bluuebunny/crossref_metadata_2025 huggingface dataset:
Recovery of biological materials through ultrafiltration
Authors: Wang Daniel I. C. , Sinskey Anthony J. , Sonoyama Takayasu
Published: December 2004

Experiments were performed on a cellulose acetate ultrafiltration membrane (HF‐200, ABCOR Inc., Cambridge, Mass.) to test its efficacy in concentrating and purifying a crude enzyme (trypsin) preparation. Studies were also made to determine the influence of inorganic salts, pressure, and temperature on the rate of ultrafiltration for this membrane. The results showed reductions in the rates will be encountered due to the presence of inorganic salts. However, the reduced rates were still sufficiently high to make this method extremely attractive. Operating at filtration pressures above 75 psi at, 20 to 30°C for this membrane does not show any beneficial effect in terms of ultrafiltration rates. However, at 10°C there were continual increases in the filtration rates up to 100 psi. Concentration and purification studies with trypsin yielded a concentration factor of 8.35 and a purification factor 2.35. It was shown concretely that the purification of the enzyme was due to the passage of low molecular weight proteins (below 20,000) through the membrane. Enzyme activity slightly greater than 90% was obtained: 70% was found in the concentrate and 20% in the filtrate. It is concluded that membrane ultrafiltration is an ideal simple, rapid, and economical method for the recovery of biological active substances.
An improved, totally automated antibiotic bioassay machine
Authors: Burns Donald A. , Williams Paul R. , Hansen Gary D.
Published: December 2004

A number of improvements have been made in a totally‐automated antibiotic bioassay machine previously described. The new machine accepts unmeasured, untreated, opaque suspensions of fermentation beers three times faster (120 samples per hour) and supplies printed potencies sooner (in just over two hours). Whereas the original machine employed a self‐cleaning filter and used disposable two milliliter beakers, this version involves a batch‐dialysis scheme for effecting sample purification, and provides for automated cleaning of incubation chambers.

In operation, a measured, portion of thoroughly‐mixed fermentation beer is automatically diluted and transferred into one side of an incubation chamber, the two halves of which are separated by a dialysis membrane. The other half is filled with inoculated media. During the two hour incubation at 37°, dialyzable antibiotic limits growth of the inoculum in proportion to its concentration. After incubation, the turbidity of the inoculum is simultaneously read by an online computer and plotted on a strip chart recorded. The computer suplies printed potency values and sample identification on site, while the recording provides the operator with an analog record of turbidity. Fiber optics are employed in the turbidmetric readout, and an electric typewrite provides the printout.
Multiple immobilized enzyme reactors: Determination of pyruvate and phosphoenolpyruvate concentrations using immobilized lactate dehydrogenase and pyruvate kinase
Authors: Newirth T. L. , Diegelman M. A. , Pye E. K. , Kallen Roland G.
Published: December 2004

Lactate dehydrogenase (LDH) and pyruvate kinase (PK), immobilized on solid glass beads by diazotization, were used in packed bed reactors to analyze for both pyruvate (PYR) and phosphoenolpyruvate (PEP) through the disappearance of β‐nicotinamide adenine dinucleotide (NADH) monitored spectrophotometrically at 340 nm. Packed bed reactors containing PK and/or LDH were also capable of monitoring continuously varying concentrations of adenosine‐5′‐diphosphate (ADP), PEP, and PYR. The immobilized enzymes (∼40 μg/g glass) retained about 4% of the activity of the soluble enzymes. Preparations of immobilized LDH and PK exhibited enhanced stability when maintained in the presence of β‐mercaptoethanol and NADH or EDTA, respectively, and were shown to regain 75% of the original activity after four months storage at 4°C.
Fungal cultures and culture mediums for the production of cellulase
Authors: De Menezes Hilary C. , De Menezes Tobias J. B. , Boas Herval Villas
Published: December 2004

Cellulase production by strains of Myrothecium verrucaria, Stachybotrys atra and Trichoderma viride was examined. Myrothecium verrucaria was found to give the greatest yields. A variety of media were examined as potential substrates for the industrial production of cellulase. The salts content of the medium was varied and was found to affect cellulase production. Glucose, carboxymethylcellulose (CMC), filter paper and three industrial wastes were examined as possible cellulase inducers. Filter paper was found to be the most effective, followed by sugar cane bagasse and CMC.
Equations of substrate‐limited growth: The case for blackman kinetics
Authors: Dabes J. N. , Finn R. K. , Wilke C. R.
Published: December 2004

A simplified model of cell metabolism, consisting of a series of linked reversible enzymatic reactions dependent on the concentration of a single external substrate has been developed. The general mathematical solution for this system of reactions is presented. This general solution confirms the concept of a rate‐limiting step, or “master reaction”, in biological systems as first proposed by Blackman. The maximum rate of such a process is determined by, and equal to, the maximum rate of the slowest forward reaction in the series.

Of practical interest in modeling the growth rate of cells are three cases developed from the general model. The simplest special case results in the Monod equation when the maximum forward rate of one enzymatic reaction in the cell is much less than the maximum forward rate of any other enzymatic reactions.

More realistic is the case where the maximum forward rates of more than one enzymatic reaction are slow. When two slow enzymatic reactions are separated from each other by any number of fast reactions that overall can be described by a large equilibrium constant, the Blackman form results:

and

A third case is that in which two slow enzymatic steps are separated by an equilibrium constant that is not large. Unlike the Monod and Blackman forms, which contain only two arbitrary constants, this model contains three arbitrary constants:

The Monod and Blackman forms are special cases of this three constant form.

In comparing equations with two arbitrary constants the Monod equation gave poorer fit of the data in most cases than the Blackman form. It is concluded that workers modeling the growth of microorganisms should give a t least as much consideration to the Blackman form as is given to the Monod equation.
The effect of controlled feeding of glycerol on β‐galactosidase production byEscherichia coliin batch culture
Authors: Gray Peter P. , Dunnill Peter , Lilly Malcolm D.
Published: December 2004

A mutant ofE. coliconstitutive for β‐galactosidase has been grown in batch culture with the carbon source, glycerol, fed at various fixed rates to the culture. High feeding rates where growth was only slightly restricted gave final enzyme levels similar to those obtained in cultures where all the glycerol was added initially. Low feeding rates resulted in breakdown of the β‐galactosidase formed and gave reduced final levels of the enzyme.
Theory of the kinetics of reactions catalyzed by enzymes attached to membranes
Authors: Kobayashi Takeshi , Laidler Keith J.
Published: December 2004

A theoretical treatment has been worked out for the kinetics of solid‐supported enzyme systems, with diffusive and electrostatic effects taken into account. A utilization factor, defined as the ratio of the actual reaction rate to the rate of substrate consumption in the outer solution, is defined, and equations to evaluate the utilization factor are given for five kinetic conditions: (a) Michaelis‐Menten behavior, (b) substrate inhibition, (c) product inhibition (competitive), (d) product inhibition (noncompetitive), and (e) product inhibition (anticompetitive). When the solid‐supported enzymes obey a Michaelis‐Menten relationship, an equation for the apparent Michaelis constant is given and a criterion for insignificant diffusion effects is shown. A substrate‐inhibited enzyme reaction may display multiple steady‐state behavior, and a criterion for uniqueness is presented. In the case of product‐inhibited enzyme reactions, the utilization factor is always less than that which corresponds to a Michaelis‐Menten relationship. Equations to evaluate the apparent Michaelis and inhibition constants are given.
Immobilization of enzymes on magnetic particles
Authors: Van Leemputten E. , Horisberger M.
Published: December 2004

Trypsin (EC 3.4.4.4) was immobilized in low yield on aminoalkylsilylated magnetite (Fe3O4). Better results were obtained when trypsin was immobilized by crosslinking with glutaraldehyde on magnetite. The preparation contained 36 mg protein/g magnetite and the enzyme retained 46% and 11% of esterase and proteolytic activity. Immobilized trypsin was more heat stable than trypsin. Invertase (β‐D‐fructofuranoside fructohydrolase, EC 3.2.1.26) was cross‐linked on magnetite with glutaraldehyde in low yield due to the inactivation of the enzyme. However in the presence of 1% sucrose, the total activity recovered was 79% of the initial activity and the preparation contained 4.4 mg/g of active invertase. Immobilized invertase was less active than invertase when acting on oligosaccharides of the raffinose family. The immobilized enzymes could be easily recovered, from solutions or suspensions, magnetically.
Reduction and separation of nitrate and nitrite by liquid membrane‐encapsulated enzymes
Authors: Mohan Raam R. , Li Norman N.
Published: December 2004

Purified enzymes encapsulated in liquid surfactant membranes have been shown to retain their catalytic activity. In general, previous work on encapsulation has been confined to single enzymes. The system has now been extended to encapsulate a bacterial cell‐free homogenate. Liquid membrane‐encapsulated bacterial cell‐free homogenate reduces effectively NO3− to NO2− and other nitrogen compounds of lower oxidation state. This technique of removing nitrates and nitrites may have application in waste‐water treatment. Also, it has been shown that encapsulated cell‐free homogenate does not leak and there is no absorption of the substrate onto the liquid surfactant membrane surfaces. The reduction in the reaction rates is discussed in terms of solubility of the substrate and the rate of permeation of the substrates through the liquid surfactant membrane.
Preparation of an immobilized two‐enzyme system, β‐amylase‐pullulanase, to an acrylic copolymer for the conversion of starch to maltose. I. Preparation and stability of immobilized β‐amylase
Authors: Mårtensson Kaj
Published: December 2004

β‐Amylase (EC 3.2.1.2), obtained from barley, was chemically attached to a crosslinked copolymer of acrylamide‐acrylic acid using a water‐soluble carbodiimide. The derivative showed 23% β‐amylase activity in relation to that of free enzyme with a coupling yield of 40% based on the amount of added β‐amylase. In order to find optimal coupling conditions, the effect of pH and different carbodiimide concentrations was investigated. The enzymic activity associated with different β‐amylase concentrations was further outlined. A slightly increased operational stability for the enzyme upon immobilization was observed. Markedly improved operational stability has been obtained by coupling in the presence of reduced glutathione of bovine serum albumin.
Preparation of an immobilized two‐enzyme system, β‐amylase‐pullulanase, to an acrylic copolymer for the conversion of starch to maltose. II. Cocoupling of the enzymes and use in a packed bed column
Authors: Mårtensson Kaj
Published: December 2004

β‐Amylase (EC 3.2.1.2) and pullulanase (EC 3.2.1.9) have been covalently bound in a two‐enzyme system to a crosslinked copolymer of acrylarmide‐acrylic acid by using a water‐soluble carbodiimide. The coupling yields based on the amounts of added β‐amylase and pullulanase were 40% and 38%, respectively, with residual enzymic activities of 22% and 32% of those of free enzymes. A markedly increased operational stability was observed for the immobilized two‐enzyme system compared to the free enzymes in solution. In order to find optimal operational conditions the influence of different pH values and temperatures on the conversion process was investigated. The action of the immobilized β‐amylase‐pullulanase derivative on partially hydrolyzed starch (DE 3.4–10.7) in a packed bed column was studied. Analysis of the product was performed using gas‐liquid chromatography.
Continuous hydrocarbon fermentation with colloidal emulsion feed. A kinetic model for two‐liquid phase culture
Authors: Yoshida Fumitake , Yamane Tsuneo
Published: December 2004

Candida tropicalis was cultured in a chemostat‐type fermentor with n‐hexadecane, dispersed in water as submicron droplets, as the only carbon substrate. The emulsion as well as the aqueous medium were fed continuously into the fermentor. A Monod‐type equation can correlate the specific group rate in the continuous fermentor with the concentration of submicron droplets. The same equation can also be fitted to the data for the conventional‐type batch culture in the same fermentor in which an oil phase as well as an aqueous phase existed, if the hydrocarbon concentration in the aqueous phase excluding oil drops is employed as the substrate concentration. This demonstrates that Candida tropicalis takes up only submicron droplets of n‐hexadecane as the carbon substrate.
Preparation of immobilized lactase. Continued studies on the enzymatic hydrolysis of lactose
Authors: Weetall H. H. , Havewala N. B. , Pitcher W. H. , Detar C. C. , Vann W. P. , Yaverbaum S.
Published: December 2004

A soluble fungal lactase (lactase‐W) of greater activity that the previously available fungal lactase (lactase‐M) has been covalently coupled to ZrO2‐coated porous glass particles and 1 mm diameter porous TiO2 particles. The immobilized lactase‐W appears to give results similar to the lactase‐M except for the operational half‐life. At 30°C the half‐life of the lactase‐M appears to exceed that of the lactase‐W by approximately 100 days under operational conditions.
Kinetics of formation of humic substances in activated sludge systems and their effect on flocculation
Authors: DeWalle F. B. , Chian E. S. K
Published: December 2004

Humic substances were isolated during batch aeration studies with activated sludge and a complex waste source, by using concentration and separation techniques that employ reverse osmosis, ultrafitration, and gel permeation chromatography. The study suggests that the formation of high molecular weight humic substances may occur after the removal of the readily available carbon source. The amount of refractory material finally present in the solution will depend on its adsorptive properties toward bacterial cells. The adsorptive characteristics may be determined by the magnitude of the carbohydrate fraction present in the humic substances. If the carbohydrate content decreases, adsorption onto the cells may decrease resulting in an impairment of both the floe formation and settleability of the sludge floes. Decreased adsorption will result in a higher total organic carbon content and an increase in color bearing materials in the effluent.
Temperature effects on anaerobic fermentation of domestic refuse
Authors: Pfeffer John T.
Published: December 2004

Anaerobic fermentation of organic solid waste can provide a significant source of fuel gas (methane). Application of this process requires a better understanding of the kinetics of the biological system. The literature is replete with kinetic studies of this process as applied to waste solids from water pollution control systems. Much of this work has been conducted in the mesophilic temperature range. Increased temperatures yield higher reaction rates that will improve the economics of the process. The rate limiting step in the fermentation of refuse is the hydrolysis of the complex organic solids, in particular cellulose. Cellulose is a major component of the refuse. A laboratory study employing domestic refuse has shown the effect of temperature on the rate of methane fermentation. The optimum mesophilic temperature was found to be 42°C, while the optimum thermophilic temperature was at least 60°C. No data was obtained beyond the 60°C temperature. Reaction rate constants are presented for anaerobic fermentation of domestic refuse. Because of the characteristics of the substrate it−was not possible to obtain the necessary measurements for evaluation of constants in the Monod model. An overall system constant was developed.
External and internal diffusion in heterogeneous enzymes systems
Authors: Horvath Csaba , Engasser Jean‐Marc
Published: December 2004

The intrusion of diffusion in heterogeneous enzyme reactions, which follow. Michaelis‐Menten kinetics, is quantitatively characterized by dimensionless parameters that are independent of the substrate concentration. The effects of these parameters on the overall rate of reaction is illustrated on plots commonly employed in enzyme kinetics. The departure from Michaelis‐Menten kinetics due to diffusion limitations can be best assessed by using Hofstee plots which are also suitable to distinguish between internal and external transport effects. A graphical method is described for the evaluation of the reaction rate as a function of the surface concentration of the substrate from measured data.
Maximal exponential growth rate and yield of E. coli obtainable in a bench‐scale fermentor
Authors: Bauer S. , Shiloach J.
Published: December 2004

Oxygen supply is one of the main factors which influences aerobic cell growth in a fermentor. Maximal rates at which E. coli can grow on glucose as carbon source under various limiting oxygen‐supply conditions were determined in a bench‐scale fermentor. Culture conditions are described which gave yields of about 38 g dry cells per liter medium.
Gel entrapped enzymes: Kinetic studies of immobilized β‐galactosidase
Authors: Hinberg I. , Korus R. , O'Driscoll K. F.
Published: December 2004

β‐galactosidase from E. coli (β‐D‐galactose galactohydrolase, EC 3.2.1.23) has been entrapped in a crosslinked 2‐hydroxyethyl methacrylate gel with a 35% retention of activity. The kinetic behavior of the gel‐entrapped enzyme has been studied in a recirculation reactor system, the substrate being o‐nitrophenyl‐βhyphen;D‐ galactopyranoside. Kinetic constants were determined for particle sizes ranging from 69 to 231 μm in diameter and compared to those of the free enzyme. External diffusion effects were eliminated by operating at high recirculation flow rates. A fourfold increase in Km(app) was observed for the 231 μm particles, consistent with existing theoretical treatments for internal diffusion effects.

An Arrhenius plot of rate data showed significant curvature at higher temperatures, which was attributed to the effects of internal diffusion. The pH–activity profile of the gel‐entrapped enzyme was bell‐shaped at high substrate concentration and, in contrast to the free enzyme, could be fitted to the titration curve of two ionizable groups, a basic group having a pK of 8.6. The gel‐entrapped enzyme had a higher pH optimum and retained a larger percentage of its maximal activity at alkaline pH than the free enzyme; its pH stability at high pH was also much better.

The thermal stability of the gel‐entrapped enzyme was studied and found to be 14 days at 22°C and 65 min at 45°C.
The functional role of lipids in hydrocarbon assimilation
Authors: Hug H. , Blanch H. W. , Fiechter A.
Published: December 2004

The yeast Candida tropicalis utilizes both glucose and hydrocarbons as sole carbon sources. When grown on hydrocarbons, the cells contain twice as much lipid as when grown on glucose. In transient continuous culture experiments, following a substrate change from glucose to hexadecane, an adaption phase occurred. During this phase the lipid concentration per cell increased greatly. It is proposed that a high cellular lipid concentration is necessary for hydrocarbon assimilation, and this is not just a reflection of the lipophilic nature of the substrate.
Reduction of contamination in an industrial fermentation plant
Authors: Bartholomew W. H. , Engstrom D. E. , Goodman N. S. , O'Toole A. L. , Shelton J. L. , Tannen L. P.
Published: December 2004

Information is presented concerning revisions of the fermentation air system equipment which improved the sterility situation in the production of monosodium glutamate.

Basically, the revision were a relocation and elevation of the intake to the air compressors and installation of a retention chamber after the compressors to take advantage of the heat of compression.

The extended high temperature retention ensures sterile air to the final air filter before the fermentor. Contamination losses—mainly from phage—have been materially reduced relative to the level prevailing before the change.
Enzyme catalysis in the presence of nonaqueous solvents using chloroperoxidase
Authors: Cooney Charles L. , Hueter John
Published: December 2004

Studies exploring the effect of two nonaqueous solvents on enzyme activity were done using chloroperoxidase as a model system. Chloroperoxidase produced by Caldariomyces fumago is a bifunctional enzyme with halogenating activity at pH 3 and peroxidation activity at pH 5 to 6. Methanol affected both of these activities similarly. Furthermore, methanol and the halogen acceptor, monochlorodimedon, competitively inhibit the reaction. These results are discussed in terms of the site of action of methanol. At 10% methanol concentration, the enzyme retained up to 33% of its activity depending on the monochlorodimedon concentration. Dimethylsulfoxide at 10% concentration permitted up to 47% retention of activity. Its effects on the enzyme are more complex than methanol and are discussed in terms of a transitory inactivation of the enzyme.
Recovery of erythropoietin from anemic sheep plasma
Authors: Hancher C. W. , Hall R. F. , Ryon A. D. , Kelmers A. D.
Published: December 2004

A method is described for the large‐scale preparation of erythropoietin from anemic sheep plasma. DEAE‐cellulose and carboxymethylcellulose column chromatography was used to prepare Step II erythropoietin. A total of 168 sheep yielded 499 liters of plasma from which 323,000 IU of Step II erythropoietin was obtained.
An enzyme rate equation for the overall rate of reaction of gel‐immobilized glucose oxidase particles under buffered conditions. II. Two limiting substrates
Authors: Atkinson B. , Lester D. E.
Published: December 2004

The overall rate of reaction of gel‐immobilized glucose oxidase particles in buffered media has been investigated theoretically under two substrate diffusion limited conditions by the numerical solution of the diffusion equations. It has been found that the Enzyme Rate Equation (Atkinson and Lester), Biotechnol. Bioeng., 16, 1299 (1974), together with an analytical solution which describes the asymptotic conditions associated with a large particle size, provides an adequate estimation of the values resulting from the numerical solution outside the region of the parameter space defined by 0.4 < Mg′, M0′ < 10.

When the dimensionless parameter (B0′/Bg′)(Mg′2/M0′2) is greater than unity the overall rate of reaction is limited principally by the external concentration and when the parameter has a value less than unity, by the external oxygen concentration.

The results are generally applicable to enzymes whose kinetics are similar to those of glucose oxidase or for which the equation describing glucose oxidase kinetics provides an adequate curve‐fit of experimental data.
Immobilized enzyme catalysis with reaction‐generated pH change
Authors: Bailey J. E. , Chow Mary T. C.
Published: December 2004

Many enzyme‐catalyzed reactions involve the liberation or consumption of hydrogen ions. In this paper a mathematical model is employed to investigate how such reactions behave when the enzyme is immobilized. Shifted pH optima, disappearance of an optimum pH, insensitivity to bulk pH, and very large effectiveness factors are some of the phenomena which appear as a result of pH coupling between the reaction and the enzyme's activity. Several of the qualitative features revealed by the model are consistent with earlier experimental observations. In addition, preliminary guidelines for optimal choice of enzyme support are suggested.
An annular bound‐enzyme reactor
Authors: Emery A. , Sorenson J. , Kolarik M. , Swanson S. , Lim H.
Published: December 2004

A column reactor with an annular cross section was formed by rolling up DEAE cellulose paper and a screening spacer. Glucoamylase was attached by ion adsorption. For the spacer used, pressure drop was very low, suggesting that this form may be useful with feed streams that are not completely particle‐free. Tests of this reactor at the high substrate concentrations characteristic of commercial reactors showed very little diffusional resistance, exhibiting zero‐order behavior over most of the concentration range. At low concentrations, the reactor had an apparent “half‐order” behavior caused by diffusional limitation in the paper. In this range, flow rate influenced the reaction rate, showing that mass transfer in the main stream also is a contributing factor in this range. Because of the high concentrations and the low Michaelis constant (0.0011 M) the reactor does not show first‐order behavior, even at very high conversions. The design of a plant‐scale reactor was formulated from these data. The increase in the quantity of enzyme necessary to compensate for the effects of diffusion was only a few percent.

Two reactors were formed with sheets nonporous to the enzyme, binding the enzyme with cyanogen bromide after forming the reactor. The amount of enzyme bound was about one monolayer, and there appeared to be no diffusional limitations, even at low substrate concentrations.
Assessment of methanogenie activity in anaerobic digestion: Apparatus and method
Authors: Van Den Berg L. , Lentz C. P. , Athey R. J. , Rooke E. A.
Published: December 2004

An apparatus is described for the rapid measurement and recording of methanogenic activity in anaerobic fermentations, and its application is demonstrated in the evaluation of the anaerobic contact process, using pear waste. The method is based on recording the rate of manometer liquid displacement in a Warburgtype vessel by means of optical sensors, appropriate electronic circuitry, and an event marking recorder or time‐interval printer. Optimum conditions for measuring methanogenic activity included a pH of 6.7–6.9, a final phosphate buffer concentration of 0.07–015M, and formic and acetic acid contents of over 500 and 200 mg/liter, respectively. In comparisons of fermenter liquid and settled effluent, methanogenic activity can be assumed to be proportional to the number of methane formers present. The apparatus should be generally useful in recording rates of gas production or consumption.
Enzymatic hydrolysis of waste cellulose
Authors: Mandels Mary , Hontz Lloyd , Nystrom John
Published: December 2004

Waste cellulose was a suitable carbon source for cellulose production by Trichoderma viride. The enzyme can be produced in submerged fermentation using newspaper as a growth substrate. A variety of pure and complex cellulosic materials were hydrolyzed by culture filtrates. Saccharification of 5% slurries after 48 hr ranged from 2–92%. The rate and extent of hydrolysis was controlled by degree of crystallinity, particle size, and presence of impurities. Newspaper was used to evaluate methods for the pretreatment of substrate. The best pretreatment was ball milling which gave good size reduction, maximum bulk density, and maximum susceptibility. Hammer milling, fluid energy milling, colloid milling, or alkali treatments were less satisfactory. Dissolving cellulose in cuprammonium, or carbon disulfide (Viscose) and then reprecipitating gave a susceptible, but low bulk density product. However the susceptibility was lost if the substrate was dried. Because of costs, low bulk density, necessity of keep ing the substrate wet, and generation of chemical waste streams dissolving cellulose to increase reactivity does not seem a practical approach.

Cellulose fractions separated from municipal trash or agricultural residues such as milled fibres from bovine manure are promising substrates for conversion.
The influence of alkali and heat treatment on yeast protein
Authors: Lindblom Marianne
Published: December 2004

The soluble components in disintegrated cells of Saccharomyces cereivisiae have been characterized by means of extraction, centrifugation, dialysis, and gel filtration. The influence of alkali and heat treatment on the protein and RNA in the soluble fraction from disintegrated yeast cells and on functional properties of protein concentrates have been studied.

After water extraction and centrifugation at 100000 g 42% of the nitrogen containing components of the disintegrated cells were recovered in the supernatant. By extraction at pH 11.5 an additional 31% of the nitrogen was solubilized. Half of the water‐soluble nitrogen‐containing components has a molecular weight lower than 5000. In the water‐ and alkali‐soluble fractions about 80% of each amino acid was recovered

The water‐soluble protein was separated into 3 fractions by gel filtration on Sephadex G 200. The major portion of the protein had a molecular weight about 100,000. The amount of protein in this fraction was decreased after treatment at increasing pH and temperature. No degradation of protein to low molecular peptides occurred. The amount of RNA in the soluble fraction was only slightly influenced by alkali treatment and by heat treatment at pH 7.5 in the presence of 5% NaCl. RNA was not degraded to low molecular components of the treatments.

The solubility of protein concentrates decreased after treatment at alkaline pH and after heat precipitation.
Studies on aminoacylase immobilized on porous ceramic carriers
Authors: Weetall Howard H. , Detar Clarence C.
Published: December 2004

Aminoacylase was covalently coupled to several porous ceramic type carriers and studied for durability under operating conditions. These studies indicate that it should be possible to develop a commercially economic system based on ceramic carriers for the resolution of racemic mixtures of amino acids.
Preparation of an immobilized two‐enzyme system, β‐amylase–pullulanase, to an acrylic copolymer for the conversion of starch to maltose. III. Process kinetic studies on continuous reactors
Authors: Mårtensson Kaj
Published: December 2004

Kinetic studies on the parameters influencing the potential industrial application of an immobilized two‐enzyme system of β‐amylase and pullulanase for conversion of starch to a product with high maltose content, have been performed. The apparent Michaelis constant, the apparent product inhibitor constant, and the activation energy have been determined for the immobilized preparation and compared to the values for the corresponding soluble enzyme system. The catalytic activity of the immobilized enzymes was studied in a plug‐flow reactor and a continuous feed stirred tank reactor. Mathematical models for these reactors have been formulated and adapted to fit the experimental data. Comparisons of the reactor efficiencies were made and the conditions were found to be such as to favor the plug‐flow reactor. Results on operational stability tests at different temperatures and substrate concentrations are given.
Characterization and immobilization of E. coli (ATCC‐26) β‐galactosidase
Authors: Wondolowski M. V. , Woychik J. H.
Published: December 2004

The β‐galactosidase from Escherichia coli ATTCC‐26 was partially purified and characterized. It was found to be comparable to galactosidases from other E. coli strains in stability, pH and temperature maxima, and activity requirements, but it had a more favorable ratio of activity toward lactose versus synthetic substrates. The galactosidase was immobilized on porous glass beads by three covalent bonding methods. Kinetic data for the free and bound enzymes were determined using natural and synthetic substrates. Activity characteristics of the free and immobilized enzymes were comparable, however, the bound forms were less stable to heat.
Transient behavior of a continuous stirred tank biological reactor utilizing phenol as an inhibitory substrate
Authors: Chi C. T. , Howell J. A.
Published: December 2004

Transient experiments were conducted on a Pseudomomas utilizing phenol in a continuous culture by disturbing the influent substrate concentration and dilution rate. Two stable steady states existed for some ranges of the parameters. Highly damped oscillations were observed in approaching a new high conversion steady state or in returning to a new high conversion steady state following a small disturbance. When a large disturbance was applied there was a smooth (overdamped) approach to a new low conversion steady state.

The observed oscillatory behavior for small disturbances was predicted by a modified Powell‐Ierusalemskii bottleneck model, but could not be predicted by a Monod‐Haldane model; neither model was accurate for predicting the effect of large disturbances.

A constant wall growth factor was used to account for microbial film activity, and the existence of two stable states was directly due to the presence of the film.
Dense growth of aerobic bacteria in a bench‐scale fermentor
Authors: Bauer S. , Ziv E.
Published: December 2004

Escherichia coli B, Escherichia coli MRE 600, Escherichia coli K 12‐3300, Pseudomonas fluorescens, and Aerobacter aerogenes were grown exponentially in a bench‐scale fermentor to cell concentrations in the range of 20 to 41 g dry cells/liter at 30°C and 30 to 55 g dry cells/liter at 25°C. The high cell concentrations were achieved in a growth system previously described for growth of Escherichia coli W (Biotechnol. Bioeng., 16, 933 (1974); ibid. 17, 227 (1975)). Various enzyme activity levels in the high‐concentration cells were compared to those in cells grown in conventional low‐density cultures. No significant differences were found. The culture supernatants were found to be essentially free of high‐molecular weight metabolic or cell lysis products. Yield constants for glucose, nitrogen, oxygen, and phosphorus were also determined in the dense cultures and some of their relations to the growth conditions are discussed.
Hydrolysis of D‐galactosides in an open tubular lactase reactor
Authors: Ngo T. T. , Narinesingh D. , Laidler K. J.
Published: December 2004

Lactose (β‐galactosidase) was attached to the inner surface of nylon tubing. Tubes of various lengths were used to bring about the hydrolysis of o‐nitrophenyl‐β‐D‐galactoside and of lactose in skim milk. The results with the former substrate were analyzed in the light of a theoretical treatment of Kobayashi and Laidler (Biotechnol. Bioeng., 16, 99, 1974), with the conclusion that the reaction is intermediate between diffusion‐free and completely diffusion‐controlled behavior. The results with skim milk show that with a single 46 m tube and continuous circulation, 90% of the lactose is removed within 20 hr. A battery of ten such tubes, with single passage, at a flow rate of 2 cm/sec, would remove more than 99% of the lactose in less than 40 min.
The application of constant recycle solids concentration in activated sludge process
Authors: Bonotan‐Dura F. M. , Yang P. Y.
Published: December 2004

The applicability of the model derived by Ramanathan and Gaudy (Biotechnol. Bioeng., 11, 207, (1969)) for completely mixed activated sludge treatment holding the recycle solids concentration as a system constant was investigated using an actual industrial organic wastewater. Short‐term experiments were conducted at various dilution rates (1/8, 1/6, 1/4, 1/2, 1/1.5 hr−1) for two recycle solids concentration values (5000 and 7000 mg/liter). The influent substrate concentration was maintained at 1000 mg/liter COD and the hydraulic recycle ratio, α, was kept at 0.3. It was found that for bottling plant (Pepsi Cola) waste‐waters, a steady state with respect to reactor biological solids and effluent COD, at different dilution rates, could be attained, lending experimental evidence to the assumption that a steady state could be reached in developing the model and also affecting the applicability of the model in industrial organic wastewater. The reactor biological solids and effluent COD calculated from the model closely agreed with the observed values at dilution rates lower than 0.5 hr−1. Operation at dilution rates higher than 0.5 hr−1 will washout the biological solids from the reactor and the recycle substrate concentration will be apparent if the concentration of XR were not increased.
Transient response of Enterobacter aerogenes under a dual nutrient limitation in a chemostat
Authors: Cooney Charles L. , Wang Daniel I. C.
Published: December 2004

Utilizing a chemostat with a dual nutrient limitation of nitrogen and phosphate, we examined the transient response of the culture following a pulse of one of the limiting nutrients (ammonia). This method provided quantitative evidence that cells can be grown under dual nutrient limitation. Furthermore, the pattern of response was consistent with the hypothesis that phosphate limitation restricts nucleic acid synthesis in the cell and that nitrogen limitation restricts protein synthesis. The net result is that under a phosphate limitation there is a restricted biosynthetic capacity which we feel is closely associated with the RNA content of the cell.
Preparation and properties of soluble–insoluble nicotinamide coenzymes
Authors: Coughlin Robert W. , Aizawa Masuo , Charles Marvin
Published: December 2004

A soluble–insoluble form of nicotinamide adenine dinucleotide (NAD+), which can be rendered either soluble or insoluble by simply adjusting the pH, has been prepared by covalently coupling NAD to alginic acid using 1,2,7,8‐diepoxyoctane. The NAD bound to the alginic acid showed the coenzymic function in the soluble state and could be collected for further use as a precipitate by lowering the pH to below 3. Coupling soluble–insoluble coenzymes with insolubilized apoenzymes is possible in fluidized and fixed‐bed reactors.
Electrolytic regeneration of the reduced from the oxidized form of immobilized NAD
Authors: Aizawa Masuo , Coughlin Robert W. , Charles Marvin
Published: December 2004

A covalently bound adduct of nicotinamide adenine dinucleotide (NAD) with alginic acid has been found to be enzymatically active and to undergo electrochemical oxidation or reduction without significant loss of its enzymatic activity. The preparation of the adduct itself (from NAD+, alginic acid, and 1‐cyclohexyl‐3‐(2‐morpholinoethyl)‐carbodiimide metho‐p‐toluenesulfonate) is also accomplished with substantially complete retention of enzymatic activity. This adduct has been converted from the oxidized to the reduced form by controlled potential electrolysis using mercury and stainless‐steel electrodes. This electrolytically produced NADH complex could be oxidized again to the enzymatically active NAD+ complex by enzymatic reaction with the proton acceptor, 2,6‐dichlorophenol indophenol, as catalyzed by diaphorase. Using this electrolytic method with immobilized NAD, it is now possible to carry out redox reactions in which NADH is enzymatically oxidized to NAD+, with the simultaneous electrolytic regeneration of the reduced form, NADH, from the oxidized form, NAD+, produced in the enzymatic reaction.
Autoclavable low cost serum‐free cell culture media: The growth of established cell lines and production of Viruses
Authors: Keay Leonard
Published: December 2004

Five cell lines (BSC‐1, CHO, Balb/c 3T3, HeLa, and KB) have been grown in serum‐free media for several months with regular schedules of media changing and subculturing. The medium found to be successful in all cases was MEM‐α (without the ribosides and deoxyribosides) supplemented with 1% bactopeptone, although simple MEM [minimum essential medium (Eagle)] with bactopeptone (BP) gave fairly good growth in the case of BSC‐1 and 3T3 cells. The addition of insulin was necessary for CHO, 3T3, HeLa, and KB cells. Only the BSC‐1 cells grew exclusively as a monolayer in the serum‐free systems, the CHO, HeLa, and KB cells growing as stationary suspensions and the 3T3 cells growing as a combination of monolayer and suspension depending on the age of the culture and the nature of the growth surface. SV40 was produced in BSC‐1 cells grown and infected in the MEM‐α, bactopeptone medium and adenovirus‐2 was produced in spinners of HeLa and KB cells grown in MEM‐α, bactopeptone, PVP‐360, and insulin. The yield of virus and infectivity of the viruses produced were about the same as those produced in conventional serum‐containing systems.
Glucose isomerase immobolized on porous glass
Authors: Lee Y. Y. , Fratzke A. R. , Wun K. , Tsao G. T.
Published: December 2004

Partially purified glucose isomerase from a Streptomyces species was immobilized on porous glass particles and studied for various characteristics concerning its use as an industrial catalyst. The activities were investigated in relation to the reaction parameters and the enzyme deactivation was studied systematically under various reaction conditions. The half‐life of the immobilized enzyme was found to exceed 200 days at 50°C. The rate equation of the reversible glucose ⇄ fructose reaction was derived and the kinetic constants were determined. The rate equation was found to be in good agreement with experimental data for both forward and reverse reactions. The degree of diffusional effects was experimentally measured and theoretically analyzed.
Cell inactivation by ultrasound
Authors: Dakubu S.
Published: December 2004

Cell survival curves have been obtained for Escherichia coli B (E. coli B) after the sonication of suspensions of the bacteria with continuous wave ultrasound at a fixed frequency of 2 MHz between peak intensities of 8.7 and 2.25 W cm−2. It was found that under suitable conditions the survival curves were reproducible and it also was found that there was a clear relationship between the rate of inactivation and the peak acoustic intensity of the ultrasound. There appeared to be a lower threshold of peak intensity below which no inactivation was observed.
Kinetic analysis of Penicillin production by semicontinuous fermenters
Authors: Giona A. R. , Marrelli L. , Toro L. , De Santis R.
Published: December 2004

The relationships between the specific rate of nutrient consumption and biomass growth and between the specific rate of penicillin production and oxygen concentration in the broth are analyzed.

The functional dependencies which have been obtained from the experimental data of industrial fermenters are used with the mass balances to develop a model of the behavior of semicontinuous operations. The proposed model allows one to study the influence of some operational parameters.

The obtained results agree with the data of industrial processes.
The Influence of oxygen concentration and of specific rate of growth on the kinetics of Penicillin production
Authors: Giona A. R. , De Santis R. , Marrelli L. , Toro L.
Published: December 2004

The role of fundamental parameters in the conduction of penicillin semicontinuous fermentations is analyzed. Biomass concentration, penicillin production, and main nutrient consumption are particularly studied. Furthermore, the conduction of the operation is simulated with regard to conditions of constant specific rate of growth and of constant oxygen concentration in the broth. An intermediate condition is also considered.
Characterization of sand as a support for immobilized enzymes
Authors: Brotherton Jeffrey E. , Emery Alden , Rodwell Victor W.
Published: December 2004

The potential of sand as a support for immobilized enzymes was investigated by preparing alkylamine sand and devising methods to measure the total number of amine groups present and the fraction available for immobilization of enzymes. Alcohol dehydrogenase (alcohol:NAD oxidoreductase, EC 1.1.1.1) and lactate dehydrogenase (L‐lactate: NAD oxidoreductase, EC 1.1.1.27) were immobilized on alkylamine sand, and the stability of the immobilized protein and dehydrogenase activity was measured. Urease (urea amidohyrdrolase, EC 3.5.1.5) was also immobilized on sand to test the applicability of these methods to larger scale immobilizations. Results suggest that sand shows promise as a support for immobilized enzymes.
Immobilized enzymes on chitosan columns: α‐Chymotrypsin and acid phosphatase
Authors: Muzzarelli Riccardo A. A. , Barontini Gaetano , Rocchetti Roberto
Published: December 2004

α‐Chymotrypsin and acid phosphatase have been immobilized on chitosan, a polyaminosaccharide, without using any intermediate reagent; the immobilized enzymes are active and their activity is much higher than for chitin‐immobilized enzymes. The best pH conditions for operating chitosan columns have been determined and columns have been used to transform substrates in large amounts, with no decrease of activity or enzyme losses. Due to the nonconvalent interaction between chitosan and enzymes, the pure and active enzymes can be eventually recovered from the columns. The effects of metal ions, aldehydes, and salts are reported and discussed. Applications are foreseen in the food and biomedical sciences and industries.
Carbon dioxide inhibition of yeast growth in biomass production
Authors: Chen S. L. , Gutmanis Feliks
Published: December 2004

Saccharomyces cerevisiae was grown under aerobic and substrate‐limiting conditions for efficient biomass production. Under these conditions, where the sugar substrate was fed incrementally, the growth pattern of the yeast cells was found to be uniform, as indicated by a constant respiratory quotient during the entire growing period. The effect of carbon dioxide was investigated by replacing portions of the nitrogen in the air stream with carbon dioxide, while maintaining the oxygen content at the normal 20% level, so that identical oxygen transfer rate and atmospheric pressure were maintained for all experiments with different partial pressures of carbon dioxide. Inhibition of yeast growth was negligible below 20% CO2 in the aeration mixture. Slight inhibition was noted at the 40% CO2 level and significant inhibition was noted above the 50% CO2, level, corresponding to 1.6 × 10−2M of dissolved CO2 in the fermentor broth. High carbon dioxide content in the gas phase also inhibited the fermentation activity of baker's yeast.
An immobilized two‐enzyme system for the activation of the lactoperoxidase antibacterial system in milk
Authors: Björck L. , Rosén C‐G.
Published: December 2004

Lactoperoxidase catalyzes the oxidation of thiocyanate by hydrogen peroxide and an intermediary product is formed with antibacterial properties. The components of this system, with the exception of hydrogen peroxide, are present in milk. H2O2 may be introduced by means of enzymatic, generation and thus make the system complete. A two‐enzyme system consisting of β–galactosidase and glucose oxidase has been developed for this purpose. The coupled enzyme reaction is shown to work with high efficiency at the neutral pH of milk although the enzymes as such, particularly lactases suitable for immobilization, have optimal activities at much lower pH values. The results indicate that the lactoperoxidase system may in this way be employed to inactivate bacteria present in milk.
The kinetics of protein salting‐out: Precipitation of yeast enzymes by ammonium sulfate
Authors: Foster P. R. , Dunnill P. , Lilly M. D.
Published: December 2004

No Articles.