bluuebunny/crossref_metadata_2025 huggingface dataset:
Some experiments on the disintegration of yeast by high intensity ultrasound
Authors: Neppiras E. A. , Hughes D. E.
Published: May 2005

The effects of ambient pressure and ultrasonic power on the disintegration of yeast suspension have been investigated. The results obtained are, in the main, consistent with the theory that cell breakage is primarily a phenomenon dependent on producing gaseous cavitation in the medium. The importance of the experimental results and techniques applied to Commercial cell disintegrators is briefly discussed. A simple flow system is described which is easily attached to probe‐type disintegrators. The use of a crystal pickup for tuning and control purposes is described.
The “Bilthoven unit” for submerged cultivation of microorganisms
Authors: van Hemert Paul
Published: May 2005

A unit of four fermentors, which is specially designed for batch and continuous cultivation of pathogenic microorganisms in vaccine preparation, is described. Each unit consists of a panel with controls and recorders. The fermentor itself consists of a stainless steel lid, to which a spherical or cylindrical glass vessel is attached. Holding volumes are from 1 to 100 l. (3 and 7 l. being mostly used) and can be obtained by simply exchanging the vessels which have similar flanges.

Interchangeability, not only of the glass vessels, but also of the stirrers, pipes, pH electrodes, etc., together with variable control of temperature, stirrer speed, air or gas flow, and pH value gives the unit a maximum of versatility.
Effect of pressure on the α‐amylase catalyzed hydrolysis of starch
Authors: Griskey Richard G. , Richter Thomas
Published: May 2005

It was found that moderate pressures (16.0 to 43.1 atmospheres) perceptibly decreased the rate of α‐amylase catalyzed starch hydrolysis. The decreased rate was apparently due to pressure induced deactivation of the enzyme.
Steam corrosion and steam corrosion inhibition in autoclave sterilization of dental and surgical steel materials
Authors: Holmlund Lars G.
Published: May 2005

Steam corrosion and steam corrosion inhibition of dental and surgical instrument materials during autoclave sterilization have been investigated. The corrosion tests were performed on carbon steel test samples and on round dental burrs. Cyclohexylamine or decylamine were used as corrosion inhibitors, added to the “feed water,” i.e., deionized water, to a concentration of 0.1%. Before the corrosion experiment the surfaces of the test materials were standardized and calibrated by means of ultrasonic treatment. After the experiment the corrosion products were removed from the test samples or burrs using the same ultrasonic cleaning. Deionized water was used as cleaning liquid, and was then analyzed for the amount of Fe dissolved. The amount of corrosion was expressed as μg. Fe/cm.2 sample surface area or μg. Fe/burr. The results show that considerable corrosion occurs when carbon steels are exposed to steam during autoclaving, but if cyclohexylamine or decylamine is added to the steam under the otherwise unchanged experimental conditions the total corrosion was reduced by 96–99%. No cytotoxic effect on HeLa cells could be detected with surface products possibly containing traces of amine and/or amine salts—nor with corrosion products alone—when these products were removed from the test materials by means of ultrasonic cleaning.
The production, isolation, and characterization of a grisein‐like sideromycin complex
Authors: Maehr Hubert , Berger Julius
Published: May 2005

Streplomyces griscus var. X‐2455 produces an antibiotic complex which is active in vitro against a number of gram‐positive and gram‐negative bacteria and in mice against systemic infections caused by K, pneumoniae and D, pneumoniac. In view of the favorable chemotherapeutic index and the broad in vitro spectrum of crude concentrates, isolation of the pure antibiotic complex and the individual constituents was undertaken. The antibiotics referred to as Ho 5‐2667, Ro 7‐7730, and Ho 7‐7731 can be differentiated by tle, ultraviolet light absorption spectra, and in vitro antibacterial activities. They all contain iron and may be classified as sideromycins.

From antibiotic concentrates an antibacterially inactive substance was isolated and identified as N‐acetyltyramine.
The role of polyketides in secondary metabolite production by penicillia
Authors: Tanenbaum S. W. , Nakajima S. , Marx G.
Published: May 2005

The participation of polyketides in the biogenesis of natural products has long been bolstered by chemical analogies. Many isotopic tracer studies have validated the acetate‐polymalonate route, via presumptive extended poly‐β‐carbonyl intermediates, to a variety of fungal metabolites. Though implicit as antibiotic precursors, the ephemeral polyketides have not been isolated, nor perhaps with the exception of acetoacetate, can oligoketides become incorporated intact into secondary metabolites. However, a prototypical oligoketides in its stable lactone form, methyltriacetic lactone (3, 6‐dimethyl‐l‐hydroxy‐2‐pyrone), has been obtained from the tropolone‐producing mold P. Stipitatum. A convenient synthesis of this metabolite, by methylation of triacetic lactone followed by partition chromatographic separation of the resultant positional isomers, has been devised. In an experiment with 14C‐formate, it was shown that the hypothetical, enzyme‐bound polyketide precursor to methyltriacetic lactone is probably involved in stipitatie arid formation, and that the origin of the “extra” methyl or methyl‐derived carbons of both substances arises from the identical “C1” pool. Radioactive tracer experiments concerning the biogenesis of pulvilloric acid, a fairly unstable antibiotic substance produced by P. Pulvillorum, showed that its exocyclic carboxyl is formed following initial methyl transfer, whereas the ring system of the molecule is essentially acetate‐polymalonate derived. In order to test the hypothesis that methyl‐branched C14 polyketide precursors to pulvilloric acid exist and may become integrated into the fatty acid multienzyme complex, presumptive fatty acid congeners to pulvilloric acid such as. 1‐methylmyristie, 4‐methyllauric, or 2‐methyllauric acids were sought. These substances were, however, absent from the mycelial fatty acid spectrum, as well as from the fatty acid moieties of a crystalline glyceridc mixture obtained from the beer. Alternative approaches to the detection or isolation of polyketides are discussed.
The synthesis of tris(hydroxymethyl)acetic acid by fermentation of pentaerythritol
Authors: Goodhue C. T. , Schakffer J. R.
Published: May 2005

A process was devised for the synthesis of tris(hydroxymethyl)acetic acid by means of bio‐oxidation of pentaerythritol. A flavobacterium able to grow on pentaerythritol was isolated from the soil. Mutants were obtained that, were deficient, in their pentaerythritol oxidation system. These mutants could not grow on pentaerythritol, but when grown on an assimilable carbon source; they oxidized pentaerythritol to tris(hydroxymethyl)acetic acid. This conversion readily took place in a medium consisting of 20 g pentaerythritol, 10 g yeast extract, and 2 g acetic acid (neutralized) per liter. Since the mutants were unable to metabolize tris(hydroxymethyl)acetic acid, theoretical conversion yields were attainable. When pentaerythritol was added stepwise and the acid formed was neutralized continuously, 95–100% yields were obtained in concentrations of the order of 60 g/l.
Biochemical and physiological properties of an extracellular protease produced by Bacillus megateriurn
Authors: Millet J. , Acher R. , Aubert J.‐P.
Published: May 2005

A protease, excreted by a sporogeneous strain of B. megaterium, growing exponentially in a minimum glucose ammonium medium, was isolated. It is a neutral endopeptidase, stabilized by Ca++, inhibited by o‐phenanthroline, but not by di‐isopropylfluorophosphate. The specificity, studied on insulin B‐chain, glucagon, cytochrome c, and dipeptides substrates, indicated the need for a dipeptide backbone with both substituted amino and carboxyl groups. A requirement was observed for a nonpolar lateral chain in the amino acid whose amino group was involved in the peptide bond (Leu, Phe, Ala, He, Val). Rates of hydrolysis varied also with the amino acid whose carboxyl group was involved (e.g., His > Ser > Ala > Gly). In complex medium, supplemented with Yeast Extract, the biosynthesis of the protease was repressed during growth, but the same enzyme was excreted during sporulation. The repression was apparently of the same nature as that controlling sporulation during and after growth (e.g., repression by a mixture of amino acids or high concentration of glucose). An asporogeneous mutant showed a normal product ion of protease under all conditions, and a low intracellular protease turnover after growth. A mutant unable to produce protease showed a normal sporulation and a high protein turnover. This protease, here termed megapeptidase, seems to be a typical growth enzyme, not related to either the sporulation process or to the protein turnover after growth.
Kinetics of the liquid‐phase oxidation of acid ferrous sulfate by the bacterium Thiobacillus ferrooxidens
Authors: Lacey D. T. , Lawson F.
Published: May 2005

The kinetics of the batch‐wise liquid‐phase oxidation of ferrous sulfate by the organism Thiobacillus ferrooxidans has been studied over a range of temperatures from 20°C to 31°C and in the presence of an abundant supply of oxygen, carbon dioxide, and other nutrients.

The rate of oxidation was found to be accurately described by the equation

where t = time hr, S = concentration of ferrous ions g Fe++/1., μm = maximum specific growth rate of bacteria, hr−1. Y = mass of bacteria produced per gram of iron oxidized g/g, K = saturation constant, g Fe++/l., and X = concentration of bacteria g/1.

The value for the maximum specific growth rate, μm, was found to vary from 0.12 hr−1 at 20°C to 0.20 hr−1 at 31°C, while the value for the saturation constant K varied randomly between 1 and 2 g/1.

A method has also been described which permitted evaluation of the relevant rate constants μm and K without direct knowledge of the bacterial population. This method was found to yield values of μm and K which agreed with values determined accurately by a statistical regression analysis of the experimental data.
Engineering factors in single‐cell protein production. II. Spray drying and cell viability
Authors: Labuza Theodore P. , Le Roux J. P. , Fan T. S. , Tannenbaum S. R.
Published: May 2005

One important economical method for producing singlecell protein is to spray dry the cultured cells. This study presents some preliminary data on the effects of spray drying on cell viability. Under conditions similar to those for the production of spray‐dried milk, 4–5 log cycles destruction occurred. The results indicate that, the activation energy for thermal destruction of yeast was reduced from the normal heat treatment value of 84 kcal/°K mole to about 38 kcal/°K mole.
A dynamic mathematical model of the chemostat
Authors: Young T. B. , Bruley D. F. , Bungay H. R.
Published: May 2005

A number of experimental studies on the dynamic, behavior of the chemostat have shown that the specific growth rate does not, instantaneously adjust to changes in the concentration of limiting substrate in the chemostat following disturbances in the steady state input limiting substrate concentration or in the steady state dilution rate. Instead of an instantaneous response, as would be predicted by the Monod equation, experimental studies have shown that the specific growth rate experiences a dynamic lag in responding to the changes in the concentration of limiting substrate in the culture vessel. The observed dynamic lag has been recognized by researchers in such terms as an inertial phenomenon and as a hysteresis effect, but as yet a systems engineering approach has not been applied to the observed data. The present paper criticizes the use of the Monod equation as a dynamic relationship and offers as an alternative a dynamic equation relating specific growth rate to the limiting substrate concentration in the chemostat. Following the development of equations, experimental methods of evaluating parameters are discussed. Dynamic responses of analog simulations (incorporating the newly derived equations) are compared with the dynamic responses predicted by the Monod equation and with the dynamic responses of experimental chemostats.
Determination of oxygen‐transfer coefficients in viscous streptomycete fermentations
Authors: Tuffile Constance M. , Pinho Fred
Published: May 2005

Two types of steam‐sterilizable dissolved‐oxygen probs were evaluated for use in fermentations. A galvanic‐cell probe was selected over a polarographic probe because of its demonstrated ruggedness and dependability. Various methods for determining kLa in fermentors were compared and the oxygen balance method selected for use in viscous streptomycete fermentations. Rheological data are presented to identify a range of mash viscosity where many kLa measurement methods are not applicable. Oxygen transfer data are presented for streptomycete fermentations pilot fermentors.
Effect of incomplete mixing on the analysis of the static behaviour of continuous cultures
Authors: Sinclair C. G. , Brown D. E.
Published: May 2005

A simple model is proposed for continuous stirred microbial culture system to explain observed deviations from the behavior predicted on the basis that the fluid is completely mixed, which arises from the use of radial flow impellers in such apparatus.
Enzyme inactivation with shearing
Authors: Charm S. E. , Wong B. L.
Published: May 2005

Enzymes subjected to shearing in a viscometer are partially inactivated. It is possible with viscometry to calculate the degree of inactivation that occura when an enzyme solution flows through a capillary tube. When shear rate × exposure time is less than 104, there is little or no inactivation.

The masa average shear‐rate × time or shear, for laminar flow in a cylindrical tube is simply 16L/3D. It is surprising that for a single pass through a tube, the masa average shear is independent of flow rate and shear rate.
Electrophoresis of colloidal biological particles
Authors: Lemp John F. , Asbury Eugene D. , Ridenour Edward O.
Published: May 2005

Microscope electrophoresis was used to measure the electrophoretic mobility of polystyrene latex particles and bacterial, and mammalian tissue cells. The submicroscopic hydrophilic colloids (gelatin, serum albumin, and staphylococcal enterotoxin B) were adsorbed on latex carrier particles to determine their electrophoretic mobility and the effect of concentration, pH, electrolyte addition, and buffer ionic strength. Mobility curves as a function of pH were established for latex particles at 1 ppm concentration indicating an isoelectric point (IEP) at pH 3.6. The IEP for Escherichia coli B cells was measured at pH 2.8, Serratia marcescens at pH 2.6, Bacillus subtilis var. niger at pH 2.9, and L strain mouse fibroblast cells at pH 4.4. Using an adsorption technique, isoelectric points were measured for proteins: gelatin (acid form) at pH 9.4, serum albumin at pH 4.9, and staphylococcal enterotoxin B at pH 6.3.

Procefures for examining electrophoretic characteristics of microscopic and submicroscopic biological particles are described in order to standardize procedures and to generate results applicable to an understanding of parameters influencing concentration and purification of colloidal biological particles.
Comparison of ultrafiltration systems for concentration of biologicals
Authors: Charm S. E. , Lai C. J.
Published: May 2005

Ultrafiltration has been used with increasing frequency in recent years in biological laboratories for concentration, separation or purification of biological material. No data have been available on the comparison of the characteristics of Ultrafiltration systems currently in use. This study compares the filtration characteristics of four systems using commercially available membranes on suspensions and solutions: suspension of protein micelles (casein), cell debris (E. coli) and catalase solution. None of the four systems considered is found to be generally superior for all the suspensions and solutions. Vibration systems were most effective when relatively large particles were involved, while laminar flow recycling systems with high wall shear rates were best for dilute suspensions and proteins in solution. It was found that shearing inactivates enzymes in both recycle and vibration systems. It was also observed that vibration actually reduces flux in dilute solutions.
Preparation of L(+) β‐hydroxyisobutyric acid by bacterial oxidation of isobutyric acid
Authors: Goodhue Charles T. , Schaeffer James R.
Published: May 2005

A process for the bacterial oxidation of isobutyric acid to L(+) β‐hydroxyisobutyric acid has been developed. The strain of Pseudomonas putida (ATCC 21244) used in this fermentation was isolated from local soil. The process was carried out in a 15‐liter fermentor over a period of 70 hr and produced L(+) β‐hydroxyisobutyric acid in conversions as high as 48%. Hydroxylation of the methyl group of isobutyric acid has special interest because it is difficult to perform chemically. The useful chemical syntheses of β‐hydroxyisobutyric acid available at present do not start with isobutyric acid and are not stereospecific.
Continuous conversion of starch to glucose with immobilized glucoamylase
Authors: Smiley K. L.
Published: May 2005

Partially purified glucoamylase from Aspergillus awamori NRRL 3112 was immobilized on diethylaminoethyl cellulose in the presence of low ionic‐strength acetate buffers at pH 4.2. The active enzyme–cellulose complex was used to convert starch substrates continuously to glucose in stirred reactors. Substrate concentrations as high as 30% could be quantitatively converted to glucose at a rate of more than 25 mg/min/liter at 55°C for periods of 3 to 4 weeks in a 4‐liter reactor. Shutdowns were due to mechanical problems and not to loss of enzymes, which could be recovered with no appreciable loss of specific activity. Transfer products, such as isomaltose and panose, were present in immobilized enzyme‐produced syrups but to no greater degree than in soluble glucoamylase digests of starch.
A comparative study of immobilized amyloglucosidase in a packed bed reactor and a continuous feed stirred tank reactor
Authors: O'Neill S. P. , Dunnill P. , Lilly M. D.
Published: May 2005

The catalytic activity of amyloglucosidase covalently attached to DEAE‐cellulose was studied in a packed bed reactor and a continuous feed stirred tank reactor (CSTR) for the reaction maltose → glucose. At low flow rates mass‐transfer limitations in the bed reactor lead to lower conversions for this reactor compared to the CSTR. Simple theoretical expressions for these reactors were compared with the experimental results. There are significant differences between the kinetic parameters and pH profile of the immobilized and free enzyme. The immobilized enzyme also showed greater stability at 50°C than did free amyloglucosidase. The temperature dependence of the reaction rate was the same for immobilized and free enzyme.
Biogenesis of the L‐N, β‐dimethylleucine residue of etamycin
Authors: Walker John E. , Perlman D.
Published: May 2005

Radioactive labeling experiments have shown that radioactivity from L‐leucine‐U‐14C is incorporated into the L‐N, β‐dimethylleucine residue of the antibiotic etamycin, and that the N‐methyl and β‐methyl groups of this latter amino acid appear to be derived from L‐methionine.
Xanthan biopolymer production at increase concentration by pH control
Authors: Moraine R. A. , Rogovin P.
Published: May 2005

Efficient production of xanthan gum by fermentation with Xanthomonas campestris NRRL B‐1459 can be accomplished at concentrations of xanthan in the fermented broth > 3%. This level of more than twice that previously attained by us results from continuously controlling the fermentation pH with alkali. Only a slight decrease in fermentation rate and yield occurs. When ammonia is used for pH control, cell production more than doubles and fermentation time is shortened. However, xanthan yield is decreased by the diversion of additional sugar to growth.
Apparatus for continuous, large‐volume suspended cell cultivation
Authors: Fontanges R. , Deschaux P. , Beaudry Y.
Published: May 2005

A 30‐liter apparatus for growing cells continuously is described. Samples are taken automatically, thus obviating one of the main causes of contamination. In order to eliminate the continuous introduction of a gas stream, the pH was kept constant by means of the injection of NH4OH or NaOH. Under these circumstances, and by means of the two methods of agitation described—rotary and “by Vibromixer”—a quantity of cells of approximately 4 × 1010 is harvested every 48 to 72 hr.
Sequential 11α‐hydroxylation and 1‐dehydrogenation of 16α‐hydroxycortexolone
Authors: Lee B. K. , Brown W. E. , Ryu D. Y. , Thoma R. W.
Published: May 2005

Two‐step microbial transformation of 16α‐hydroxycortexolone to its 1‐dehydro‐11α‐hydroxy derivative, without isolating an intermediate, was achieved with an overall yield of 72% of product at a steroid substrate concentration of 3 mg/ml. The process included formation of the cycloborate complex of the substrate, hydroxylation of the borate complex with a suspension of Aspergillus ochraceus mycelium in phosphate buffer, and dehydrogenation of the 11α‐hydroxylated intermediate with acetone‐dried Arthrobacter simplex cells. The desired product was then obtained by breaking the resultant borate complex through acidification.
Effect of mineral nutrients and organic substances on the development of Thiobacillus ferrooxidans
Authors: Tuovinen O. H. , Niemela S. I. , Gyllenberg H. G.
Published: May 2005

The effect of inorganic nutrients on iron oxidation by Thiobacillus ferrooxidans was studied using a concentration of 2.0 g Fe2+/liter. Besides ammonium‐nitrogen and phosphorus, the essential nutrients were sulphate and magnesium, with the lowest unlimiting concentration being 2.0 g SO/liter and 2.0 mg Mg2+/liter for a suspension of about 108 cells/ml. Omitting nitrate, calcium, potassium, and chloride had no influence on the iron oxidation. Nitrate and chloride were inhibitory in high concentrations although the bacteria were able to adapt to their presence. Several organic compounds tested in 0.5% (w/v) concentrations inhibited iron oxidation. Complete inhibition up to 14 days was caused by fructose, lactose, meat extract, yeast, extract, peptone, and tryptone. T. ferrooxidans‐strains were able to adapt to the presence of organic material even though they were not necessarily able to use the organic compounds for energy. Some general conclusions are made concerning the role of nutrients in leaching processes.
Production of gramicidin S in batch and continuous culture
Authors: Blanch H. W. , Rogers P. L.
Published: May 2005

A mathematical model for the production of gramicidin S in batch and continuous culture is proposed. It is based on the division of the age of a cell into two phases—an immature and a mature one. A nongrowth associated product, such as an antibiotic, is assumed to be produced when the organism is in the older of these two phases, the mature state. The parameters describing the model were evaluated from batch and single stage transient continuous culture of Bacillus brevis, which produces the antibiotic gramicidin S. The predictive value of the model was studied in steady‐state single stage continuous culture and in a transient two stage system. Good agreement between the theoretical curves and the experimental results was found in the transient response of both the first and second stage systems, although at high dilution rates (0.34 hr−1) in the first stage, deviations from the predicted response were observed in the second stage. These may have been due to chemostat instability at dilution rates close to washout, lags in cell growth, and a metabolic lag on going from stage one to stage two.
The cyclone column culture vessel for batch and continuous, synchronous or asynchronous, culture of microorganisms
Authors: Dawson P. S. S. , Anderson M. , York A. E.
Published: May 2005

A simple inexpensive apparatus with a working volume of 10 liters of culture is described. Details of construction and procedures for operation of the cyclone column vessel are given. The vessel is self‐contained, so that experimental parameters of temperature and aeration are individually controlled; homogeneous mixing and representative sampling of the culture, besides control of foam without need for antifoam, are obtained. The vessel may be used in single or multistage systems for aerobic or anaerobic cultivation of organisms in batch, chemostat, or phased cultures.
Backmixing and mass transfer in the design of immobilized‐enzyme reactors
Authors: Kobayashi Takeshi , Moo‐Young M.
Published: May 2005

The effects of dispersion and mass transfer resistance on the degree of conversion in an immobilized‐enzyme reactor have been considered theoretically. It is assumed that the immobilized enzymes obey a Michaelis–Menten relationship and backmixing can be characterized by a dispersion model. For two extreme cases (perfect mixing and piston flow), approximate equations are obtained, which can be readily used to evaluate the effect of mass transfer on degree of conversion. Numerical solutions are obtained for other intermediate cases. Design charts are given which set practical limits of enzyme reactor design.
Some consideration on plasmid number in a proliferating cell
Authors: Koizumi Jun‐ichi , Aiba Shuichi
Published: May 2005

Plasmid as an extrachromosomal genetic element is an important vehicle to support the recombinant DNA technology. A picture on plasmid number per cell as a basis of expecting the gene dosage effect is worthy of drawing from the application to practice. The purpose of this communication is to present an overall and stochastic picture on the dynamics of plasmid number per cell in relation to the specific growth rate of the host cell.
Properties and quality characteristics of crystalline insulin extracted by ultrasound
Authors: Zayas Joseph F.
Published: May 2005

Crystalline insulin was obtained from the pancreas by the method of ultrasound extraction. Extreme changes of pancreas structure were noticed, including rupture of the cells of pancreatic islands and decomposition of pancreatic tissue with the formation of micro‐and macro‐canals. These changes facilitate the migration of solvent inside the structure and washing out β cell content. Structural changes were maximal in the peripheral parts of the pancreas and in frozen pancreas treated by ultrasound. A rapid filming method recorded factors influencing the extraction process—the dispersing effect of ultrasound, the rapid destruction of pancreatic particles, and the swelling and intensive pulsation of small particles in the ultrasound field. Experimental, control, and standard insulin preparations were nearly identical in Physicochemical properties and ether quality characteristics: activity determined by a biological method and electrophoresis; homogeneity and purity determined by circle chromatography; fractions of insulin determined by starch gel electrophoresis; amino acid composition; solubility; and content of moisture, zinc, and nitrogen.
Evaluation of startup and operation of four anaerobic processes treating a synthetic meat waste
Authors: Stephenson Tom , Lester John N.
Published: May 2005

Two continuous stirred tanks reactors (CSTR) and four anaerobic fluidized bed reactors (AFBR) were used to study the treatment of a synthetic meat waste during single‐and two‐stage anaerobic treatment. Four configurations were investigated; a single‐stage CSTR and AFBR and the two‐stage systems CSTR–AFBR and AFBR–AFBR. Startup of the anaerobic reactors was achieved within 50 days by use of a regime that included stepped increases in influent COD, methanol substitution of the substrate, and addition of essential trace metals such as cobalt and nickel. Two‐stage reactors removed up to 85% of influent COD concentrations of 5000 mg/L, whereas the single‐stage AFBR and CSTR removed 76 and 9%, respectively. The proportion of methane in the effluent gases increased as the influent COD concentration was increased. Volumetric production of methane was greatest for the first stage of the AFBR–AFBR system. Solids retention times calculated for the AFBRs ranged from 7 to 12 days, sufficient to support methanogenesis. The AFBRs and two‐stage systems were more resistant to an influent pH shock from the operating value of pH 6.8 down to pH 3 than the CSTRs and single‐stage reactors. It was concluded that high‐rate anaerobic treatment systems were applicable to meat industry wastewaters and that two‐stage digestion produced a better quality effluent.
Enzymatic analyses in organic solvents
Authors: Kazandjian Rafi Z. , Dordick Jonathan S. , Klibanov Alexander M.
Published: May 2005

Horseradish peroxidase has been found to vigorously act as a catalyst in a number of water‐immiscible organic solvents. The rates of peroxidase‐catalyzed oxidation of p–anisidine with H2O2 in toluene, benzene, ethyl and butyl acetates, and ether are in the range of 10–25% of that in water (pH 7.0) at the same reactant concentrations. Per oxidase was coupled with cholesterol oxidase (which was also found to be catalytically active in organic media), and the bienzymic system was successfully used for accurate, reliable, and reproducible determination of cholesterol in toluene.
Membrane separation of protein precipitates: Studies with cross flow in hollow fibers
Authors: Devereux N. , Hoare M.
Published: May 2005

Hollow fiber ultrafiltration and microfiltration membranes are examined for the processing of isoelectric soya protein precipitate suspensions. A model based on the various resistances to permeate flux is used to describe membrane performance. The main resistance to permeate flux is due to the interaction between the active membrane and the soluble and precipitated protein; that is, as compared with resistances due to the active membrane itself or the membrane support structure, or arising from concentrated soluble or precipitated protein layers over the membrane surface. Soluble protein rejection and precipitate mean particle diameter are correlated with observed values of this main resistance.

In contract to the ultrafiltration of soluble proteins, the flux rates observed when processing protein precipitate suspensions under a similar range of operating conditions do not approach a limiting value with increased transmembrane pressure. At high protein concentrations, greater flux rates may be achieved for precipitated as compared with soluble proteins. The use of a microfiltration membrane does not give further improvement in flux rate; this may be attributed to problems of pore fouling with precipitate particles.
Immobilization of hydrogenase in nylon gel containing electron mediator and application to an artificial photosystem
Authors: Nosaka Yoshio , Kuwabara Atsushi , Kobayashi Takaomi , Miyama Hajime
Published: May 2005

Hydrogenase of Desulfovibrio vulgaris was immobilized in nylon gel containing an electron mediator. With the immobilization, the stability for storage and repeated use increased and the optimal pH was shifted to the acidic side. Photoinduced hydrogen production was observed in an artificial photosystem consisting of the hydrogenase gel, metal porphyrin, and mercaptethanol.
An integrated microprocessor‐based fermenter control system
Authors: Merrill Roy D. , Bauer Keith
Published: May 2005

An integrated microprocessor‐based fermenter controller was developed in 1980 for an operational environment at Cetus Corp. The main goals in the design and construction of the system were (1) to facilitate scale‐up; (2) to provide flexibility and high performance for optimizing fermentation processes; and (3) to be cost‐effective for 15 in‐house systems. It was also developed to work in conjunction with a laboratory minicomputer for on‐line optimization experiments. The controller controls temperature, agitation, dissolved oxygen, pH, and foam throughout each fermentation run without manual intervention. The feedback control parameters have been optimized to provide very accurate control over a wide range of setpoint conditions and under rapidly changing metabolic conditions such as induced during an Escherichia coli batch run. The controller has also been configured to monitor, display, and record each of the controlled variables; support the interactive operator console; and communicate with the laboratory computer. In over 4 years of operation, these systems have met the design goals and have proven to be very reliable. The controller is described, its operational performance presented, and a typical fermentation run delineated.
Studies on the thermal inactivation of immobilized enzymes
Authors: Ulbrich Renate , Schellenberger Alfred , Damerau Werner
Published: May 2005

The thermal inactivation of a great number of immobilized enzymes shows a biphasic kinetics, which distinctly differs from the first‐order inactivation kinetics of the corresponding soluble enzymes. As shown for α‐amylase, chymotrypsin, and trypsin covalently bound to silica, polystyrene, or polyacrylamide, the dependence of the remaining activities on the heating time can be well described by the sum of two exponential terms. To interpret this mathematical model function, the catalytic properties of immobilized enzymes (number of active sites in silica‐bound trypsin, KM and Ea values in silica‐bound α‐amylase and chymotrypsin) at different stages of inactivation and the influence of various factors (coupling conditions, addition of denaturants or stabilizers, etc.) on the thermal inactivation of silica‐bound α‐amylase were studied. Furthermore, conformational alterations in the thermal denaturation of spin‐labeled soluble and silica‐bound β‐amylase were compared by electron spin resonance (ESR) studies. The results suggest that the biphasic inactivation kinetics reflects two different pathways according to which catalytically identical enzyme molecules are predominantly inactivated.
Acetonobutylic fermentation: Improvement of performances by coupling continuous fermentation and ultrafiltration
Authors: Ferras E. , Minier M. , Goma G.
Published: May 2005

The technology of coupling ultrafiltration and fermentation has been tested with the acetonobutylic fermentation in continuous mode. The device developed was sterilizable by steam and permitted drastic cleaning of the ultrafiltration (UF) membrane without interrupting the continuous fermentation. It has been shown to be an easily operated and reliable experimental tool for studying high‐cell‐density cultures and inhibition phenomena. With total recycle of biomass, a dry weight concentration of 125 g/L was attained, which greatly enhanced the volumetric solvent productivity of acetonobutylic fermentation in averaging 4. 5 g/L h for significant periods of time (>70 h) and maintaining solvent concentration and yield at acceptable levels.
Elimination of ethanol inhibition by perstraction
Authors: Matsumura Masatoshi , Märkl Herbert
Published: May 2005

Perstraction (membrane‐aided solvent extraction) was utilized for elimination of ethanol inhibition in continuous ethanol fermentation using high sugar concentrate. Hollow fibers for an artificial kidney were used as a permeable membrane, and their capacity to extract ethanol was examined by using several organic solvents. When tri‐n‐butylphosphate was used as an extractant, a 500 g/L feed glucose medium was successfully fermented by immobilized yeast cells. During this continuous fermentation a high ehtanol productivity of 48 g/h‐L‐gel was held, and the solvent requirement per consumed glucose was 6 L‐solvent/kg‐glucose.
Production of cellulase enzymes and hydrolysis of steam‐exploded wood
Authors: Martin R. San , Blanch H. W. , Wilke C. R. , Sciamanna A. F.
Published: May 2005

Steam‐exploded aspen has been examined as a candidate feedstock for both cellulose production and enzymatic hydrolysis of wood. Batch and fed‐batch cultivation methods were evaluated and compared with previous experiments using ball‐milled, crystalline cellulose (Solka Floe). Batch cultivation of Trichoderma reesei Rut C‐30 on 9 wt% water‐washed aspen yielded enzyme productivities and activities comparable to those obtained on Solka Floe (40 FP IU/L–h; 7. 5 FP IU/mL). Fed‐batch cultivation of Rut C‐30 resulted in higher enzyme productivities and tilers than batch cultivation (50 FP IU/L–h; 15 FP IU/mL). However, the overall enzyme production performance was lower than on Solka Floe at comparable cellulose feeding rates and concentrations. This may be due to the accumulation of steam explosion by‐products and lignin in the fermentor.

The hydroiysis of water‐washed steam‐exploded aspen was performed at different enzyme loadings and wood concentrations. Glucose production, using 10 and 15wt% suspension, showed that while glucose concentration increased with wood load, the yield of glucose derived from cellulose decreased. With 10wt% suspensions, it was possible to obtain a cellous conversion to glucose above 95%. Low cellulose levels in the hydrolyzates indicated that the filter paper activity ratios (approximately 1.5), a significant result since the fungus was grown exclusively on wood. mIt also suggested that the observed yield decrease is more likely to be caused by glucose than cellobiose inhibition of the enzymes.
Bubble coalescence in air‐sparged bioreactors
Authors: Oolman Timothy O. , Blanch Harvey W.
Published: May 2005

Coalescence frequency has been measured in an air‐sparged bubble column by observing the rate with which insoluble tracer gases were mixed within the dispersed gas phase. The effects of gas‐sparge rate and salt concentration were examined. Coalescence frequencies increased with increasing gas‐sparge rates approximately in proportion to the increase in gas‐phase hold up. The coalescence frequency decreased with NaCI concentration to a minimum frequency about half the frequency observed in pure water. Bubble size distributions were also measured in the air‐sparged column. The size distribution changed significantly over the same range of NaCI concentration as variations in the coalescence frequency were observed. The gas‐sparge rate showed no effect on the bubble size.
Recent developments in hydrogen management during anaerobic biological wastewater treatment
Authors: Harper Stephen R. , Pohland Frederick G.
Published: May 2005

A comprehensive review of the microbial kinetics, energetics, and substrate specificities of anaerobic waste‐water treatment systems is presented with descriptions of three different state‐of‐the‐art reactor configurations. Each of these reactor systems is intended to enrich different populations of anaerobic acidogens and methan‐ogens as a result of design and operational strategies for control of hydrogen and volatile acids. Imposition of these strategies results in different substrate utilization patterns, conversion kinetics, and operational stabilities as are currently being demonstrated in laboratory‐scale investigations.
On‐line adaptive control of a fed‐batch fermentation of Saccharomyces cerevisiae
Authors: Williams D. , Yousefpour P. , Wellington E. M. H.
Published: May 2005

The feasibility of applying an adaptive control technique to a fermentation process is investigated. The nonlinear, time‐variant parameters of a fermentation process were estimated on‐line as a series of linearized describing matrices. The matrices were used to update a suboptimal feedback law which controlled the process in real time over the linear region. Experiments were performed on a small‐scale fully instrumented fermenter with the online, real‐time adaptive control package. Results are presented for both single‐ and multivariable control, and indicate successful control of yeast cell growth.
Continuous hybridoma growth and monoclonal antibody production in hollow fiber reactors–separators
Authors: Altshuler Gordon L. , Dziewulski David M. , Sowek Judith A. , Belfort Georges
Published: May 2005

Growth of a hybridoma culture, along with production of monoclonal antibody, was demonstrated over extended periods in polysulfone hollow fiber membrane modules. The molecular weight cutoffs of the membranes were 70,000, 50,000, and 100,000 daltons. The hybridoma cell line, designated 65/26, produced IgG (2b/κ) directed at mouse thymus cell surface antigen, TL.1. Cell growth occurred in the shell space of the reactor, using supplemented RPMI 1640 (20% fetal bovine serum) supplied from a separate reservoir vessel through the hollow fiber lumen. The reservoir contained 125 mL media, which was changed every 4 days. Concentrations of immunoglobulin were determined by an enzyme immunoassay (using protein A and alkaline phosphatase‐labeled antibody conjugate). For the 10K, 50K, and 100K hollow fiber membrane modules, the maximum IgG concentrations detected in the 2.5‐mL shell space were 47.5–80, 510, and 740 μg/mL, respectively. In the 125‐mL reservoir for the 100K hollow fiber membrane module, the IgG concentration was measured at 260 μg/mL These values compare with an IgG concentration of 1 μg/mL when grown in a standard tissue culture flask and 3.2–7.6 μg/mL when grown in 100 ml media in a spinner flask. In addition, 10K and 50K hollow fiber membrane modules were run in a mode that decreased the fetal bovine serum supplement with time. Differences between these systems suggest that it is possible to obtain high IgG accumulation rates, both during and after the exponential growth phase of the hybridoma population.
Control of nitrate concentration in fermentations of Corynebacterium glutamicum
Authors: Kole M. M. , Thompson B. G. , Gerson Donald. F. , Senechal J.
Published: May 2005

A nitrate control system has been devised for the maintenance of stable nitrate concentrations throughout fed‐batch fermentations of Corynebacterium glutamicum. The feedback control system was based on the use of a nitrate‐ion‐selective electrode to directly monitor the nitrate levels in the fermentor and an automatic controller to activate a nitrate feed pump. The electrode which was used for controlling the nitrate level was stable through‐out the fermentation period. The apparent maximum specific growth rate, biomass production, protein production, biomass yields on glucose and nitrate, and amino acid production were all optimal at approximately 50mM nitrate.
Effect of immobilization on the physical and kinetic properties of soluble and insoluble trypsin–albumin polymers
Authors: Cohenford Menashi A. , Santoro Peter F. , Urbanowski Joseph C. , Dain Joel A.
Published: May 2005

Bovine trypsin was crosslinked to human serum albumin (HSA) with glutaraldehyde to form soluble and insoluble copolymers. The physical and kinetic properties of trypsin and trypsin‐HSA polymers were compared. Trypsin was heat labile, retaining only 24% of its enzymic activity after heating for 5 min at 60°C. In contrast, under the same condition both the soluble and insoluble trypsin‐HSA polymers showed enhanced resistance to heat in‐activation, retaining 81 and 100% of their original activities, respectively. The trypsin‐HSA polymers also showed shifts in pH optima, an increase in activation energy, and a broadening of their pH stability profiles.
Morphology of yeast cell wall as affected by genetic manipulation of β(1 → 6) glycosidic linkage
Authors: Jamas Spiros , Rha ChoKyun , Sinskey Anthony J.
Published: May 2005

The morphology of yeast cells as it is affected by the glycosidic linkages of constituent glucan was studied. Four different strains of Saccharomyces cerevisiae were studied. A cell wall matrix particle representing the intact original morphology and composed entirely of β‐glucan was prepared. Using prepared cell wall glucan particles, the morphology and cell wall matrix structure were examined. Genetic modification of the cell wall structure during growth results in the alteration of the shape and hydrodnamic volume of the intact cell wall particles. The shape and hydrodynamic volume of the cell wall particles can also be modified by in vitro chemical and enzymatic treatment. The shape factor and hydrodynamic volume of the whole glucan cell wall matrix particles were evaluated quantitatively using a rheological analysis. An increased degree of β(1 → 6) cross‐linking in the cell wall matrix induces a nearly 2‐fold increase in the shape factor and a 10‐fold increase in the compression modulus of the glucan particles. The disruption of β(1 → 6) glycosidic cross‐linking causes the particles to swell by up to 18% of their original volume. This was used as a strategy to isolate a yeast mutant with a high β(1 → 6) glycosidic content in the cell wall glucan.
Design of fluidized‐bed fermentors
Authors: Andrews G. F. , Przezdziecki J.
Published: May 2005

Designing a fluidized‐bed bioreactor requires choosing the best support particle (if any). Effectiveness factors (proportional to reactor volumetric productivity) are derived for flocs, solid spherical supports, porous supports, and adsorbent supports. The derivation demonstrates a mathematical procedure for reducing the diffusion/uptake equations for many components (substrates and inhibitory products) to a single equation, and for identifying the limiting component. With solid supports there exists a film thickness that maximizes the effectiveness, and the design objective is to keep the film near this optimum throughout the bed. This involves consideration of the effect of support particle density and film growth on bed stratification. Other considerations in picking support particles are obtaining reasonable values for bed height and diameter, minimizing mass transfer resistance between liquid and biomass, and preventing surface shear from stripping off the biomass.
Effect of temperature and pH on immobilized Zymomonas mobilis for continuous production of ethanol
Authors: Bajpai Pramod K. , Margaritis Argyrios
Published: May 2005

The effects of temperature and inlet pH of the medium on the ethanol productivity and activity of the immobilized Z. mobilis cells during continuous fermentation of glucose have been studied at various temperatures and pH. On changing the temperature from one steady state level to a new one, 6–8 h were required in order to fully experience the effect of a change in temperature; whereas 8–20 h were required on changing the pH. The optimum temperature of 37°C and a broad pH range of 4.4–6.0 were observed for maximum ethanol productivity and ethanol yield.