bluuebunny/crossref_metadata_2025_split huggingface dataset:
Engineering factors in single‐cell protein production. I. Fluid properties and concentration of yeast by evaporation
Authors: Labuza Theodore P. , Santos Daniel Barrera , Roop Robert N. 
Published: May 2005

AbstractThe processing of fermentor‐grown, edible yeast involves the removal of water. This can be accomplished through concentration followed by drum or spray drying. This study presents the essential physical properties of yeast solutions necessary for calculation of production economics. In addition, our initial studies of vacuum concentration show that some of the cell leakage necessary for good drying characteristics occurs. The residence time during concentration is also sufficient, to yield 1‐2 log cycles of kill which are mandatory since the final product, should contain no viable cells.
An enzyme kinetic model for describing fermentation processes
Authors: Tanner Robert D. 
Published: May 2005

AbstractAn enzyme kinetic model has been proposed to describe fermentation processes. This type of model was chosen because it is biologically sound, can incorporate all of the important engineering control variables, and can draw upon, in its development, the extensive kinetic literature. An intial qualitative test for this model was made on the gluconic acid fermentation. A necessary check of the model was that Monod's empirical cell growth and yield equations were derived as a special case. The model also offered an explanation for the hysteresis behavior of the gluconic acid production rate as a function of gluconolactone.
Microbial cell recovery enhancement through flocculation
Authors: Gasner Larry L. , Wang Daniel I. C. 
Published: May 2005

AbstractThe removal of cellular material from fermentation broths is of importance in many fermentation processes. The present work compares the performance of recently developed polyelectrolyte flocculating additives with traditionally available additives. Objectives are to establish criteria for the choice of a flocculating additive and establish optimum conditions for the formation of stable, fast settling floe, and for quantitative separation of cellular material from the medium. Fermentation broths of actively growing Candida intermedia were used to evaluate the effectiveness of fifty commercial flocculating additives at different dosages and pH values. Certain strong anionic and strong cationic polyelectrolytes and mineral hydrocolloids were found to be most effective in their enhancement of settling rates. Some differences in behavior exist between glucose grown cells, hydrocarbon grown cells, and washed cells in buffer suspension. Flocculation of cells from fermentation broths is concluded to be highly dependent upon adsorbed material. A high charge density to interact or compete with adsorbed material and a solubility in the adsorbed material are important factors in choosing an additive for a given application. The fluid mechanics of a flocculating suspension is an important variable since low shear does not provide adequate contacting between cells for floe formation and high shear leads to floe breakup. An apparatus was constructed to grow floe under constant fluid mechanical conditions both in laminar and turbulent flow regimes. Turbulent shear was found to be very important in forming large, compact floe in cases where irreversible ionic bridging is the mechanism as for the strong anionic polyelectrolyte, polystyrene sulfonate. Adequate mixing is required to disperse the flocculating additive, but the level of turbulence is relatively unimportant in cases where reversible colloidal bridging is the mechanism as for the mineral hydrocolloid, bentonite.
Gram‐Scale purification of arginine, formylmethionione, glutamic acid and phenylalanine transfer ribonucleic acids from E. coli K‐12 MO7
Authors: Weeren H. O. , Ryon A. D. , Heatherly D. E. , Kelmers A. D. 
Published: May 2005

AbstractGram‐sized quantities of purified arginine, formylmethionine, glutamic acid, and phenylalanine‐2 tRNAs have been prepared from pools of E. coli K–12 MO7 mixed tRNAs by reversed‐phase chromatography after preliminary fractionation on DEAE‐cellulose. Purified formylmethionine tRNA and partially purified arginine tRNA and glutamie acid tRNA were obtained from large‐scale RPC–3 runs (4 × 36 in. column). The arginine tRNA was further purified by rechromatography on RPC–4 columns, and the gluatmic acid tRNA by rechromatography on an RPC–3 column. Two phenylalanine tRNAs were resolved on large‐scale (2 × 96 in. column) RPC–3 runs; only the second phenylalanine tRNA reached a satisfactory degree of activity. About 0.88 g of arginine tRNA, 70% activity; 3.32 g of formylmethionine tRNA, 97% activity; 0.80 g of glutamic acid tRNA, 83% activity and O.92 g of phenylalanine‐2 tRNA, 78% activity, were produced. The processing steps employed are reliable and reproducible and the procedure is amenable to routine production of these tRNAs.
Microbial production of D‐mannitol and D‐fructose from glycerol
Authors: Onishi Hiroshi , Suzuki Toshiyuki 
Published: May 2005

AbstractIn view of the recent development that some petrochemical products are efficiently available as substrates for the fermentation industry, glycerol manufactured from propylene by chemical synthesis would also be hoped for the purpose. This paper describes some of the factors influencing mannitol production from glycerol by Torulopsis yeasts and a microbial conversion of glycerol to D‐fructose via mannitol, in which two sequential steps of yeast and Acetobacter fermentation are involved. Torulopsis mannitofaciens CBS 5981 and Torulopsis vcrsatilis CBS 1752, exceptionally good mannitol producers, were selected for the study. High concentrations of nitrogen sources and KH2PO4 in the medium markedly decreased mannitol yield in spite of good utilization of the substrate. T. mannitofaciens produced mannitol in yield of 31% of the glycerol consumed at optimal condition. The fermentation by washed yeast cells gave much higher mannitol yield of more than 50%. A sequential fermentation process was carried out without isolation and purification of the intermediate and yielded.51.7%. D‐fructose from the glycerol.
A model for continuous enzymatic saccharification of cellulose with simultaneous removal of glucose syrup
Authors: Ghose Tarun K. , Kostick John A. 
Published: May 2005

AbstractCellulase of Trichoderma viride was concentrated in various molecular cutoff membranes, and flux rates and retention of activity were studied under ultra‐filtration conditions. Little or no Cellulase was discharged through the membranes tested. The concentrated (5–8‐fold) enzymes were used to saccharify finely ground substrate (Solka Floe) in stirred tank (STR) and membrane reactors (MR). A pressure filtration vessel provided with a membrane for simultaneous removal of low molecular weight products (glucose) from the reacting system (Cellulose‐Cellulase) is designated as a membrane reactor. Continuous digestion of dense cellulose suspension in the membrane reactor was achieved. Using PM‐30 (Amicon) membrane reasonably high mass flux values (9.7–23.3 gals/ft2—day) were obtained in separating glucose from a digest of 30% cellulose suspension. Abcor membrane (HFA 300) was equally effective and necessitated less care in handling. Nearly 14% glucose concentration has been achieved in less than 50 hrs in STR by digesting a 30% cellulose suspension. Based on experimental data a model system is proposed for the continuous steady state Saccharification of ground substrate in which there is continuous removal of concentrated glucose syrup, and a feedback of enzyme.
A method for obtaining protein concentrates from microorganisms
Authors: Hedenskog Gudmund , Mogren HÅRkan , Enebo Lennart 
Published: May 2005

AbstractIn order to isolate proteins from microalgae, yeasts and bacteria, cell disintegration in a special ball‐mill was performed. The degree of disintegration of the different microorganisms was compared. The dependence of disintegration on bead size and on the ratio between the volume of suspension and the volume of glass beads was also investigated. Nondisintegrated and disintegrated cells were extracted with sodium hydroxide and the amount of extractable nitrogen and the amount of nitrogen precipitable at pH 4.0 were determined. The dependence of yield on the sodium hydroxide concentration, extraction time, and temperature was studied. When extracting undisintegrated cells, very low yields were obtained and the nitrogen extracted was mostly nonproteinous. For disintegrated cells high yields were obtained. An optimum was found after extraction with 0.3–0.5% sodium hydroxide; at pH 11.0–11.5. The precipitate obtained represented 60–70% of the cell nitrogen. The nitrogen content of the precipitate was 12–14% of the dry weight.
Extended culture: The growth of Candida utilis at controlled acetate concentrations
Authors: Edwards V. H. , Gottschalk M. J. , Noojin A. Y. , Tuthill L. B. , Tannahill A. L. 
Published: May 2005

AbstractExtended culture, a special type of semicontinuous culture, permits prolonged maintenance of a constant or programmed environment in a growing culture by a controlled addition of one or more substrates. Differences between extended culture and continuous culture data are a measure of differences in the properties of cell populations with different cell age distributions but identical steady‐state environments. Both extended culture and continuous culture were used to study the growth kinetics of Candida utilis (ATCC 9226) under conditions of substrate inhibition at controlled concentrations of sodium acetate in a carbon‐limited mineral salts medium supplemented with 0.01 g/1 yeast extract. Acetate concentrations ranged from 1.2 g/l to 10.8 g/l (expressed as acetic acid), while yeast concentrations varied from 0.3 to 7.8 (g dry cells)/1. Rate parameters such as growth yields (Y), specific growth rates (μ), and linear growth rates (K), were calculated by computer from the data and theory presented herein. Specific growth rates as high as 0.54/hr were observed, although extended culture growth was more nearly linear than exponential in these experiments. Growth yields usually varied between 0.2 and 0.4 (g dry cells)/(g acetate), although values were as high as 0.8 for a brief period during one experiment. Growth yields at a given acetate concentration were correlated by an equation of the form 1/Y = 1/YG + m/μ. A maintenance coefficient (m) of 0.17 (g acetate)/(g dry cell‐hr) was observed at acetate concentrations of 4.5 and 10. g/1. A typical maximum growth yield (YG) of 0.51 (g dry cell)/(g acetate) was obtained at 4.5 g/1 acetate, but an unusually high YG of 1.33 was found at 10. g/1 acetate. Oxygen uptake measurements are compared with these cell yield measurements. Linear growth rates in expended culture were correlated by the equation K = 0.89–0.70 (S/S0) where K has units of (g dry cell)/(l‐hr), S is the instantaneous acetate concentration, and S0 is the initial acetate concentration. The extended culture kinetic data are shown to be substantially different from continuous culture kinetic data. Reason for these differences are discussed in light of diffrences in the cell age distributions, as well as possible differences in experimental conditions.
Effect of mixing on the washout and steady‐state performance of continuous cultures
Authors: Fan L. T. , Erickson L. E. , Shah P. S. , Tsai B. I. 
Published: May 2005

AbstractThe effects of mixing on the critical mean holding time for washout and the steady state performance of growth processes in continuous flow reactors are investigated. Macromixing, micromixing, and cell recycle arc considered. The tanks‐in‐series model composed of N completely mixed flow reactors, the dispersion model, the plug flow model, and a combined model composed of a plug flow reactor and a continuous stirred tank flow reactor connected in series arc used to represent the macro‐mixing or residence time distribution. The extreme cases of micromixing, namely, complete segregation and maximum mixedness, as well as intermediate states of micromixing are investigated to determine their effects on washout and the occurence of multiple steady states. A technique for predicting the maximum mixedness washout condition from a knowledge of the residence time distribution is presented and used to determine the washout condition for the dispersion model under maximum mixedness conditions.
Model for continuous culture which considers the viability concept
Authors: Sinclair C. G. , Topivvala H. H. 
Published: May 2005

AbstractThe effect of the rate of ‘natural death’ of bacteria on the steady state behaviour of continuous culture has been studied. A model which has no real biochemical basis but which gives good experimental correlation has been proposed. Populations of Acrobacter Acrogenes harvested from the chemostat at dilution rates greater than 0.1 HR−1 were found to be over 95% viable. The effect of the rate of death on the steady state yields becomes significant only at very low dilution rates. The experimental work of other workers has also been simulated to test the validity of the model. Theoretically it is also shown that an ‘apparent’ lag in batch cultures will be observed if the innoculum is of very low viability.
The effects of glucose and oxygen on the cytochromes and metabolic activity of yeast batch cultures. I. Saccharomyces spp.
Authors: Rickard Pamela A. D. , Moss F. J. , Ganez Micheline 
Published: May 2005

AbstractSaccharomyces cerevisiae and Saccharomyces carlsbergensis were grown in batch culture with and without oxygen control.The concentrations of A‐, B‐ and C‐type cytochromes of both yeasts were dependent on the oxygen concentration during growth as well as on the initial glucose concentration of the growth medium. S. cerevisiae cytochromes were maximal after growth in low glucose and low oxygen; S. carlsbergensis cytochromes were maximal after growth in low glucose and high oxygen. Except when glucose was in very low concentration, its catabolism by S. carlsbergensis was directed predominantly towards ethanolic fermentation regardless of the oxygen concentration. Growth rate, total cell mass and yield were maximal, and anabolism was closely balanced with catabolism, when glucose and oxygen of S. carlsbergensis cultures were both high. Under these conditions neither catabolism, respiratory or ethanolic, nor glucose uptake were maximal.
Equipment for the automatic aseptic inoculation and sampling of microbial cultures
Authors: Lelieveld H. L. M. 
Published: May 2005

AbstractEquipment has been designed and constructed for the automatic aseptic inoculation and sampling of microbial cultures. It enables fermentations to be started and samples to be taken round‐the‐clock, according to a predetermined program.The equipment is suitable for microbial processes on both a laboratory and a factory scale.
The effects of glucose and oxygen on the cytochromes and metabolic activity of yeast batch cultures. II. Candida utilis
Authors: Rickard Pamela A. D. , Moss F. J. , Phillips D. , Mok T. C. K. 
Published: May 2005

AbstractCandida utilis was grown in batch culture with and without oxygen control. The concentrations of A‐, B‐, and C‐type cytochromes were found to vary with the initial glucose concentration, with the dissolved oxygen concentration, and with time. A‐type was the most sensitive. After glucose was essentially exhausted, the yeast catabolized ethanol, if it had been growing in a relatively low initial glucose concentration, or non‐glucose carbohydrate, including some of that previously accumulated within the cell, if it had been growing in a high initial glucose concentration. This difference in metabolic pattern could explain why cytochrome derepression was initiated soon after glucose uptake ceased only if initial glucose had been relatively low. The effects of glucose and dissolved oxygen concentrations on yeast cytochromes and respiratory activity are discussed.
A mechanistic study of oxygen transfer in aqueous systems
Authors: Muchmore C. B. , Chen J. W. , BeMiller J. N. 
Published: May 2005

AbstractOxygen transfer coefficients were evaluated for a 14‐liter stirred tank fermentor equipped with an oxygen probe, employing elemental copper adsorbed on a weakly basic anion‐exchange resin as a solid phase oxygen acceptor. The use of a solid phase oxygen acceptor allowed evaluation of mass transfer resistances associated with the solid phase, and the effect of an oxygen adsorbing solid phase on the overall oxygen transport system, portions of the oxygen transfer process that are neglected by the conventional sulfite oxidation method commonly employed. It was concluded from the data obtained that a transport pathway involving transfer of oxygen to particles present near the air‐water interface was a significant oxygen transport pathway for the system studied. Oxygen probe measurements performed on the bulk liquid did not recognize this pathway, suggesting that data taken on biological systems by use of techniques involving oxygen concentration measurements in the bulk liquid may not give the true oxygen absorbing capacity of a system.
Effect of sludge flocs on the aeration performance of suction‐impellers
Authors: van der Kroon Gerard T. M. , Vlot Jaap 
Published: May 2005

AbstractThe authors have investigated a special aspect of the transfer of oxygen: the aeration performance of small‐scale suction‐impellers in a suspension of activated sludge floes and a performance comparison with clear water. The principle of the impellers is, that in order to disperse air bubbles into the aforementioned liquids, all that we need do is a simple stirring. Due to the impellers the authors could not show a reduction of the oxygen transfer coefficient in the presence of sludge flocs. Former comparative studies of oxygen transfer, using a fixed orifice, did show a reduction in the presence of sludge flocs. Therefore, it seems probable that the effect of activated sludge flocs on the transfer coefficient is linked with the manner in which air is dispersed, i.e., depends on whether an orifice is fixed or moved. The experimental results allow presumption that by developing a high intensity of shear near the location where air bubbles are produced, we are able to minimize the effect of sludge flocs on the process of bubble formation.
Improved medium for saprophytic production of ergot alkaloids by Claviceps purpurea (Fr.) Tul.
Authors: Sambamurthy K. , Rao L. Nageshwara 
Published: May 2005

AbstractStudies were undertaken on the production of ergot alkaloids in saprophytic culture employing two strains of C. purpurea. In an attempt to improve the yield of the alkaloids and to develop a cheaper medium, the commonly used carbohydrate source, mannitol, was replaced with different types of starches and starchy materials as these are comparatively much cheaper than mannitol. Results indicated that, in stationary cultures, certain starches enhanced the yield greatly, while in shaker cultures starches could replace mannitol for equivalent yields.
A generalization of kinetic data on sulphite oxidation systems
Authors: Linek V. , Tvrdík J. 
Published: May 2005

AbstractKinetic data of the reaction between sulphite ions and dissolved oxygen depend on the purity of sulphite used. Thus it is adequate to determine them for each batch and concentration of sulphite used. Besides the dependence of reaction rate constants on catalyst concentration, it is usually also required to know their dependence on pH and on temperature. Both quantities can change to a great extent especially in absorption apparatus in which high sulphite conversion occurs. They profoundly influence the value of the reaction rate constant. To get a complete picture of the influence of these three quantities without repeating extensive kinetic measurements for every kind and concentration of sulphite used, a method for obtaining information on the influence of all three quoted quantities in the range of values of interest for application is presented.
Effect of shear on the death of two strains of mammalian tissue cells
Authors: Augenstein D. C. , Sinskey A. J. , Wang D. I. C. 
Published: May 2005

AbstractThis study reports some findings on the death of mammalian cells occurring from fluid dynamic effects when they are pumped through capillaries. The cell strains used were human HeLa S3 and mouse L929, grown in monolayer culture. Cells were harvested and suspensions were pumped through various lengths and diameters of stainless steel capillary tubing. Viability of the cells was assayed by the dye exclusion test. Cell deaths occurred and could be correlated with either average wall shear or power dissipation within the capillary tube. L929 cells were found to be more sensitive than HeLa S3 cells at all shear rates tested.
Oxygen transfer and scale‐up in lysine production by Ustilago maydis mutant
Authors: Sanchez‐Marroquin A. , Ledezma M. , Barreiro J. 
Published: May 2005

AbstractThe oxygen transfer coefficient estimated by both sulfite and dynamic methods and some of the rheological properties of fermentation broths derived from the batch cultivation of a mutant of U. maydis in a sugar cane juice substrate, are used in a scaling‐up procedure on the basis of the power consumption per volume unit concept. The fluid was of the Binham plastic type; the Np‐NRE correlations showed that the modified Reynolds numbers of the flat‐blade turbine impellers were low, near to or in the laminar region; the Na‐Pg/P relations were established and then used in the calculation regardless of the geometrical dissimilarities of the vessels. A change of scale from 5 to 50 liters was calculated and operated keeping the power per volume value constant. Reproduction of lysine yields, 2.5–3.2 g/liter, was repeatedly reached in 8 successive runs.
Simulation of oxygen transfer in microbial slimes
Authors: Bungay H. R. , Harold D. M. 
Published: May 2005

AbstractA model based on diffusion mechanisms accounts for oxygen transfer from flowing nutrient medium into a film of organisms in slime. Profiles of dissolved oxygen concentration are generated at distances downstream from the start of the slime. In these studies, the nutrient medium was assumed rich, thus the rate of oxygen transport limited microbial respiration. Parameter sensitivity tests were performed for flow rate, oxygen concentration in the medium, and mass transfer coefficients.