bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance of the continuous glucose isomerase reactor system for the production of fructose syrup
Authors: Ryu D. Y. , Chung S. H. , Katoh K. 
Published: December 2004

AbstractGlucose isomerase in the form of heat‐treated whole‐cell enzyme prepared from Streptomyces phaeochromogenus follows the reversible single‐substrate reaction kinetics in isomerization of glucose to fructose. Based on the Kinetic constants determined and the mathematical model of the reactor system developed, the preformance of a plug‐flow‐type continuous‐enzyme reactor system was studied experimentally and also simulated with the aid of a computer for the ultimate objective of optimization of the glucose isomerase reactor system.The enzyme decay function for both the enzyme storage and during the use in the continuous reactor, was found to follow the first‐order decay kinetics. When the enzyme decay function is taken into consideration, the ideal homogeneous enzyme reactor kinetics provided a satisfactory working model without further complicatin of the mathematical model, and the results of computer simulation were found to be in good agreement with the experimental results. Under a given set of constraints the performance of the continuous glucose isomerase reactor system can be predicted by using the computer simulation method described in this paper.The important parameters studied for the optimization of reactor operation were enzyme loading, mean space time of the reactor, substrate feed concentration, enzyme decay constants, and the fractional conversion, in addition to the kinetic constants. All these parameters have significant effect on the productivity.Some unique properties of the glucose isomerization reaction and its effects on the performance of the continuous glucose isomerase reactor system have been studied and discussed. The reaction kinetics of glucose isomerase and the effects of both the enzyme loading and the changes in reaction rate within a continuous reactor on the productivity are all found to be of particular importance to this enzyme reactor system.
Degradation of polysaccharides by endo‐ and exoenzymes: Dextran–dextranase model systems
Authors: Wheatley M. A. , Moo‐Young M. 
Published: December 2004

AbstractExperiments were carried out on dextran–dextranase systems to test the prediction of a mechanistic model recently proposed by us, for the synergistic effect of combined exo/endo enzymic action in the degradation of polymeric substrate. Soluble forms of the substrate were used. Preliminary experiments with an insoluble form of the substrate were also carried out to demonstrate the applicability of the analytical techniques to these cases. Molecular weight distributions of the degradation products were determined (by gel‐permeation chromatography) and the rates of production of glucose and of other reducing sugars were also measured. It was found that the exodextranase alone had very little effect on the molecular weight distributions compared to a significant shift towards lower molecular weight obtained with the endodextranase which was synergistically enhanced by the action of the combined enzymes. Glucose was produced more rapidly by the exoenzyme compared to the endoenzyme, but combinations of the two enzymes gave a rate enhancement greater than the linear sum of the effects of the two individual enzymes. In comparing the degradation indices and polydispersities of the various degradation products, similar synergistic effects of the combined enzymes in accordance with the theoretical predictions, were observed. The practical implications of these findings to the design of fermentation processes which depend on the action of endo‐ and exoenzyme mixtures are noted.
Properties of enzymes immobilized by the diazotized m‐diaminobenzene method
Authors: Gray Charles J. , Livingstone Catherine M. 
Published: December 2004

AbstractSome properties of a number of enzymes immobilized by the diazotized m‐diaminobenzene (dDAB) method are described. The pH‐activity profiles of β‐D‐glucosidase, glucoamylase, peroxidase, uricase, and D‐glucose oxidase were virtually unchanged on immobilization while those of catalase and dextranase were significantly altered. β‐D‐Glucosidase, glucoamylase, and glucose oxidase were found to be more susceptible to denaturation on lyophilization when immobilized than in the native state; however, sorbitol had a marked protective effect in every case examined. Sorbitol was also found to exert a stabilizing effect when lyophilized immobilized preparations were stored. Immobilization marginally improved the stabilities of a number of enzymes to heating at 60° at pH 8.0. The usefulness for continuous reaction of a column of glucoamylase attached to celite was established. The reuse of the solid supports was demonstrated.
An analysis of extended and exponentially‐fed‐batch cultures
Authors: Lim Henry C. , Chen Bill J. , Creagan Christopher C. 
Published: December 2004

AbstractUnder certain conditions it is shown that an extended culture is equivalent to an exponentially‐fed‐batch culture, that an exponentially‐fed‐batch culture (and an extended culture) can be maintained at a steady state and that an exponentially‐fed‐batch culture may be mimicked by a continuous‐flow culture with a constant dilution rate. Operational conditions required to maintain steady states are specified.
Computation of the fraction of induced cells in enzyme induction systems
Authors: Von Stockar Urs , Yang Ren Der , Wilke Charles R. 
Published: December 2004

AbstractA theoretical model is developed for continuous multistage enzyme production systems, which consist of a growth fermentor used for growing microorganisms rapidly without enzyme production and a subsequent system of induction reactors in which enzymes induction and production occurs. The model allows the computation of the fraction of induced cells residing in the induction reactor for organisms exhibiting a lag phase in enzyme induction. For this model a general analytical solution was obtained for the cumulative internal residence time distribution of a series of n well‐stirred vessels with a recycle. The theoretical results are compared in a preliminary way with experimentally measured cellulase productivities of continuous multistage cellulose fermentations with Trichoderma viride QM 9414.
A reassessment of mixing cost in fermentation processes
Authors: Ryu Dewey Y. , Oldshue J. Y. 
Published: December 2004

AbstractThe gas–liquid oxygen transfer rate is a key step in the production of antibiotics in submerged fermentation. If the gas–liquid oxygen mass transfer rate is not equal to the required liquid–solid oxygen mass transfer rate at a particular cell concentration, then productivity of the particular fermentation operation will not be the maximum possible value.One way to increase the productivity of a given fermentation tank installation is to increase the cell concentration and to increase the oxygen transfer by changing the mixer and air supply to match the new requirements. In order to evaluate the cost of making this change to the larger mixing equipment, a typical cost example is given which can easily be modified for other combinations of production cost and mixer cost. As an example, it is seen that a considerable savings can result from a given installation by primarily changing the oxygen transfer ability of the equipment to utilize a given fermentor more efficiently. Production cost savings of 8 to 25% are shown in the example cited.
The enzymatic conversion of L‐histidine to urocanic acid by whole cells of Micrococcus luteus immobilized on carbodiimide activated carboxymethylcellulose
Authors: Jack T. R. , Zajic J. E. 
Published: December 2004

AbstractWhole cells of Micrococcus luteus (formerly Sarcina lutea ATCC 9341) have been covalently linked to a carboxymethylcellulose support system, with the retention of histidine ammonia–lyase activity. The dependence of the rate of urocanic acid formation on pH, temperature, and added surfactant concentration was similar for the free and the immobilized cells.The immobilization procedure used is based on the carbodiimide activation of carboxymethylcellulose and has been optimized for the histidine ammonia–lyase activity of the immobilized cells on a given weight of cellulose.In a column reactor at 23°C and superficial velocity of 0.044 cm/min, 5 g of cellulose with bound cells gave a 35% conversion of an L‐histidine solution (0.25M, pH 9.0) to urocanic acid for 16 days of continuous operation.The scope of this carbodiimide assisted immobilization procedure has been investigated for a series of microorganisms and a variety of carboxylate functionalized supports.
Assimilation of liquid hydrocarbon by microorganisms. II. Growth kinetics
Authors: Miura Yoshiharu , Okazaki Mitsuo , Murakawa Shin‐Ichi , Hamada Shin‐Ichiro , Ohno Kyoko 
Published: December 2004

AbstractThe growth kinetics of a microorganism with high affinity for liquid hydrocarbon which has a low solubility in water was investigated for Candida intermedia IFO 0761 in our previous work.6 The microorganism contained a hydrocarbon pool in and/or on the cell. The transfer of water‐soluble substrates to the cell was not the rate‐limiting step in the growth of C. intermedia accompanied by clump formation with liquid hydrocarbon. The operating conditions necessary for the oxygen supply for the growth were adequate for the growth of C. intermedia on n‐tetradecane. The saturation kinetics was valid for the specific growth rate of C. intermedia and specific concentration of hydrocarbon per unit cell mass; the specific growth rate was expressed by the following equation:
Desorption of carbon dioxide from fermentation broth
Authors: Yagi Hideharu , Yoshida Fumitake 
Published: December 2004

AbstractRates of CO2 desorption from fermentation broths under actual operating conditions were determined by measuring the CO2 partial pressure in the exit gas. The concentrations of CO2 physically dissolved in the broths were measured by the so‐called tubing method. Values of kLa for CO2 desorption calculated from these values agreed well with the kLa values for oxygen absorption corrected for the difference in gas diffusivities. The dissolved CO2 concentration in the broth, which seems to bean important operating parameter, can easily be estimated from the CO2 partial pressure in the exit gas, a more easily measurable quantity, if the kLa value is known. For a given value of kLa, assumption of perfect mixing or plug flow in the gas phase made little difference in the calculated values of the dissolved CO2 concentration, indicating that the gas phase was probably in between perfect mixing and plug flow.In industrial fermentors, the CO2 partial pressure in the exit gas can practically be assumed to be in equilibrium with the dissolved CO2 concentration.
Continuous manufacture of yogurt. I. Optimal conditions and kinetics of the prefermentation process
Authors: Driessen F. M. , Ubbels J. , Stadhouders J. 
Published: December 2004

AbstractThe principles of a method for the continuous manufacture of yogurt, based upon a two stage system, are given. The first stage, the prefermentation of milk at 45°C to a pH of 5.7, is described.The limitations of this continuous prefermentation are experimentally determined. No change in the balance of the yogurt bacteria, Lactobacillus bulgaricus and Streptococcus thermophilus, was observed. A mathematical approach is given for starting and stopping the process.
Methane fermentation of brewery by‐products
Authors: Keenan John D. , Kormi Iraj 
Published: December 2004

AbstractA laboratory‐scale research program was undertaken to investigate the kinetics of the mesophilic (37°C) anaerobic digestion of brewery industry by‐product. The purpose was to develop data for the design and operation of full‐scale units which could be used to generate methane fuel gas from these materials. This is important because the brewery industry has been susceptible to shortages of natural gas in recent years. The minimum SRT is 2.3 days, although for design purposes as much as ten days is recommended. The biomass yield is 0.512 g volatile suspended solids (VSS)/g volatile solids (VS) or 0.421 g VSS/g chemical oxygen demand (COD). The maintenance requirement is 0.052 g VS/g VSS per day or 0.061 g COD/g VSS per day. The specific methane yield is 2.51 liter/g VSS, and the methane productivity is 0.32–0.41 liter/g dry substrate added or 0.69–0.91 liter/g destroyed. The maximum loading rate for which substrate inhibition is not observed is 6 g dry substrate added per liter per day. The results of the entire program indicate that processing brewery by‐product in this manner is both technically feasible and economically attractive.
Dynamic measurement of the volumetric mass transfer coefficient in agitated vessels: Effect of the start‐up period on the response of an oxygen electrode
Authors: Linek V. , Vacek V. 
Published: December 2004

AbstractThe response of a polarographic oxygen electrode to a step change and to an exponential change in bulk oxygen concentration was studied theoretically and experimentally for the case where there is a significant liquid film resistance at the outerside of the membrane‐covered electrode. The probe response has been described considering the start‐up period of the concentration changes (the period of time that will elapse before the new concentration level is established and/or before the volumetric mass transfer coefficient kLa regains its steady‐state value after the gas supply is opened to the fermentor). A linear change of the pertinent characteristics is assumed during this start‐up period. It is shown that a substantial error could be introduced by neglecting the start‐up period for cases frequently occurring in practice. In addition, the dependences of the probe response on the direct contact of bubbles with an electrode and on the fluid flow field around it were discussed.
Rapid ethanol fermentations using vacuum and cell recycle
Authors: Cysewski Gerald R. , Wilke Charles R. 
Published: December 2004

AbstractCell recycle and vacuum fermentation systems were developed for continuous ethanol production. Cell recycle was employed in both atmospheric pressure and vacuum fermentations to achieve high cell densities and rapid ethanol fermentation rates. Studies were conducted with Saccharomyces cerevisiae (ATCC No. 4126) at a fermentation temperature of 35°C. Employing a 10% glucose feed, a cell density of 50 g dry wt/liter was obtained in atmospheric‐cell recycle fermentations which produced a fermentor ethanol productivity of 29.0 g/liter‐hr. The vacuum fermentor eliminated ethanol inhibition by boiling away ethanol from the fermenting beer as it was formed. This permitted the rapid and complete fermentation of concentrated sugar solutions. At a total pressure of 50 mmHg and using a 33.4% glucose feed, ethanol productivities of 82 and 40 g/liter‐hr were achieved with the vacuum system with and without cell recycle, respectively. Fermentor ethanol productivities were thus increased as much as twelvefold over conventional continuous fermentations. In order to maintain a viable yeast culture in the vacuum fermentor, a bleed of fermented broth had to be continuously withdrawn to remove nonvolatile compounds. It was also necessary to sparge the vacuum fermentor with pure oxygen to satisfy the trace oxygen requirement of the fermenting yeast.
Considerations in predicting phenotypic modifications in amino acid profiles of total cell protein of microorganisms
Authors: Alroy Yair , Tannenbaum Steven R. 
Published: December 2004

AbstractA mathematical model is presented that describes the concentration of an amino acid in total cell protein as a function of its concentration in individual cell proteins or in sets of cell proteins. The resulting equation makes it possible to calculate how the makeup of cell proteins must change to obtain a specified alteration in the content of an amino acid in the total cell protein. It is recognized that protein species or sets of proteins that are distinguished by being richer or poorer in a key amino acid than the overall protein must undergo considerable variations in content. The necessary extent of these shifts suggests that the amino acid composition of total cell protein is not likely to be affected significantly by variations in the cultivation conditions.
A new approach to preparative enzymatic synthesis
Authors: Klibanov Alexander M. , Samokhin Gennady P. , Martinek Karel , Berezin Ilya. V. 
Published: December 2004

AbstractA new approach to preparative organic synthesis in aqueous–organic systems is suggested. It is based on the idea that the enzymatic process is carried out in a biphasic system “water–water‐immiscible organic solvent.” Thereby the enzyme is localized in the aqueous phase—this eliminates the traditional problem of stabilizing the enzyme against inactivation by a nonaqueous solvent. Hence, in contrast to the commonly used combinations “water–water‐miscible organic solvent,” in the suggested system the content of water may be infinitely low. This allows one to dramatically shift the equilibrium of the reactions forming water as a reaction product (synthesis of esters and amides, polymerization of amino acids, sugars and nucleotides, dehydration reactions, etc.) toward the products. The fact that the system consists of two phases provides another very important source for an equilibrium shift, i.e., free energies of the transfer of a reagent from one phase to the other. Equations are derived describing the dependence of the equilibrium constant in a biphasic system on the ratio of the volumes of the aqueous and nonaqueous phases and the partition coefficients of the reagents between the phases. The approach has been experimentally verified with the synthesis of N‐acetyl‐L‐tryptophan ethyl ester from the respective alcohol and acid. Porous glass was impregnated with aqueous buffer solution of chymotrypsin and suspended in chloroform containing N‐acetyl‐L‐tryptophan and ethanol. In water (no organic phase) the yield of the ester is about 0.01%, whereas in this biphasic system it is practically 100%. The idea is applicable to a great number of preparative enzymatic reactions.
Dynamics of a chemostat in which two organisms compete for a common substrate
Authors: Aris R. , Humphrey A. E. 
Published: December 2004

AbstractWhen two organisms compete for a given substrate without preying on one another, the possible steady states depend on the relative disposition of the two growth curves and the position of the point (Z,θ), whose coordinates are the nutrient feed concentration and dilution rate. It is shown how the stability of each steady state can be understood and qualitative phase portraits can be drawn for each of the 31 distinct types of situations.
Theoretical conversion yields for penicillin synthesis
Authors: Cooney C. L. , Acevedo F. 
Published: December 2004

AbstractThe efficiency of conversion of the carbon‐energy source to product is of primary importance in many fermentation processes. In order to assess the efficiency of a process, one must know how close the actual conversion yield is to the theoretical maximum. Theoretical conversion yields are useful, therefore, as guides in improving a process. This knowledge is particularly important today because the cost of raw materials is rapidly rising. In this study, the biochemical pathway of penicillin synthesis was used to estimate the theoretical yield of penicillin from glucose, ammonia, and sulfate. These values are compared with experimental data from the literature. An analysis of the role of glucose in the synthesis of cell mass and penicillin and in the maintenance of cells makes it possible to assess the efficiency of carbon‐source utilization and to direct further advances in penicillin fermentations.
Modeling and simulation of oxygen transfer in airlift fermentors
Authors: Ho Chester S. , Erickson Larry E. , Fan L. T. 
Published: December 2004

AbstractA mathematical model for simulation of oxygen transfer in airlift fermentors is presented. The airlift fermentor is represented by a number of interconnected compartments, each of which is assumed to be well mixed. In the annular region, the model includes both upflow and downflow for the gas phase. The model contains several adjustable parameters through which important hydrodynamic effects affecting oxygen transfer are incorporated. The effect of hydrostatic pressure is also included in the model. The model is simple enough to be used in design studies and it can be easily adapted to other airlift system configurations. The simulation results show good qualitative agreement with available experimental results.
Disintegration of microorganisms in an industrial horizontal mill of novel design
Authors: Rehacek J. , Schaefer J. 
Published: December 2004

AbstractA continuous high‐speed horizontal colloid mill of novel design for use in the microbiological and food industries was tested for the disintegration of cells of Saccharomyces cerevisiae and Candida utilis. The mill consists of a horizontal vessel with round or oval cross sections fitted with a high‐speed longitudinal agitator shaft on which are mounted disk agitators, alternating radially and obliquely to the shaft. The mill is partly filled with freely moving grinding elements which, during a continuous operation, are maintained in the vessel by a vibrating annular slot separator. Highly efficient cooling is provided by circulation of cooling fluid through a jacket surrounding the vessel as well as through the agitator shaft and disks. The radial agitator disks impart a radial motion to the grinding elements, while the oblique disks give rise to the axial movement of a substantial part of the elements. The crossing of paths thus achieved gives the mill a very high efficiency. Using a mill of 20 liter nominal capacity, the effects of agitator design, agitator speed, flow rate, and concentration of the cell suspension on the disintegration efficiency and heat production were studied. Ninety per cent of S. cerevisiae cells in a 15% suspension could be broken at a residence time of 2.5 min. The temperature rise did not exceed 8° C. The corresponding figure for C. utilis was 84%. The maximal flow rate was 400 liter/hr. Extrapolation indicates that available industrial mills of 300 liter capacity based on the same design can handle flows of 2000 liter/hr.
Microbial electrode BOD sensors
Authors: Karube Isao , Matsunaga Tadashi , Mitsuda Satoshi , Suzuki Shuichi 
Published: December 2004

AbstractTwo different types of biochemical oxygen demand (BOD) sensors using microbial electrodes were prepared. First, a microbial electrode using the bacteria–collagen membrane and oxygen electrode was used for the determination of BOD. When the electrode was inserted in a sample solution containing glucose and glutamic acid (model waste water), the current of the electrode decreased markedly with time until a steady state was reached. A linear relationship was observed between the steady state current and the concentration of the standard solution containing glucose–glutamic acid or the BOD of the solution. The BOD of industrial waste waters can be estimated within 15 min by using the microbial electrode. No decrease in current output was observed over a ten day period. The reproducibility was determined using the same sample (10% of the standard solution) and was found to be 26.2 ± 2.0 μA (7.5% of the relative standard deviation). Next, a biofuel cell utilizing microbial electrode (immobilized Clostridium butyricum–platinum electrode) was applied to the estimation of the BOD of waste waters. The current of the biofuel cell was decreased markedly with time until a steady state was reached. The steady state current was in all cases attained within 30–40 min at 37°C. A linear relationship was obtained between the steady state current and BOD. The BOD of industrial waste waters can be estimated by using the biofuel cell. Relative error of the BOD estimation was within ±10%. The current output of the biofuel cell was almost constant for 30 days.