bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of gas diffusion in mammalian cell culture systems. I. Experimental
Authors: McLimans William F. , Crouse Elizabeth J. , Tunnah Kenneth V. , Moore George E.
Published: December 2004

It has been demonstrated experimentally that the thickness of fluid overlay in conventional tissue culture systems limits the oxygen available to mammalian cells growing as a submerged monolayer. A rocker culture system is described which circumvents critical problems associated with thin film culture while permitting nearly unlimited access of oxygen to the cell monolayer. Good growth of primary hepatic cells as isolated sheets has been obtained.
Use of the glucose oxidase system to measure oxygen transfer rates
Authors: Hsieh D. P. H. , Silver R. S. , Mateles R. I.
Published: December 2004

This investigation used the glucose oxidase system to simulate oxygen transfer rate in fermentation broths. It was demonstrated that the fungal preparation contained sufficient lactonase activity so that D‐glucono‐δ‐lactone did not accumulate and that the rate of production of gluconic acid was proportional to the oxygen uptake rate. Enzyme concentrations of 1.5–2 g/1 were found adequate to determine oxygen absorption rates in shake flasks while maintaining the dissolved oxygen concentration of low levels. The apparent Michaelis constant for oxygen, Km(O2), was found to be 27% saturation with air; this value along with experimentally determined uptake rates could be used to calculate dissolved oxygen concentration in lieu of using a dissolved oxygen probe. Enzyme concentrations of 5 g/l were sufficient to give linear acid production and low dissolved oxygen concentrations in a bench‐scale fermenter with no foaming or enzyme deactivation. The method is considered more valid and easier to employ than previously utilized techniques such as sulfite oxidation. Extension of the system to evaluating aeration effectiveness and scaleup of fermentation equipment is discussed.
Kinetics of continuous cultivation
Authors: Kono Takehiko , Asai Tsunetomo
Published: December 2004

Kinetic, studies were made on continuous cultivation applying the theory of microbial cell growth that was derived previously by the authors introducing the concepts of critical concentration and coefficient of consumption activity. General equations for microbial cell concentration for continuous cultivation in continuous‐stirred tank and tubular type reactors were derived theoretically. Productivity of cell mass in continuous cultivation was analyzed kinetically and the behavior of mutant populations in continuous cultivation is briefly discussed.
Factors affecting the flocculation of bacteria by chemical additives
Authors: McGregor W. C. , Finn R. K.
Published: December 2004

Pure bacterial cultures can be flocculated by a variety of chemical flocculants. Flocculation of bacteria will assist in their recovery, especially where the cells themselves are of interest, as in microbial protein production. Studies with several genera of bacteria indicate that the mechanism of flocculation is highly complex. Such interacting variables as temperature, ionic environment, physiological age, flocculant, bacterial genus, and surface shear have been observed. Jar test experiments with washed cells indicate that many of the variables are related to the release by the cell of proteins, nucleic acids, or polysaccharides. When released, these polymers may increase the required dosage of flocculant for recovery as in the case of E. coli, or the dosage may decrease as it does for Lactobacillus.
Continuous enzymatic saccharification of cellulose with culture filtrates of trichoderma viride QM 6a.
Authors: Ghose Tarun K.
Published: December 2004

Continuous saccharification of Solka Floc (cellulose pulp) in single and four‐vessel stirred‐tank reactor systems has been possible employing enzymes obtained directly from submerged fermentation of Trichoderma viride QM 6a. Studies on the effect of modification of the solid substrate, enzyme stability, substrate concentration, and the influence of reducing sugar concentration on the rate of hydrolysis are reported. While susceptibility of substrate to digestion is not affected by heating alone, it is strikingly increased by heating plus grinding, or by grinding following heating. Batch and steady state continuous saccharification experiments have yielded more than 5% reducing sugar in the effluent with a dilution rate of 0.025 hr−1 at 50°C, at a substrate level of 10%. An average glucose concentration of 3.4% has been obtained in the effluent of a continuous saccharification using 5% substrate at the same dilution rate and temperature.
The isolation of an aliphatic amidase from Pseudomonas aeruginosa
Authors: Lilly M. D. , Clarke P. H. , Houldsworth M. , Currie J. A. , Dunnill P.
Published: December 2004

A pilot‐scale process for the isolation of an aliphatic, amidase from Pseudomonas aeruginosa has been developed. A constitutive, partially irrepressible mutant was employed to give a high initial enzyme concentration. An existing laboratory isolation procedure has been scaled up and modified particularly by substitution of polyethylene glycol for ammonium sulfate precipitation as the first stage in the conversion of the fractionation to continuous operation. Full recovery of activity was achieved with the modification. The recovery of enzyme from a subsequent chromatographic stage was 85% and the maximum overall purification was 28‐fold.
Preparation and use of insolubilized amyloglucosidase for the production of sweet glucose liquors
Authors: Wilson R. J. H. , Lilly M. D.
Published: December 2004

Amyloglucosidase (EC. 3.2.1.3), partially purified from an Aspergillus species, was chemically attached to DEAE cellulose using the bifunctional reagent 2‐amino‐4,6‐dichloro‐s‐triazine. The action of the insolubilized enzyme derivative on dilute maltose and dextrin solutions was studied in a packed bed. A second and deeper bed was used to demonstrate the possibility of a continuous process for raising the dextrose; equivalents of “glucose” liquors of high concentration formed by acid hydrolysis of maize starch.
Clutivation of yeast on gas oil
Authors: Munk V. , Dostálek M. , Volfová Olga
Published: December 2004

The results achieved by the cultivation of the yeast. Candida lipolytica on gas oil are referred. By using a distillation fraction of gas oil distilling between 180–400°C, containing 10–20% of n‐alkanes, the optimal condition for biomass production and deparaffination were estimated for various dilution rates and various amounts of gas oil in the medium. The main factor, which influences the yield coefficient by hydrocarbon fermentation is the polyauxie of the hydrocarbon substrate. The penetration of dispersed hydrocarbons into the yeast cell is demonstrated on electron micrographs and the velocity and reversibility of this process is estimated by using tritium‐traced hexadecane.
Microbial transformation of hydrocarbons. II. Growth constants and cell composition of microbial cells derived from n‐alkanes
Authors: Wagner F. , Kleemann Th. , Zahn W.
Published: December 2004

Cultivation of Norcardia sp., Mycobacterium phlei, and Candida lipolytica in inorganic salt solution containing n‐alkanes C10–C20 as solo carbon and energy source was investigated. Generation times of 0.5–7.0 hr were typical during the exponential growth phase. The final cell concentrations (dry weight) were usually 9–26 g/l with n‐alkane mixtures ranging from n‐decane through n‐eicosane. A linear dependence was found between the production of cell mass and the consumption of n‐alkanes. The rest concentration of n‐alkanes in the cell mass is in all experiments smaller than 0.5% (w/w). Cell yields were Ysub 60–142% and for Ye 50–97% based on n‐alkane utilization. In one case, with the Nocardia NBZ 23, the substrate specifity on hydrocarbons and on a n‐alkane mixture C10‐C20 was studied. The cell mass recovered from the fermentations contained 47.8–57.7% carbon, 5.6–9.95% nitrogen, 7.2–9.4% hydrogen, 35–62% crude protein, and 6–36% lipid. Cellular protein and lipid synthesized by an organism is influenced by the type of nitrogen source. The amino acid, glucosamine, muramic acid, 2,6‐diaminopimelinic acid, and fatty acid distribution in organisms grown on n‐alkanes compared with a corresponding fermentation on glucose as sole carbon source were also estimated.
Growth models of cultures with two liquid phases. I. Substrate dissolved in dispersed phase
Authors: Erickson L. E. , Humphrey A. E. , Prokop A.
Published: December 2004

Mathematical models which can be used to describe batch growth in fermentations with two liquid phases are developed for systems in which the growth limiting substrate is dissolved the dispersed liquid phase. In the models, the possibilities of growth occurring at the surface of the dispersed phase and in the continuous phase are considered. It is assumed that the composition of the dispersed phase is such that substrate utilization from it causes little of no change, in interfacial area. Three special cases are examined. In the first, it is assumed that all growth occurs at the surface of the dispersed phase. In the second and third, it is assumed that growth occurs both at the interface and in the continuous phase. The second case assumes that substrate equilibrium is continuously established between the two phases while the third assumes substrate consumption in the continuous phase is limited by rate of transport of substrate to that phase. Comparison of the first model with available experimental data shows good agreement between model and data.
A laboratory‐scale pulper for leafy plant material
Authors: Davys M. N. G. , Pirie N. W.
Published: December 2004

A machine is described that, makes, from 2 to 3 kg samples of leaf, a pulp comparable to that made by the large‐scale equipment used in leaf protein extraction. It is therefore suitable for use in agronomic experiments on leaf protein yield.
The response by microorganisms to steady state growth in controlled concentrations of oxygen and glucose. I. Candida utilis
Authors: Moss F. J. , Rickard Pamela A. D. , Beech G. A. , Bush F. E.
Published: December 2004

Dissolved oxygen and glucose concentrations have been independently maintained at various concentrations for extended periods during growth of Candida utilis in continuous culture. Simultaneous observations of cytochrome concentration, growth rate, rates of uptake of oxygen and glucose and rates of production of CO2, ethanol and acid have been made during steady states at various levels of oxygen and glucose. There is an inverse relationship between dissolved oxygen and cytochrome and between glucose cocentration and cytochrome.

Studies of the transient state following a step change from high to low dissolved oxygen show that there is a lag of about 10 hr during which there is no change in the above parameters. This is followed by rapid oscillatory changes in cytochrome content and a change to a more fermentative metabolism.
The relationship between critical oxygen level and antibiotic synthesis of capreomycin and cephalosporin C
Authors: Feren C. J. , Squires R. W.
Published: December 2004

This paper illustrates the type of conclusions which may be reached by the use of an electrode for measuring oxygen tension in fermentation broths. The critical oxygen level, based on oxygen uptake, and the minimum oxygen tension necessary for maximum antibiotic synthesis for two commercial antibiotic fermentations, capreomycin and cephalosporin C, were studied. Capreomycin yields were depressed at an oxygen tension which was slightly below the critical oxygen level. Cephalosporin C synthesis was depressed at an oxygen tension higher than the critical oxygen level.
Effects of oxygen and glucose levels on lipid composition of yeast candida utilis grown in continuous culture
Authors: Babij T. , Moss F. J. , Ralph B. J.
Published: December 2004

Total lipids were extracted from the cells of Candida utilis grown at a constant population density in continuous culture. At different steady states, the environment was controlled with respect to dissolved oxygen and glucose concentrations, pH and temperature. Gas liquid chromatography was used to follow quantitative and qualitative changes in the fatty acid composition of the cells. Increasing glucose concentration resulted in higher lipid content; high oxygen concentrations increased the level of polyunsaturated fatty acids. The most significant changes in fatty acid composition took place when both glucose and oxygen concentrations were high, and under these conditions the amount, of linolenic acid was at its highest value.
Oxygen transfer in streptomyces fermentation broths
Authors: Járai M. , Gyóry E. , Tombor J.
Published: December 2004

The oxygen transfer coefficient has been investigated in S. noursci and S. lavendulae fermentation broths obtained from fermentors of different operating volumes (61., 30001., 20,0001.). Fermentors had KLas values ranging from 1.0 to 17.0 min−1, calculated from sulphite oxidation rates. The dynamic measurement of the volumetric oxygen transfer coefficient. (KLa) has been performed in the different fermenting systems. As the fermentation progressed, especially in the first stages, KLa values have decreased in both fermentations and in each system of fermentors. In order to characterise the whole fermenting system an average KLas was calculated from the obtained KLa values. The average KLa grew with increasing KLas values and ranged from 0.03 to 3.72 min−l. Some factors possibly having an influence on the, change of KLa have been studied.

The oxygen transfer coefficients of the broths have been measured in falling films and ranged from 0.05 to 0.4 cm min−1. The flow conditions have been characterized by Reynolds numbers of broths varying between 1.0 and 60.0. The average thickness of the falling films have been measured and plotted against Reynolds number. The Re+ which is the breaking‐point of the plot increased as the fermentation proceeded. In the region of Re+ the values of the oxygen transfer coefficient increased rapidly. An approximate correlation could be established between the Re+ and the physical properties of fermentation broth.
Fluid dynamics of anaerobic fermentation
Authors: Delente Jacques , Akin Cavit , Krabbe Erik , Ladenburg Kurt
Published: December 2004

In beer fermentation, yeast cells are kept in suspension, despite their higher density, by natural agitation created by ascending CO2 bubbles. Yeast cells are unable to nucleate bubbles but instead release CO2 in a soluble form in such a way that the medium tends to become supersaturated.

A higher concentration of yeast cells and the presence of solid particles cause the formation of bubbles at the bottom of the fermenter and practically only there. The rising bubbles grow and accelerate by sweeping the CO2 formed throughout the fermenter by the suspended yeast cells, thereby creating a fluid regime. A mathematical expression relating the bubble agitation power to the fermentation parameters was obtained and used to design more efficient fermenter shapes.
The foams of fermentation broths. I. Some parameters of the foaming of fermentation media
Authors: Szarka Laszlo , Magyar Karoly
Published: December 2004

The stability of foam formed during fermentation is decisively affect ed by the nature of the nutrient media used. In froth‐flotation models, (a) the foam formation time, characteristic of the tendency to foam, and (b) foam subsistence time, characteristic of the stability of foams formed, have been studied. With the utilization of these two parameters, the stability of foam from aqueous solution of several surface active components of nutrient media has been noted as a function of concentrations. Further, but, without attempting completeness, the viscosity enhancing effect of carbohydrate components, and the effect of the subsistence time of their foam, upon the stability of foam have been studied together with the correlation between “standing” time after sterilization and tendency to foam. Taking soy‐bean meal as a model, the stability of foam films in function of pi I, at constant concentration, has been studied. It seems that though a proper control of the factors mentioned, nutrient media with a low tendency of foaming can be formulated.
Microprobe techniques for determining diffusivities and respiration rates in microbial slime systems
Authors: Bungay H. R. , Whalen W. J. , Sanders W. M.
Published: December 2004

A microprobe electrode was used to determine dissolved oxygen concentrations near the surface and within a bacterial slime mass supplied with a continuous flow of nutrient solution. With dilute medium, the oxygen profile became level at high concentrations within the film, indicating substrate‐limited respiration. More concentrated medium caused the profile to fall to low oxygen concentrations characteristic of oxygen‐limited respiration. Oxygen responses to sudden changes in concentration of nutrient medium were measured. Estimates of microbial respiration rate and of diffusivity of oxygen were based on well‐known diffusion equations.
The influence of growth conditions on the composition of some cell wall components of Aerobacter aerogenes
Authors: Tempest D. W. , Ellwood D. C.
Published: December 2004

With a chemostat culture, both the bacterial growth rate and the growth environment can be independently varied between wide limits. Changing the growth rate of Aerobacter aerogenes organisms (in either a glycerol‐limited medium or a Mg2+‐limited medium) affected the bacterial cell wall content; invariably slow growing organisms were smaller than faster growing ones and had a higher cell wall/biomass ratio. Changing the growth rate also influenced the composition of the walls but in this respect glycerol‐limited organisms and Mg2+‐limited organisms behaved differently. Thus, whereas increasing the growth rate of glycerol‐limited cultures caused the cell wall 2‐keto‐3‐deoxyoctonic acid (KDO) and heptose contents to increase progressively, with Mg2+‐limited cultures they decreased. Furthermore, although KDO and heptose are both components of the lipopolysaccharide layer, their ratio varied with growth rate, and with the nature of the growth‐limitation, indicating changes in the lipopolysaccharide composition. These results are discussed with particular reference to the influence of environment on cell wall content and composition, and the use of continuous culture for the production of bacterial vaccines.
Studies of fungal growth and intermediary carbon metabolism under steady and non‐steady state conditions
Authors: Carter B. L. A. , Bull Alan T.
Published: December 2004

The physiology of Aspergillus nidulans strain 224 has been studied under conditions of batch‐ and glucose‐limited chemostat‐culture and the effect of different steady state growth rates and dissolved oxygen tensions (DOT) examined. Measurements of the specific activities of selected glucose enzymes, the extent of oxygen uptake inhibition by glycolytic inhibitors, and radiorespirometric analyses were made in order to follow the variations in glucose catabolism, which occurred under these conditions. Greatly increased activity of the hexosemonophosphate (HMP) pathway was found during: (i) exponential growth of batch cultures; (ii) at near maximum specific growth rates (μ = 0.072 hr−1) (DOT = 156 mm Hg); and (iii) at low DOT levels (<30 mm Hg) (μ = 0.050 hr−1) in chemostat cultures. These changes in glucose eatabolism have been discussed in terms of the biosynthetic demands of the fungus under the influence of changing growth pressures. Preliminary studies also have been made of transition state behavior following stepwise alteration of the DOT. A new steady state was established after 4–5 culture doublings during which period an “overshoot” in HMP pathway activity occurred; these kinetics are indicative of a derepression of certain glucose enzymes. Low molecular weight phenols are synthesized during the exponential phase in batch cultures and these are further metabliized to a major secondary metabolite, melanin, at the onset of stationary phase conditions. The kinetics of tyrosinase production in steady state chemostats differs from those that might be predicted for an enzyme associated solely with secondary metabolism. A primary physiological role for this oxidase in Aspergillus nidulans has been postulated.
Cell growth and population activity of Saccharomyces cerevisiae in two‐stage continuous cultivation
Authors: Beran K. , Zemanová J.
Published: December 2004

Continuous culture in a cascade of vessels with the addition of supplemental nutrients to any stage permits adjustment of the physiological state of the culture in each stage to best achieve a desired performance goal. The yeast Saccharomyces cerevisiae in two‐stage continuous cultivation was selected as a model system. With conditions in the first stage held constant‐ at a selected glucose concentration in the feed stream, dilution rate for the second stage was varied. Cell numbers, dry weight, glucose concentration, respiration coefficient, and titers of several enzymes were determined. The seed rate was defined as the ratio of glucose concentration in the feeds to stage 1 and to stage 2. At low seed rates, the calculated specific growth rate in the second stage was proportional to dilution rate. At higher seed rates, the specific growth rate based on dry weight behaved differently from that based on cell numbers, and the dependence on dilution rate was not linear.
A continuous, multistage tower fermentor. I. Design and performance tests
Authors: Falch Edvard A. , Gaden Elmer L.
Published: December 2004

The design of a continuous column fermentor with a multiple staging effect is described. The column is divided into four compartments by horizontal perforated plates and is provided with a central agitator shaft driving an impeller in each compartment. A tube at the center of each plate forms a liquid seal around the shaft and also acts as a “downcomer.”

The fermentor is normally operated with counter‐current flow of gas and medium. Fresh medium is added to the top stage and product is withdrawn from the bottom.

The effect of plate and agitator design on fermentor performance was studied in terms of factor such as oxygen transfer rate, gas holdup, and interstage mixing. By proper choice of the design parameters, the fermentor was made to approximate a perfect four‐stage cascade in terms of reactor performance.

Preliminary experiments were performed with air‐water systems, but a more realistic picture of fermentor performance was obtained in experience involving propagation of Escherichia coli. Data for business and substrate concentrations in each stage confirmed the staging effect of the apparatus. The fermentor operated in a stable manner for periods of more than two weeks.
Design and physical characteristics of a multistage, continuous tower fermentor
Authors: Prokop A. , Erickson L. E. , Fernandez J. , Humphrey A. E.
Published: December 2004

A multistage tower laboratory fermentor has been constructed consisting of eight compartments separated by sieve plates. Flow of substrate and air is concurrent from the bottom to the top of the column. It, was hoped that this system could be used to reproduce, simultaneously on a continuous basis, eight distinct phases of a batch growth curve. It was believed that the extent of batch curve simulation would depend upon the character of hydraulic mean residence time of broth in the column and in the individual compartments. The expected relationship did not occur. Rather it was found that growth in the column involved residence time characteristics not only for the fluid but also for the microorganisms, and for the growth limiting substrate. Depending upon the column operation, these could be distinct and different.

The purpose of this investigation was to study the residence time distribution (RTD) of the continous (fluid) and dispersed (microorganisms) phases for model systems as well as for a yeast fermentation. Various degrees of flow nonideality, i.e., fluid blackflow and dispersed phase sedimentation, were noticed. The former seems to be due to interaction of the concurrent gas and liquid flow; it is particularly dependent upon void area of the sieve plate holes. Sedimentation is probably a function of plate design as well as cell size and density. It wa concluded that for a particular plate design the gas hold‐up wass controlled by superficial air velocity and was the main parameter governing the differences between dispersed and continous phase(Rt1). This conclusion was supported by a computeraided styudy utilizing a mathematical model of fluid flow to fit the growth kinetics and cell distribution observed experimentally throughout the fermentor.

Some advantages of foam control in the tower fermentor by surface active compounds are mentioned. Also, suggestions are made for carrying out fermentations that have two liquid phases, such as a hydrocarbon fermentation. The possibility of closely approximating plug‐flow conditions in the multistage tower fermentor, a necessary condition for batch growth simulation, is discussed from a practical point of view.
The design and operation of high‐power, magnetic drives
Authors: Cameron J. , Godfrey E. I.
Published: December 2004

A description is given of the design and operation of high‐power magnetic drives developed to enable shaft seals and glands to be dispensed within deepculture vessels, in tissue homogenizers, and in mixing and filling processes where sterility is essential. The drives operate at speeds of 300 to 2000 rpm in volumes of 300 1. to 10 ml with clearances up to 16 mm between the pole faces of the magnets.

Two types of drive are described, one in which the driving and driven magnets form an integral unit on the lid of a vessel: such vessels are used for transporting material. To intiate stirring, it is only necessary to connect a motor directly, or through a cable‐drive, to the magnetic‐drive assembly. In the other type of unit the driving magnet is attached permanently to the driving motor. Locating pins on the base of the motor and corresponding sockets on the lid of the vessel ensure that when the motor is in position, the driving and driven magnets are located correctly in relation to one another.

The design of these drives is based on the use of multipole, ceramic magnets. The advantages of their use in such units, compared with metal magnets, are discussed. Earlier magnetic drives are also discussed and explanations offered for the difficulties formerly met in scaling up.
A flow cell photometer for bacterial growth monitoring
Authors: Blachère H. , Jamart G.
Published: December 2004

A flow cell photometer is described with automatic cleaning of the photometric cell, denasimetric separation of air bubbles and precipitates, and a constant sensitivity from 0 to 10 mg/ml of bacterial dry weight.
Isolation and characterization of constituents in hemolymph from healthy and diseased japanese beetle larvae
Authors: Bennett Glenn A. , Shotwell Odette L.
Published: December 2004

Studies are reviewed on the composition of hemolymph from Japanese beetle larvae, Popillia japonica. This research was conducted to determine the chemical environment required for sporulation of the milky disease organism, Bacillus popilliae. Amino acids, proteins, organic acids, lipids, carbohydrates, and oxygen content were determined in hemolymph from healthy and diseased larvae. Oxygen content of hemolymph was measured by microelectrodes implanted in the hemocoel of living larvae. Vegetative growth of the pathogen reduces the dissolved oxygen; however, as sporulation occurs, oxygen concentration approaches normal values. Trehalose, the major hemolymph sugar, is reduced by ca. 50% during the course of milky disease. Neutral lipids, phospholipids, and hydrocarbons decrease markedly with infection. Both branched‐chain and normal alkanes occur in hemolymph. Milky disease causes an increase in concentration of pyruvic, malic, glycolic, tartaric, and glyoxylic acids. The major hemolymph protein, a lipoglycoprotein, has a mol. wt. of ca. 500,000. Reduced concentration of this protein is accompanied by the appearance of a smaller protein. Amino acids that increase significantly as a result of infection are: Glutamic acid, aspartic acid, β‐alanine, phenylalanine, threonine, lysine, and serine. Hemolymph contains few peptides of low molecular weight.
Chemical and autoflocculation of microorganisms in biological wastewater treatment
Authors: Tenney Mark W. , Verhoff Francis H.
Published: December 2004

Experimental evidence is presented which indicates that both chemical and autoflocculation of microorganisms occur by the same mechanism. Basically, long chain polymeric species attach themselves between the microbial particles and agglomerate them into flocculant particles of sufficient magnitude to subside from suspension under quiescent conditions. Properties of the polymers which are produced during autoflocculation are investigated and these polymers are shown to be capable of causing the agglutination of inorganic colloids such as alumina. It is hypothesized that these biologically generated flocculating polymers could belong to a class of compounds known as transport enzymes. The experimental data qualitatively agrees with this hypothesis.
A modified procedure for the large scale preparation of tRNA from E. coli
Authors: Bauer S. , Milner Y. , Ziv E. , Shiloach J. , De Groot N. , Lapidot Y.
Published: December 2004

A procedure for the preparation of about 50 g batches of tRNA from 25 kg E. coli W is described. The method involves phenolic extraction of the cells, batch absorption of the tRNA on DEAE‐cellulose, washing the DEAE‐cellulose and packing it into a column, elution of the tRNA from the column and precipitation of the tRNA with ethanol. The method is less time and labor consuming than the methods described in the literature and can be carried out with relatively simple equipment.
Steady state multiplicity and stability of enzymatic reaction systems
Authors: Bruns D. D. , Bailey J. E. , Luss D.
Published: December 2004

Several techniques for investigating the multiplicity and stability of open isothermal enzymatic reactors are discussed and some of the pitfalls in previous thinking pointed out. The example which is used to illustrate these methods exhibits several interesting features. Among these is the existence of a stable oscillatory state which surrounds a unique steady state which is asymptotically stable to certain finite disturbances.
Acid‐Base equilibrium in aerobic fermentations: Influence of unutilizable acids and bases on the acetic acid concentration in culture liquid
Authors: Ikeda Shigeho , Ishizaki Ayaaki , Hirose Yoshio
Published: December 2004

An investigation was made on the factors influencing the acetic acid concentration in the culture liquid of the aerobic fermentations where acetie acid was used as a carbon source. The acetic acid concentration in the culture liquid changed in proportion to the amount of unutilizable acid or base supplied. This was explained by the principle of conservation of electroneutrality.

Another factor affecting the acetic acid concentration in the culture liquid was bicarbonate ions which were formed by the dissolution and dissociation of carbon dioxide in the gas phase of the fermentor. The increment in bicarbonate ion concentration was equal to the decrement in the acetie acid concentration in the culture liquid.
Nitrogen metabolism in extended aeration processes operated with and without hydrolytic pretreatment of portions of the sludge
Authors: Yang P. Y. , Gaudy A. F.
Published: December 2004

Nitrifying characteristics were compared for an extended aeration (total cell recycle) process and one employing an engineering modification of the process utilizing a “hydrolytic assist” to aid biological autodigestion. Laboratory pilot plants were run over a period of years, and it was found that the recently recommended “hydrolytic assist” did not militate against production of a highly nitrified effluent. Under this mode of operation, the effluent was as nitrified as the effluent from the normal extended aeration process. It was also found that the modified process rapidly recovered its nitrifying capability after a period of deprivation of excess ammonia nitrogen. Throughout the period of operation, substrate removal efficiency remained high.
Interactions in a mixed bacterial population growing on methane in continuous culture
Authors: Wilkinson T. G. , Topiwala H. H. , Hamer G.
Published: December 2004

The growth of a mixed methane‐utilizing culture in a continuous flow fermenter has been studied under both methane and oxygen limitation. Small additions of methanol have been shown to inhibit the methane‐utilizing moiety in the culture and it has been shown that the Hyphomicrobium sp. in the mixed culture removes any inhibitory methanol. The interaction between the methane‐utilizing Pseudomonas sp., and the Hyphomicrobium sp. has been explained and a model of the continuous mixed culture under oxygen limitation has been formulated. Qualitative predictions of transient phenomena by the model have been verified experimentally.
A study of the rheological properties of a non‐Newtonian Fermentation broth
Authors: Leduy A. , Marsan A. A. , Coupal B.
Published: December 2004

Polysaccharide was synthesized by Aureobasidium pullulans (or Pullularia pullulans) 2552 in a sucrose medium. The field apparent viscosity of the culture medium from shake flask experiments rose to 24,500 cP and then dropped toward its initial value as the fermentation progressed. The magnitude of the maximum apparent viscosity depended on the initial pH of the fermentation broth. The inoculum age influenced the cultivation period before which the maximum viscosity was reached. Rheograms of the fermentation broths showed a change in viscosity behavior from Newtonian to pseudoplastic, and then toward Newtonian characteristics during the fermentation. The calculated non‐Newtonian index was found to be a sensitive factor for the indication of the non‐Newtonian behavior. Such behavior could not be detected from rheograms. Viscosity profiles of polysaccharide isolated from various stages of the fermentation showed a change from Newtonian to pseudoplastic behavior depending on the concentration (0–2%) of polysaccharide.
Theory of the kinetics of reactions catalyzed by enzymes attached to the interior surfaces of tubes
Authors: Koyayashi Takeshi , Laidler Keith J.
Published: December 2004

A theoretical treatment is given of the kinetics of reactions catalyzed by enzymes attached to the inner surface of a tube, through which the substrate solution passes. A utilization factor, the ratio of the actual reaction rate to that in the absence of diffusional effects, is defined. A numerical procedure is proposed and numerical and approximate solutions for the utilization factor are given for five kinetic conditions: (a) Michaelis‐Menten behavior, (b) substrate inhibition, (c) product inhibition (competitive), (d) product, inhibition (non‐competitive), and (e) product inhibition (anticompetitive). When the enzyme chemically attached to a tube obeys a Michaelis‐Menten relationship, criteria for insignificant and significant diffusional effects are proposed.
Flow kinetics of L‐asparaginase attached to nylon tubing
Authors: Bunting Peter S. , Laidler Keith J.
Published: December 2004

L‐Asparaginase has been attached by chemical means to the inner surface of nylon tubing. An experimental study has been carried out of the flow kinetics for such a system, asparagine solutions at various concentrations being passed through two lengths of tubing at various flow rates. Measurements were made of the concentration of the product ammonia at the tube exit, and of the rate of formation of ammonia, under the various conditions. Apparent Michaelis constants, Km(app), were some three orders of magnitude higher than the Km for the enzyme in free solution (∼13 × 10−6JM). The results were analyzed with respect to the theoretical treatment described in the preceding paper (Kobayashi and Laidler), three different methods being employed. It is concluded that at lower substrate concentrations and flow rates the reactions are largely diffusion‐controlled, the enhanced Km(app) values being largely if not entirely due to the diffusion control; ionic strength studies showed electrostatic repulsion effects to be unimportant. At high concentrations and high flow rates (when the diffusion layer is of negligible thickness) the diffusional effects are minimized, and Km(app) approaches the true Km value for the immobilized enzyme.
An immobilized α‐galactosidase continuous flow reactor
Authors: Reynolds John H.
Published: December 2004

An α‐galactosidase which will hydrolyze the oligosaccharides melibiose, raffinose, and stachyose has been immobilized on nylon microfibrils suitable for use in large flow‐through reactors. This catalyst system is stable for many months, both under use and storage conditions. The immobilized enzyme behaves similarly to the enzyme in solution, characteristically exhibiting both product and substrate inhibition. The catalyst is prepared in situ and a large, 8‐liter reactor has been made. The catalyst has been used to reduce the raffinose concentration in beet sugar molasses.
Gel entrapment of enzymes: Kinetic studies of immobilized glucose oxidase
Authors: Hinberg I. , Kapoulas A. , Korus R. , O'Driscoll K.
Published: December 2004

Glucose oxidase (EC 1.1.3.4, from Aspergillus niger) has been entrapped in a crosslinked 2‐hydroxycthyl methaerylate gel containing 20% poly(vinyl pyrrolidone). The kinetic behavior and thermal stability of the entrapped enzyme were found to closely approximate that of the free enzyme. The entrapped glucose oxidase shows a broadened pH profile which is attributed to a buffering effect of the gel. Stability of gel entrapped glucose oxidase is extremely good at room temperature, suggesting a variety ofanalytical and control uses for this system.
Growth of microorganisms on chemically synthesized carbohydrate (“formose”) syrups
Authors: Bok Song Hae , Demain Arnold L.
Published: December 2004

Formose syrup was studied as a carbon source for growth of a series of microorganisms obtained from various collections. Approximately 80 strains of bacteria, yeasts, and molds were inoculated into a medium containing formose syrup and mineral salts supplemented with small amounts of yeast extract and casein hydrolysate to supply accessory growth factors. Two preparations of formose syrup, produced by two different laboratories, were employed. Formose syrup I, characterized by a low sugar content, was poorly utilized; syrup II, containing a higher sugar concentration, was utilized to a greater extent. Two strains of Aerobacter acrogenes yielded 1.3 g dry cell mass from an initial charge of 10 g of formose II solids, whereas growth on 10 g of D‐glucose amounted to 3.7 g.

Klebsiella aerogenes MIT‐B44, the best microbial strain isolated from soil by an enrichment technique, produced 1.3 g cells from 10 g fromose syrup II solids in supplemented medium; in direct comparisons, it produced 10–15% more cell 0.7–0.9 g cells per 10 g formose and grew with a doubling time of 55–70 min. Under such conditions, its macromolecular composition was 52% protein, 22% RNA, and 2% DNA. Although the apparent yield of cells from formose was only 8–11%, the actual yield based on formose utilized was 30%, the same as observed with glucose.

A second strain was isolated from soil by enrichment with spent broth from K. aerogenes. This unidentified gram‐negative, short rod‐shaped bacterium grew in mixed culture with strain MIT‐B44; in unsupplemented media they produced 1.55 g cells from 10 g formose II solids and 2.9 g cells from 10 g glucose.
Wall growth in mixed bacterial cultures growing on methane
Authors: Wilkinson T. G. , Hamer G.
Published: December 2004

The effects of wall growth are described for a mixed methane‐utilizing bacterial population growing in both batch and continuous culture. These effects are similar to those predicted previously by a theoretical analysis (Topiwala and Hamer, 1971).
The preparation of immobilized lactase and its use in the enzymatic hydrolysis of acid whey
Authors: Weetall Howard H. , Havewala Noshir B. , Pitcher Wayne H. , Detar Clarence C. , Vann William P. , Yaverbaum Sidney
Published: December 2004

The enzyme β‐galactosidase (lactose) obtained from several microbial sources was immobilized on zirconia‐coated porous glass particles. The immobilized enzymes were characterized by determining pH profiles, kinetic constants, thermal profiles, and operationalhalf‐lives in lactose and whey ultrafiltrate solutions. Studies were carried out on continuous reactor performance, and enzyme requirements for scale‐up were estimated. Lactose or whey hydrolyzed by this technique could find use commercially as a sweetener in a number of dairy products.
Mechanism of cell disintegration in a high pressure homogenizer
Authors: G. Brookman James S.
Published: December 2004

The disintegration of baker's yeast (Saccharomyces cerevisiae) by a high pressure homogenizer, to a pressure of 25,000 psi. (172.37 MNm−2) is described, together with details of the methods of measurement used to obtain information on the valve movement and pressure transients. The theory of the mechanism of cell disintegration is discussed.
Hydrolysis of lactose in acid whey using β‐galactosidase immobilized on porous glass particles: Preparation and characterization of a reusable catalyst for the production of low‐lactose dairy products
Authors: Wierzbicki L. E. , Edwards V. H. , Kosikowski F. V.
Published: December 2004

Partially purified lactoses (β‐D‐galactoside galactohydrolase, EC 3.2.1.23) from Aspergillus niger, Ladobacillus helveticus, and Saccharomyces lactis were immobilized on diazotized porous glass particles (mean pore diameter, 86.5 nm: particle size diameters, 75–125 μm). In acid whey containing 4–4.5% lactose, A. niger lactase gave the highest activity (89 μmoles lactose hydrolyzed/g glass, min) at 55°C and pH 4.5. Glass‐immobilized A. niger laclases (lactase‐BG) retained much hydrolytic activity after storage and periodic use for 165 days at 55°C. For values of X greater than 30%, hydrolysis of 0.12M lactose in acid whey by a continuous flow column packed with 2 ml of lactase‐BG particles could be correlated by X = 17.2(V/F) + 12.5 where X = lactose hydrolysis, percent of lactose originally present; V = volume of packed bed of lactase‐BG, ml; F = flow rate of acid whey, ml/min.
Response of the adenosine phosphate pool level to changes in the catabolic pattern of Saccharomyces cerevisiae
Authors: Akbar M. D. , Rickard Pamela A. D. , Moss F. J.
Published: December 2004

Changes in the catabolic pattern of Saccharomyces cerevisiae, growing in continuous culture, were effected by altering the glucose feed rate or the dissolved oxygen concentration. The cytochrome concentrations and the adenosine phosphate pool level of the yeast in a series of steady states and during three transitions were measured and compared with the glucose uptake rate (QG), the respiration rate (QO2), and the rate of ethanolic fermentation (QE).

Respiration was decreased at high glucose feed rates only if oxygen was low but cytochromes were glucose repressible at both high and low oxygen concentrations. In the main, QE and the levels of ATP, ADP, and AMP were decreased and cytochrome concentration were elevated at low QG values. No consistent relationship between any of the adenosine phosphate parameters and QO2 was discernible.

Evidence is presented for the concept that the QG directly controls the adenosine phosphate pool level and that a relationship between the concentration of adenosine phosphate anhydride bonds and the adenosine phosphate level is constantly maintained.
A fiber‐optic retroreflective turbidimeter for continuously monitoring cell concentration during fermentation
Authors: Hancher C. W. , Thacker L. H. , Phares E. F.
Published: December 2004

A fiber‐optic retroreflective turbidimeter has been developed to automatically and continuously assay the cell concentration in a fermentor by measuring the turbidity of the solution as a function of the light scattered at 180° to the incident light. The output signal is nearly directly proportional to the cell concentration in a fermentor when the sample stream contains from 0 to more than 50 g of cells per liter (wet weight). The device consists of a bifurcated fiber‐optics light pipe with its distal end inserted into a flow cell through which the material to be analyzed passes. A light source on one proximal branch of the light pipe illuminates the sample stream; light that is back‐scattered from participates in the stream re‐enters the light pipe and is returned to a photodetector on the other proximal branch of the light pipe. A signal conditioning system connected to the optical head by a cable provides gain and zero adjustment.
pH control and the “shoulder” effect in parallel fermentation pathways
Authors: Tanner Robert D. , Overley John R.
Published: December 2004

In an effort, to develop comprehensive mathematical models for use in optimizing fermentation processes, product rate data taken at constant pH's for the lactic acid fermentation (Lactobacillus delbrueckii) were analyzed. It was observed that the rate of acid synthesis‐time trajectories exhibited a “shoulder” effect at pH's less than 5. That is, a nearly constant rate of synthesis for up to 10 hr in the late growth phase, out of a maximum total fermentation time of 70 hr. This effect was used as a clue from which to structure the proposed model with parallel pathways. Simulating shunting pathways does, in fact, demonstrate that, the notion of parallelism is consistent with the expression of a shoulder. It is postulated, therefore, that a differential pH effect between two parallel pathways can account for the presence of a shoulder when both routes prevail, and no shoulder when either pathway predominates.
Properties and use of invertase entrapped in fibers
Authors: Marconi W. , Gulinelli S. , Morisi F.
Published: December 2004

Invertase was entrapped in cellulose triacetate fibers and the properties of the insoluble derivative were studied. Fiber‐entrapped invertase was found very stable under operating conditions. For some insoluble preparations a half‐life value of 5,300 days was calculated; a sample of invertase fibers, continuously hydrolyzing sucrose, maintained unchanged its activity for five years. The activity displayed by invertase fibers was 15–65% of that of the free enzyme, depending on the amount of entrapped enzyme and on the porosity of the fibers. At very high substrate concentrations the activity of the entrapped invertase approximated to that of the free enzyme. The pH optimum for activity was around 4.5 for the free and entrapped invertase. The native and entrapped enzyme was unstable at temperatures higher than 35°C.

The continuous hydrolysis of sucrose using invertase fiber was studied and the potential industrial application of entrapped enzyme is discussed.
Enzyme yields from cells of brewer's yeast disrupted by treatment in a horizontal disintegrator
Authors: Marffy Ference , Kula Maria‐Regina
Published: December 2004

Maltase, phosphatase, malate dehydrogenase, glucose‐6‐phosphate dehydrogenase, and 6‐phosphogluconate dehydrogenase activities were determined in the supernatant of brewer's yeast cells from samples taken at various intervals during a 90 min treatment in a Dyno‐Mill disintegrator.

In an attempt to find optimum operating conditions, the following parameters were varied: speed of rotation of the agitator, flow rate, yeast concentration in the slurry and bead diameter, and the specific rate of extraction was determined for each such variation. Analysis of the data showed that, superimposed upon extraction, there was a progressive but slow loss of total activities. Enzyme release could be expressed as an approximately first‐order chemical reaction. The results compared well with those of Follows et al. (Biotechnol. Bioeng.), 13, 549 (1971) and showed that the Dyno‐Mill can be operated under proper conditions without significant loss of enzyme activity and with high yields.