the ATP generated is calculated from a knowledge of the oxygen transfer rate and ATP yields of the oxidative pathways, the ATP consumption is estimated by the Pirt expression in terms of growth‐ and nongrowth‐associated components. The product formation rates are obtained by solving ATP and NAD balance equations. They equate the production and consumption rates of these intermediates and are derived from the pseudo‐steady‐state hypothesis. The model is applied to continuous culture systems that are both open and closed with respect to biomass. At a given oxygen transfer rate, dilution rate, and inlet glucose concentration, the model predicts steady‐state concentrations of two dominant fermentation endproducts with the help of four parameters that can be determined from independent experiments. In contrast with earlier approaches, the experimental studies are carried out in continuous culture. Product profiles are obtained at various oxygen transfer rates, fer rates, inlet glucose concentrations, and dilution rates. The effect of pH on the relative distribution of products is also demonstrated. Results indicate that the model is fairly successful in predicting product profiles as a function of oxygen availability. © 1992 John Wiley & Sons, Inc.
Growth kinetics of the photosynthetic bacterium Chlorobium thiosulfatophilum in a fed‐batch reactor
Authors: Kim Byung Woo , Chang Ho Nam , Kim In Kyu , Lee Kang Suk 
Published: December 2004

AbstractHydrogen sulfide dissolved in water can be converted to elementary sulfur or sulfate by the photosynthetic bacterium Chlorobium thiosulfatophilum. Substrate inhibition occurred at sulfide concentrations above 5.7 mM. Light inhibition was found at average light intensities of 40,000 lux in a sulfide concentration of 5 mM, where no substrate inhibition occurred. Light intensity, the most important growth parameter, was attenuated through both scattering by sulfur particles and absorption by the cells. Average cell and sulfur particle sizes were 1.1 and 9.4 μm, respectively. Cells contributed 10 times as much to the turbidity as sulfur particles of the same weight concentration. The light attenuation factor was mathematically modeled, considering both the absorption and scattering effects based on the Beer‐Lambert law and the Rayleigh theory, which were introduced to the cell growth model. Optimal operational conditions relating feed rate vs. light intensity were obtained to suppress the accumulation of sulfate and sulfide and save light energy for 2‐ and 4‐L fed‐batch reactors. Light intensity should be greater for the same performance (H2S removal rate/unit cell concentration) in larger reactors due to the scaleup effect on light transmission. Knowledge of appropriate growth kinetics in photosynthetic fed‐batch reactors was essential to increase feed rate and light intensity and therefore cell growth. A mathematical model was developed that describes the cell growth by considering the light attenuation factor due to scattering and absorption and the crowding effect of the cells. This model was in good agreement with the experimental results. © 1992 John Wiley & Sons, Inc.
Effect of hydrogen sulfide on growth of sulfate reducing bacteria
Authors: Reis M. A. M. , Almeida J. S. , Lemos P. C. , Carrondo M. J. T. 
Published: December 2004

AbstractA culture of sulfate reducing bacteria (SRB) growing on lactate and sulfate was incubated at different pH values in the range of 5.8–7.0. The effect of pH on growth rate was determined in this pH range; the highest growth rate was observed at pH 6.7. Hydrogen sulfide produced from sulfate reduction was found to have a direct and reversible toxicity effect on the SRB. A hydrogen sulfide Concentration of 547 mg/L (16.1 mM) completely inhibited the culture growth. Comparison between acetic acid and hydrogen sulfide inhibition is presented and the concomitant inhibition kinetics are mathematically described. © 1992 John Wiley & Sons, Inc.
Iridium oxide pH microelectrode
Authors: VanHoudt Paulus , Lewandowski Zbigniew , Little Brenda 
Published: December 2004

AbstractThe manufacture, calibration, and signal conditioning during construction of an iridium/iridium oxide pH microsensor is described. The microsensor was designed to be used extracellularly, primarily in biofilm research. The sensing tip diameters were typically in the range of 3–15 μm. The iridium oxide was formed by potential cycling in dilute sulfuric acid. A pH profule across a denitrifying biofilm was measured as an example of an application. The higher Nernstian slope (70–80 mV/pH for fresh electrodes), increased rigidity, and restriction of the sensing tip to the outermost end of the electrode are features which make the iridium/iridium oxide pH microelectrode superior to a glass microelectrode. © 1992 John Wiley & Sons, Inc.
Investigation of production of dextran and dextransucrase by Leuconostoc mesenteroides immobilized within porous stainless steel
Authors: El‐Sayed Abdel‐Halim M. M. , Abdul‐Wahid Kamsani , Coughlin Robert W. 
Published: December 2004

AbstractCells of Leuconostoc mesenteroides were immobilized within porus, stainless‐steel (SS) supports and used for dextransucrase (DS) and dextran production. The pore size of the support significantly affected the dextran yields, which were greatest with average pore sizes of 2‐5 μm. All immobilized‐cell biocatalysts in porous stainless steel produced higher yields than free cells, with the exception of cells confined in submicrometer pores (0.5 μm). Coating supports of larger pore size (40 and 100 μm) with calcium alginate enhanced the cell‐loading capacity of the supports and increased dextran and fructose yields in the cell‐free broth. Controlled, fed‐batch, DS production (activation), as a step preliminary to dextran production, significantly improved the subsequent dextran and fructose yields and shortened the time required to attain the maximum such yields. Scanning electron microscopy (SEM) of immobilized L. mesenteroides in stainless steel shows an irregular pattern of the microorganism inside the pores of the solid supports. Coating the porous solid supports with a cell‐free calcium alginate layer led to an increase in the cell density inside the support. Cell growth inside the coated, porous stainless steel had no distinct growth form. © 1992 John Wiley & Sons, Inc.
Kinetics of methanogenic degradation of phenol by activated‐carbon‐supported and granular biomass
Authors: Craik S. A. , Fedorak P. M. , Hrudey S. E. , Gray M. R. 
Published: December 2004

AbstractA continuous‐feed recycle bioreactor was used to study the kinetics of methanogenic degradation of phenol at 35°C by bacteria supported on a bed of granular activated carbon (GAC). At dilution rates well above the growth rate of the culture, the cells not only populated the GAC, but also formed a layer of granular biomass. This layer was stabilized by the presence of the GAC, and accounted for over half of the phenol‐degrading activity in the bioreactor. The specific phenol degradation rates for GAC‐attached biomass, suspended biomass, and granular biomass were all in the range 0.15 to 0.22 mg phenol/mg volatile solids per day as measured under pseudo‐steady‐state conditions. © 1992 John Wiley & Sons, Inc.
Mammalian cell retention in a spinfilter perfusion bioreactor
Authors: Yabannavar V. M. , Singh V. , Connelly N. V. 
Published: December 2004

AbstractA spinning cylindrical filter is often used to retain mammalian cells in a continuous perfusion bioreactor. This device, known as a spinfilter, has typically been with pore size smaller than the cell particles (single cells or aggregates) in order to achieve cell separation. For single cells in suspension, such an operation cannot be sustained over a long period of time because of clogging of the filter surface. Recently, screens with openings larger than the average cell size have been used to reduce the incidence of clogging. In this article, we have investigated how the screen size affects cell retention. We also showed why it is necessary to optimize the rotational speed of the spinfilter in order to achieve cell retention and reduce screen clogging. Effects of bulk mixing and perfusion rate on screen fouling cell retention, and cell washout were also investigated. © 1992 John Wiley & Sons, Inc.
Maximization of lipid production by Rhodotorula gracilis CFR‐1 using response surface methodology
Authors: Prapulla S. G. , Jacob Z. , Chand Nagin , Rajalakshmi D. , Karanth N. G. 
Published: December 2004

AbstractIn this study, an attempt has been made to maximize the lipid production using response surface methodology (RMS). Levels of nitrogen, carbon, and inoculum were chosen as factors. The results indicated that inoculum level was very important in lipid production, followed by carbon and nitrogen levels. At higher levels of inoculum, the strain was found to be more tolerant to higher concentrations of sugar, and significantly increased lipid production was noticed. Through the fitted models of second order, as per RSM, carbon at 10.24%, nitrogen at 0.37 g/L, and inoculum at the 20% level resulted in maximum biosynthesis of lipids. © 1992 John Wiley & Sons, Inc.