bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancement factor for oxygen absorption into fermentation broth
Authors: Yagi Hideharu , Yoshida Fumitake
Published: December 2004

Values of the enhancement factor for oxygen absorption into fermentation broth, i.e., the ratio of the liquid phase mass transfer coefficients for oxygen absorption for both cases with and without respiration of microorganisms were predicted theoretically on the assumption of various cell concentration distributions. Calculations indicate that in the usual case the enhancement factor is only slightly or negligibly larger than unity, even when accumulation of microorganisms at or near the gas‐liquid interface is assumed. Results of experiments with sparged‐stirred fermentors on oxygen absorption into fermentation broths containing resting and growing cells of Candida tropicalis confirmed the theoretical prediction. Except for extreme cases, the effect of respiration of microorganisms on kLa, values can practically be ignored.
The effect of acid pH on the growth kinetics of Trichoderma viride
Authors: Brown D. E. , Halsted D. J.
Published: December 2004

Batch cultures of Trichoderma viride have been carried out in a 10 liter stirred fermenter at controlled pH values of 2.5, 2.7, 3.0, and 4.0, and without pH control at a temperature of 28°C. Cell and glucose concentrations and dissolved oxygen values are reported. The yield coefficient was found to be constant at 0.40 kg cells/kg glucose and the maximum specific growth rate was linearly correlated with the hydrogen ion concentration.
Dynamic and steady state studies of phenol biodegradation in pure and mixed cultures
Authors: Der Yang Ren , Humphrey Arthur E.
Published: December 2004

The microbial degradation of phenol by pure and mixed cultures of Pseudomonas putida was studied in batch, phenol‐stat, and continuous culture systems. In the continuous culture runs, both steady state and transient experiments were performed. From these experiments, a model for the kinetic behavior of the organisms was evolved and an analysis performed on the stability and dynamic behavior of pure and mixed cultures. The results indicate that it should be possible to achieve phenol removal from wastewaters down to levels of 1‐2 ppm in a single stage system. However, because of the effects of substrate inhibition on kinetic behavior of the microorganisms, long lasting transients can occur. The transient behavior of such systems cannot be solely determined from μmax or Ks, parameters, but must include a consideration of the transient size and response characteristic of the organism.
Production of plant virus inhibitor by Phytolacca americana suspension culture
Authors: Misawa Masanaru , Hayashi Mineyuki , Tanaka Hozumi , Ko Keido , Misato Tomomasa
Published: December 2004

The inhibitory activity of tobacco mosaic virus (TMV) infection was assayed with the extracts of various callus tissues derived from the intact plants. Phytolacca americana callus was selected as a producer of the virus inhibitor and its cultural conditions in suspension were examined for cell growth and the inhibitor production. A modified liquid medium containing twofold concentrations of all components in that of Murashige and Skoog plus 2,4‐D (1.0 mg/liter) and sucrose (6%), but without any vitamins and glycine was chosen for production of higher levels of the inhibitor. TMV infections in tobacco, bean, and tomato plants were markedly inhibited by the introduction of the disrupted whole broth of suspension cultured P. americana.
An evaluation of a ceramic monolith as an enzyme support material
Authors: Benoit Michel R. , Kohler Joseph T.
Published: December 2004

Catalase was immobilized on commercially available monolithic catalyst supports and also on participate support obtained by crushing the monolith. The kinetics of the monolith‐ and particulate‐supported enzymes were analyzed in a continuous tubular reactor system and pressure drop was also monitored. Analysis of the results indicates that the monolith‐supported system presents very little resistance to flow which results in a considerably smaller pressure drop than is obtained in flow through particulate‐supported systems under comparable conversion conditions. Ceramic monoliths thus appear to be very suitable for use as enzyme supports in continuous tubular reactor applications, particularly where high pressure drops might be expected.
Kinetics for activated sludge process design: Experiment application to straw paper wastewater treatment
Authors: Del Borghi Marco , Migliorini Giorgio , Isola Giacomo , Ferraiolo Giuseppe
Published: December 2004

Degradation kinetics for the treatment of straw paper wastewater in an activated sludge process have been studied and a kinetic model has been derived for both batch and continuous experiments. These two methods are reasonably equivalent only when rather low concentrations of substrate are involved. In other cases batch and continuous results are quite different. Both models, however, show a dependence upon concentration corresponding to that which is typical of multicomponent substrate degradation. The kinetic model derived from continuous tests appears to be more suitable for designing industrial processes in that it avoids oversizing of the aeration unit.
Pectinolytic activity of Saccharomyces fragilis cultured in controlled environments
Authors: Wimborne Margaret P. , Rickard Pamila A. D.
Published: December 2004

Seven of 30 yeast stock cultures, covering nine genera, and 13 of 39 yeasts isolated from grapes gave positive reactions when screened for pectinolytic activity on pectin gel plates. The seven stock cultures covered six species and four genera. Only one of the yeasts, Saccharomyces fragilis Y49, excreted discernible pectinolytic activity into the fluid of shake flask cultures; the activity was partially constitutive and was repressed by high oxygen tensions.
Experimental operation of immobilized multienzyme systems in optimal and suboptimal configurations
Authors: Chang Ho Nam , Reilly Peter J.
Published: December 2004

Two mixed immobilized enzyme systems, glucoamylase–glucose isomerase and glucose isomerase–glucose oxidase–catalase, were operated to verify theoretical predictions that optimal bifunctional catalyst configutations could exist superior to those where the catalysts were mixed uniformly or arranged sequentially in a tubular reactor. The experimental results for all three configurations conformed to the theoretical values sufficiently closely to support of optimal catalyst profiles.
Mathematical modeling of lag phases in microbial growth
Authors: Pamment N. B. , Hall R. J. , Barford J. P.
Published: December 2004

This paper describes a mathematical model of the lag phases of Saccharomyces cerevisiae that incorporates the basic concepts previously presented in a two‐stage deterministic model for the growth of this organism under conditions of oxygen excess with a sugar as the growth‐limiting substrate. The model structure was suggested by an extensive investigation of the causes of the lag phases of S. cerevisiae which found that, in contrast to the traditionally accepted trends, the length of the lag phase was not inoculum‐size dependent. This was consistent with other previously published work which suggested that a major factor in the length of the lag phases in S. cerevisiae was the need to synthesize adequate levels of glycolytic and respiratory enzymes. These suggestions were confirmed experimentally with lag‐age data. Based on this conclusion a mathematical model was developed incorporating a description of the levels of glycolytic and respiratory enzymes and their effect on the growth rate and metabolism. This model was tested experimentally and the initial results indicate indicate that many aspects of the lag phase of this organism may be described mathematically. The experimental findings further support the concept of primary regulatory control proposed by Bijkerk and Hall.
Role of formaldehyde in the utilization of C1 compounds via the ribulose monophosphate cycle
Authors: Papoutsakis Eleftherios , Lim Henry C. , Tsao George T.
Published: December 2004

Formaldehyde, an intermediate in methanol oxidation, plays an important role in controlling methanol utilization by microorganisms which fix carbon via the ribulose monophosphate (RMP) cycle. The extracellular formaldehyde concentration profiles in batch cultures at low and high starting methanol concentrations with and without the presence of semicarbazide in the media, suggest the role played by formaldehyde. The impact of formaldehyde on growth is demonstrated by the time dependent and the initial methanol concentration‐dependent cell‐mass‐yield coefficient. Kinetic studies of the enzymes involved in the oxidation and incorporation of C1 units suggest that enzyme inhibition cannot account for the observed growth inhibition. A mechanism is proposed to explain methanol and formaldehyde utilization that stresses the transcriptional regulation of mass flow around formaldehyde in assimilation and oxidation pathways through repression and induction.
Immobilized α‐chymotrypsin: Pore diffusion control owing to pH gradients in the catalyst particles
Authors: Halwachs W. , Wandrey C. , Schügerl K.
Published: December 2004

The fast enzymatic hydrolysis of D,L‐phenylalanine methylester (DLE) to L‐phenylalanine (LA) and D‐phenylalanine methylester (DE) with immobilized α‐chymotrypsin was chosen as a model reaction. Under the experimental conditions applied in the present investigations the pore diffusion is the rate‐limiting step of this reaction owing to the pH gradient in the particles. The effectiveness of the catalyst is experimentally determined as a function of the substrate concentration based on measurements of the enzyme protein content of native and immobilized enzyme. The proteolytic reaction is theoretically treated by also using a pore diffusion model which takes into account the concentration gradients of substrate and product, pH‐ and enzyme activity profiles, as well as the change of buffer capacity of the solute in the catalyst particles. The model parameters were experimentally determined for the investigated system. It can be shown that conditions are possible for which the effectiveness of the catalyst exceeds unity.
Kinetics of enzymatic hydrolysis of cellulose: Analytical description of a mechanistic model
Authors: Okazaki M. , Moo‐Young M.
Published: December 2004

A generalized mechanistic model for the enzymatic hydrolysis of cellulose is developed and expressed mathematically. The model is based on Michaelis–Menten‐type kinetics for concurrent random and endwise attack of the substrate involving end‐product inhibitions and three types of enzymes: an endo‐β;‐1,4‐glucanase, an exo‐β‐1,4‐glucanase, and β‐glucosidase. Basic parameters of the model which can explain synergistic and other effects observed experimentally are quantified and discussed. It is shown that cellulose degradation kinetics are expected to be strongly affected by the ratio of endo‐ to exocellulases in the reaction mixture as indicated by previous experimental data, and the substrate degree of polymerization, a factor not fully appreciated in previous studies, which appear to be overridingly important in many practical cases.
Continuous determination of ethanol during aerobic cultivation of yeasts
Authors: Bach H. P. , Woehrer W. , Roehr M.
Published: December 2004

A new sensor for the continuous determination of ethanol during the production of yeasts, growing aerobically on fermentable sugars, is described. The operating principle is based on the detection of ethanol vapor in the exit air. A description of the sensor with a diagram of the measuring electronics is supplied. It was designed for the determination of ethanol contents up to 3 g/liter in aqueous solutions at 30°C. The sensitivity is very high — 1 ppm ethanol being detectable under these conditions. The aeration rate dose not affect the output signal in a wide range (0.5–2 v/v/m). Besides the unspecific sensitivity of the sensor to other easily oxidizable substances, the influence of the pO2 in the exit air, however, must be taken into account. The application of the sensor is shown in a fed‐batch culture of bakers' yeast where aerobic fermentation is caused by increasing the glucose feed rate.
Deactivation studies of immobilized glucose oxidase
Authors: Krishnaswamy S. , Kittrell J. R.
Published: December 2004

Studies have been performed in a tubular flow reactor to characterize the deactivation of immobilized glucose oxidase. The effects of oxygen concentration in the range of 0.09 to 0.467mM and hydrogen peroxide concentrations in the range of 0.1 to 10mM were studied. A simple mathematical model assuming first‐order reaction and deactivation was found to describe the deactivation behavior adequately. The deactivation rate constant was found to increase with increasing levels of feed oxygen. Hydrogen peroxide was found to deactivate the enzyme severely and the deactivation rate constants were higher than those for oxygen deactivation. The influence of external and internal diffusion effects on the deactivation rate constant were examined. Although diffusional restrictions were negligible for oxygen transfer to the pellet, they were significant for transfer of hydrogen peroxide to the bulk stream. Increasing deactivation rates. Severe internal diffusion limitations were observed for the glucose oxidase system. However, for particle sizes in the range of 500 to 2000 μm, no effect on the rate of deactivation of the enzyme was observed.
Automatic assay of cellulase activity during fermentation
Authors: Leisola Matti , Kauppinen Veli
Published: December 2004

An automatic method using dyed cellulose as a substrate was developed to determine the solubilizing activity of a cellulase complex. The automatic analyzer was connected to a fermentor and enzyme activity was successfully assayed during fermentation. A useful sampling arrangement was developed and the analysis was sensitive enough to make a short reaction time possible. Cellulase production with Trichoderma viride was used as a model process.
Synthetic media for production of quality xanthan gum in 20 liter fermentors
Authors: Cadmus M. C. , Knutson C. A. , Lagoda A. A. , Pittsley J. E. , Burton K. A.
Published: December 2004

Xanthan gum is a heteropolysaccharide synthesized by Xanthomonas campestris NRRL B‐1459 and is composed of D‐glucose, D‐mannose, and D‐glucuronic acid, in addition to acetic and pyruvic acids. Different amounts of pyruvic acid ketal are found in various preparations which can influence the viscosities of dilute xanthan solutions. Polysaccharide production on synthetic media was studied in small‐scale fermentors. Fermentation conditions were established for production of both high and low pyruvic acid gums (about 4 and 2% pyruvic acid, respectively). Low nitrogen [0.1% (NH4)2HPO4] and air (0.25 vol/liter/min) levels favor production of low pyruvate gum; increasing (NH4)2HPO4 to 0.15%, adding K2HPO4, and increasing the air flow to 1.5 vol/liter/min favored production of normal gum. Both processes gave xanthan yields of 50 to 60%, based on 2.5% initial D‐glucose substrate, in two to three days. Differences in pyruvic acid content and in the quantity of gum produced under a given set of conditions were attributed to strain variability. Substrains were isolated that have desirable characteristics for production of xanthan gum; i.e., the ability to give good yields of high‐pyruvate gum when grown on both complex and synthetic media.
Studies on the stability of immobilized xanthine oxidase and urate oxidase
Authors: Johnson D. B. , Coughlan M. P.
Published: December 2004

The stability of immobilized preparations of xanthine oxidase and urate oxidase was studied, and optimized, because of the potential joint use of both enzymes in clinical analysis. Xanthine oxidase was immobilized on cellulose, Sepharose, hornblende, Enzacryl‐TIO, and Porous glass. The half‐lives of these preparations at 30°C ranged from 40 min to 5.0 hr. In this respect immobilized enzyme resembled soluble enzyme in dilute solution (0.11 mg/ml), when the half‐live was about 3.5 hr. More concentrated enzyme solution (1 mg/ml), had a half‐life of 64 hr, and was, therefore, considerably more stable than the untreated immobilized xanthine oxidase preparations. Inclusion of albumen in storage and assay buffer increased the half‐life of bound xanthine oxidase. So also did treatment with glutaraldehyde: in the case of xanthine oxidase bound to Enzacryl‐TIO such treatment increased the half‐life at 30°C from 3 hr to about 100 hr. Immobilized xanthine dehydrogenase was more stable than immobilized xanthine oxidase: the dehydrogenase lost no activity during continuous assay for 5 hr at 30°C. The stability of immobilized urate oxidase depended on the quantity of enzyme used and on the time of stirring during immobilization: thus a preparation was made (by stirring urate oxidase (48 mg/g support) with Enzacryl‐TIO for 24 hr) which lost no activity during 350 hr at 30°C.
Immobilization of immunoglobulins on polystyrene latex beads: Characterization by density gradient centrifugation
Authors: Genung Richard K. , Hsu Hsien‐Wen
Published: December 2004

Isopycnic banding by density gradient centrifugation was used to measure density changes in complexes formed by the immobilization of each of four different immunoglobulins (IgG) (bovine, dog, rabbit, and sheep) on polystyrene latex beads (0.109 ± 0.0025 μm diam). Subtractive measurements of density changes allowed calculation of the mass of immobilized lgG under varying experimental conditions. The immobilization data were correlated with adsorption isotherms which incorporated charge repulsion forces. The effects of pH and NaCl concentration on the immobilization were studied for the latex–bovine lgG system. It was found that the mass of immobilized immunoglobulins was increased from 10 to 20% by removing the lgG from its isoelectric range.
Design, construction, and operation of some all‐glass pilot‐plant fermetors
Authors: Baker K.
Published: December 2004

The design, Construction, and operation of a 400 liter all‐glass fermentor, made from industrial glass Components, is described in detail. Outline details are also given for 100 and liter vessels of similar construction. The performance of the 400 liter fermentor with a variety of organisms is discussed. Harvesting performance. Using a disk‐stak centrifuge, is also described.
Response to various shock loadings of the constant recycle‐sludge‐concentration activated‐sludge process
Authors: Yang P. Y. , Thavinpipatkul Amnuay
Published: December 2004

The stability of the model of a completely mixed activated‐sludge process holding the recycle sludge concentration, XR, as a system constant subjected to pH, temperature, potassium cyanide, and phenol shock loading was investigated. Soft‐drink bottling wastewater was used and maintained at 1000 mg/liter chemical oxygen demand (COD). The hydraulic ratio and recycle sludge concentration were maintained at 0.3 and 7000 mg/liter, respectively. An initial dilution rate of ¼ hr−1 was maintained for pH and temperature shock loading, with ¼ and ⅛ hr−1 for KCN shock loading and ¼, ⅛, and \documentclass{article}\pagestyle{empty}\begin{document}$\frac{1}{16}$\end{document} hr−1 for phenol shock loading. It was found that the present system could handle pH shock loading as low as 4.0 and as high as 10.4 without any serious disruption of biological solid concentration and filtrate COD. At pH 4.0 shock loading, filamentous organisms were predominant. Temperature shock loading could be handled from 23 to 36°C without any leakage of effluent filtrate COD. At 46°C temperature shock, a 14 hr period was required to recuperate to the new steady state and provided only 85% of COD removal efficiency. For KCN (50 mg/liger) and phenol (85 mg/liter) shock loading, the dilution rates should be lower than \documentclass{article}\pagestyle{empty}\begin{document}$\frac{1}{16}$\end{document} hr−1 in order to shorten the transient period and improve the effluent quality. Biological kinetic constants included cell yield value, maximum growth rate, and the saturation constant, which was varied with the qualitative shock applied.
Production of citric acid in batch culture
Authors: Kristiansen B. , Sinclair C. G.
Published: December 2004

Work has been carried out on the production of citric acid in batch culture using Aspergillus foetidus. It is shown that the dry weight increases throughout the fermentation. The supply of nitrogen is exhausted early and the subsequent increase in dry weight is due to accumulation of carbon by the cells. It appears that the exhaustion of nitrogen is a necessary prerequisite for the production of citric acid, which is produced by carbon‐storing cells. The pH history in the early part of the fermentation did not affect the final yields.
Solid‐state cultivation of Chaetomium cellulolyticum on alkali‐pretreated sawdust
Authors: Pamment N. , Robinson C. W. , Hilton J. , Moo‐Young M.
Published: December 2004

Solid‐state fermentations (78% initial moisture content) of alkali‐pretreated Eastern Hard Maple sawdust were conducted in tray and tumble fermentors using chaetomium cellulolyticum. Crude protein content of the solids rose from 0.9 to 11% in the tray fermentor and 8% in the tumble fermentor in 20 days. These levels were almost equal to those achieved in corresponding slurry‐state fermentations (1–5% (w/v)) of the same substrate. Specific growth rates were two to four times lower in the solid‐state fermentors but this was offset by their greater solids‐handling capacity: the rate of protein production per unit volume of fermentation mixture was comparable to that of the 5% (w/v) slurry and two to three times higher than that of the 1% (w/v) slurry.
Generalized rate equation for one‐substrate enzymatic reactions
Authors: Siimer Enn
Published: December 2004

A generalized rate equation for formally two‐step enzymatic reaction has been derived. In this derivation the reaction rate has been regarded as a function of substrate conversion. Applications of this equation to reactor operating parameters and productivity calculations are presented and discussed.
Procedure for the simultaneous large‐scale isolation of pullulanase and 1,4‐α‐glucan phosphorylase from Klebsiella pneumoniae involving liquid–liquid separations
Authors: Hustedt H. , Kroner K. H. , Stach W. , Kula M.‐R.
Published: December 2004

A procedure for the simultaneous large‐scale isolation of pullulanase and 1,4‐alpha;‐glucan phosphorylase from Klebsiella pneumoniae is described. The pullulanase is solubilized from the cell wall by cholate treatment; cells and cell debris are removed by partition in a poly(ethylene glycol) (PEG)‐dextran two‐phase system and from the upper (PEG) phase of this system the pullulanase is isolated by ultrafiltration and precipitation with N‐cetyl,N‐,N‐,N‐trimethyl ammonium bromide to a purity of about 80% with a yield of 70%. The preparations are free of α‐amylase activity. The cell containing dextran‐rich phase is passed through a Manton‐Gaulin homogenizer. Then the phosphorylase is separated from the cell debris by partition in a second PEG‐dextran system. From the top phase of this system the phosphorylase is isolated by distribution in a PEG‐salt two‐phase system followed by batch adsorption on carboxymethyl‐Sephadex in a yield of 55%, a purity of around 90%, and nearly free of glycosyltransferase activity. All steps in the isolation of the two enzymes can be performed easily in a large scale.
Affinity chromatography of endoglucanase of Trichoderma viride by concanavalin A–agarose
Authors: Gong Cheng‐Shung , Chen Li Fu , Tsao George T.
Published: December 2004

Endoglucanase (Cx cellulase) and cellobiase are often cross‐contaminated in separation procedures by ion‐exchange chromatography such as DEAE‐cellulose. By using concanavalin A (Con A)–agarose chromatography, Cx cellulase and cellobiase from Trichoderma viride can be separated. Cx cellulase showed affinity toward Con A, indicating a glycoprotein containing α‐D‐mannopyransyl and α‐D‐glucopyranosyl end groups or internal 2‐O‐D‐mannopyranosyl residues in sugar moieties. This method provides a way to estimate the quantities of Cx enzyme produced by T. viride and possibly by other organisms.
Biological particles of given size, shape, and density for use in biological reactors
Authors: Atkinson B. , Black G. M. , Lewis P. J. S. , Pinches A.
Published: December 2004

Novel biomass support particles containing growing cells have been developed for use in large‐scale fermentation processes. The characteristic size of the entrapped biomass is identical to that of the physical structure of the support particle, and particles can be produced of any size, shape, and density with a wide variety of microorganisms. Use of the particles in fermentors leads to high biomass concentration independent of throughput, predetermined biomass concentrations, the use of novel types of fermentor with advantageous performance characteristics, possibilities for the optimization of advantageous diffusion effects, and new procedures for biomass recovery.
Production of citric acid in continuous culture
Authors: Kristiansen B. , Sinclair C. G.
Published: December 2004

Work has been carried out on the production of citric acid by Aspergillus foetidus in single‐stage continuous culture, operated under nitrogen‐limiting conditions at dilution rates between 0.04 to 0.21 hr−1. Citric acid concentration increased rapidly as the dilution rate decreased and appears to be critically dependent on the pH in the culture vessel and the nitrogen concentration in the feed. A mathematical model based on a distinction between basic cells, which require nitrogen but do not produce citric acid, and stroage cells, which accumulate carbon and simultaneously produce citric acid, is proposed.
Design of scraped tubular fermentors
Authors: Moo‐Young M. , Van Dedem G. , Binder A.
Published: December 2004

Conventional stirred‐tank fermentors are inefficient in carrying out certain fermentation processes because of one or more of the following constraints: media backmix–flow, solids wall–deposits, microbial growth–disruption. Two series of novel design of aerated scraped tubular fermentors have been developed to over come the deleterious effects of these constraints. One design is based on a horizontal tube fitted with an internal mechanical wall‐scraper that also promotes media segregation; the other design is based on a vertical array of vessels interconnected by small gas‐jetting orifices that promote media segregation and clean‐surface operation. Tests with cultures of Trichdorma viride (for single‐cell protein production) and Candida lipolytica (for lipase production) have been carried out. It is shown that these novel fermentors can minimize the effects of catabolite repression inherent in both cultures and of wall growth in the former.
Investigation of the significance of a carbon and redox balanced to the measurement of gaseous metabolism of Saccharomyces cerevisiae
Authors: Barford J. P. , Hall R. J.
Published: December 2004

A complete carbon and redox balance for Saccharomyces cerevisiae grown in batch culture with ethanol as the limiting carbon and energy source is reported. A novel method, which allowed the determination of carbon dioxide contained in the culture medium and biomass, is described and revealed amounts considerably in excess of what was expected from equilibrium data. Furthermore, elemental composition of the biomass was used to calculate the amount of oxygen required for biosynthetic reactions. When these corrections are applied to experimentally measured gas metabolism data, apparently anomalous results are shown to be consistent with the overall metabolism of bakers' yeast. These findings have wide implications to the quantitative study of the metabolism and energetics of facultative aerobes.
Effect of growth rate on the amino acid composition of Fusarium moniliforme cultivated continuously for fungal protein production
Authors: Macris B. J. , Kokke R.
Published: December 2004

Fusarium moniliforme was shown to be a promising fungus for microbial protein production. 1−3The fungus grows well on the aqueous extracts of carob pods, a low value agricultural product well known in the Mediterranean areas. In a previous paper2quantitative data were presented on the production of fungal protein by growing F. moniliforme on a carob aqueous extract in a continuous culture. In the present paper the amino acid profile of the biomass was determined and the resulting essential amino acid index was calculated.
Reactor properties of a high‐speed bead mill for microbial cell rupture
Authors: Limon‐Lason J. , Hoare M. , Orsborn C. B. , Doyle D. J. , Dunnill P.
Published: December 2004

Laboratory and pilot‐plant high‐speed bead mills of 0.6 and 5 liter capacity and consisting of four and five impellers in series, respectively, were used to follow the batch and continuous disruption of bakers' yeast (Saccharomyces cerevisiae). The mills are not scaled equivalents. Throughputs ranging from 1 × 10−6m3/sec to 12 × 10−6m3/sec for the 0.6 liter mill and from 16 × 10−6m3/sec to 100 × 10−6m3/sec for the 5 liter mill were used for continuous disruption studies. Variables studied included the effect of impeller tip speed, temperature, and packed yeast concentration (ranging from 15 to75% by weight packed yeast). Disruption kinetics, as measured by the release of soluble protein, followed a first‐order rate equation, the rate constant being a function of impeller tip speed and yeast concentration. For continuous disruption studies the bead mills behaved as a series of continuous stirred‐tank reactors, each impeller forming a reactor. In the smaller mill a considerable degree of backflow between the reactors was evident. For certain mixing conditions the maximum amount of releasable protein was dependent on the impeller geometry, construction material, and also the concentration of packed yeast. The relative power efficiencies of the two mills are discussed along with possible criteria for scaling of bead mills.
Preparation and properties of an immobilized derivative of penicillinase
Authors: Klemes Yoel , Citri Nathan
Published: December 2004

Penicillinase (β‐lactamase I, EC 3.5.2.6)secreted by Bacilluus cereus, strain 569/H, was covalently attached to aminoethyl cellulose via glutaraldehyde. The immobilized derivative shows increased thermostability and decreased susceptibility to conformational changes induced by certain substrates of penicillinase. The decline in the rate of such substrates was consequently suppressed by immobilization. A marked increase in Km was observed with all substrates except for the unsubstituted 6‐aminopenicillanic acid. The altered properties of the new derivative are attributed to the constraint imposed by immobilization on the conformational flexibility of the enzyme molecule. Thus, apart from obvious technological interest, immobilized penicillinase provides a useful model for the study of the role of flexibility in the function of an enxyme.
Biological production of methane from energy crops
Authors: Clausen E. C. , Sitton O. C. , Gaddy J. L.
Published: December 2004

Laboratory studies at the University of Missouri‐Rolla have demonstrated the feasibility of producing methane by anaerobic digestion of various of crop materials, such as grasses and corn stalks. These studies indicate that up to 6.0 f3methane are produced/b crop material destroyed. Preliminary design and economic studies of a large methane plant show that the reactors represent the largest cost item and that efforts should be concentrated on defining reaction kinetics and reactor design. A process to produce 50 M̄ f3methane/day is described, and the preliminary design and economics are analyzed.
Production of single cell protein from ethanol by fed‐batch process
Authors: Watteeuw C. M. , Armiger W. B. , Ristroph D. L. , Humphrey A. E.
Published: December 2004

The production of single cell protein (SCP) form ethanol is an interesting process to study from a biochemical engineering viewpoint. The cellular yield mainly depends upon the metabolic activity of the cells and the amount of substrate available. Fedbatch fermentations Were run in a 70 liter highly instrumented computer‐coupled fermentor using Candida utilis. Respiratory quotient and culture fluorescence, measuring NADH, indicate by which pathway ethanol is utilized. By monitoring these parameters it is possible to control the ethanol concentration so that accumulation of acetate is minimized and the conversion of ethanol to cell mass is maximized.
On‐line identification of parameters in a fermentation process
Authors: Bravard J. P. , Cordonnier M. , Kernevez J. P. , Lebeault J. M.
Published: December 2004

In a fermentation process, the establishment of gas mass balances provides valuable information and allows both measurements concerning the characteristics of the biomass itself and the monitoring of a cultivation process. If the quantity and oxidation level of substances excreted into the fermentation broth are known or constant, the yield factor and the dry cell‐weight production are stoichiometrically related to the quantity of CO2 evolved and to the quantity of O2 consumed. Where frequent measurements of both yield factor and dry cell‐weight production are desirable or where rapid adjustment of the parameters is necessary, on‐line identification of these parameters is required, An algorithm allowing the identification of the specific growth rate is presented. Moreover, this technique allows one to estimate the percent protein in the biomass during continuous culture.
Secretion of cellulase and β‐glucosidase by Trichoderma viride ITCC‐1433 in submerged culture on different substrates
Authors: Herr Dieter
Published: December 2004

Trichoderma viride ITCC‐1433 produces high yields of cellulase and especially β‐glucosidase when grown in submerged culture on different carbon sources. Cellulase synthesis was strongly repressed in the presence of glucose and only a low constitutive activity of β‐glucosidase and carboxymethylcellulase, but no Avicelase, could be demonstrated when culturing T. viride on glucose. With carboxymethylcellulose (CMC) as a substrate the secretion of enzyme as well as growth depended on the degree of substitution, but in general CMC cannot be regarded either as a powerful inducer or as a carbon source. With insoluble cellulose, maximum enzyme production and activities were obtained using an alkali‐treated cellulose powder. On this substrate the excretion of soluble protein into the culture broth increased and the protein concentration corresponded to cellulolytic activities.
Role of agitation conditions in nitrification
Authors: Novak Lawrence T.
Published: December 2004

The objective of this study was to determine the role of agitation conditions in the oxidation of nitrite ions by Nitrobacter. Batch reaction kinetic experiments were conducted in baffled stirred tanks. The range of agitation conditions studied was 6200 ↔ 95700 ergs/cm3 sec. This power input corresponds to 3.2 ↔ 45.6 hp/ 1000 gal, or a “hem Scale” of 3 ↔ 9. After a lag phase, the reaction kinetics were found to be zero order with respect to nitrite over a concentration range of 590 to 10 mg/liter nitrite nitrogen (NO2−‐N). The zero‐order rate constants were found to significantly decrease with increasing impeller power input per volume of liquid (P / V).
Cost‐effective dissolved oxygen monitor–controller for continuous culture
Authors: Archibald Frederick
Published: December 2004

A number of devices for the control of the dissolved oxygen (DO) tension in small continuous cultures are now in use, but because of the sophisticated proportional control employed, are prohibitively expensive for many applications. This report describes a flexible cost‐efficient DO monitor and controller which, including DO probe, valves, and gas solenoid, can be constructed for 400 dollars. The device employs two‐position control of gas flow and agitation speed and is readily adaptable to a variety of application; Construction, operation, and performance in conjunction with a small fermentor are briefly discussed.
Preparation and properties of immobilized flavokinase
Authors: Merrill Alfred H. , McCormick Donald B.
Published: December 2004

Flavokinase (ATP: riboflavin 5'‐phosphotransferase, EC 2.7.1.26) purified from rat liver by affinity chromatography, has been immobilized by amide linkage to aminoalkyl‐agarose beads. The immobilized enzyme differs from the soluble enzyme in having greater stability slightly higher Km for the substrates, riboflavin and ATP, a broader pH optimum, and a lower energy of activation. These results suggest that the immobilized enzyme is influenced by the microenvironment of the bead and is subject to some degree of internal diffusional limitation. A Small (3ml), continuous, plug‐flow reactor prepared with immobilized flavokinase effects 5% conversion of riboflavin to riboflavin 5′‐phosphate (FMN) with a flow rate of 0.16 ml/min, which corresponds to an output of 5 nmol FMN/min. Immobilized flavokinase is effective for phosphorylating riboflavin and numerous riboflavin analogs and provides a facile methods for preparing exclusively, unlike other synthetic methods, the 5′‐phosphates.
Degradation of ribonucleic acid by immobilized ribonuclease
Authors: Dale Bruce E. , White Don H.
Published: December 2004

An immobilized enzyme (pancreatic ribonuclease bound to porous titania) was investigated for the degradation of purified yeast ribonucleic acid as a substrate. The immobilized enzyme is active and stable in the pH range 4–8. Dependence of enzymatic activity on ionic strength, pH, temperature, fluid flow rate, and substrate concentration were investigated. A cummulative fluid residence time of 6 sec is sufficient for 5% substrate conversion at 25°C and pH 7.0. The critical flow rate (i.e., the fluid flow rate necessary to remove film diffusion resistance) approximately doubles with each 10°C rise in reaction temperature. The critical flow rates obtained in this study are about 40 times greater than those obtained for a similar study on immobilized glucose oxidase. Arrhenius plots gave activation energies of −9.6 and −7.1 kcal/g mol at pH 4.6 and 7.0, respectively. The work reported herein is a bench‐scale investigation of an immobilized enzyme with primary emphasis on the mass transfer and kinetic characteristics of the system. The rapid reaction rates obtainable at relatively low temperatures offfer a potential alternative method of purifying yeast single cell protein (SCP) with minimum loss of desired protein. The key questions are how such a system would react in a yeast homogenate, what conditions in such a system must be controlled, and what type of immobilized reactor should be utilized, if such further work continued to show promise.
Effect of PO2 on growth and physiological characteristics of Candida utilis in a multistage tower fermentor
Authors: Páca Jan , Grégr Vratislav
Published: December 2004

The effect of increasing the partial pressure of oxygen in the aeration gas on growth and physiological activity of the yeast Candida utilis in a multistage tower fermentor was studied. The measurements were made at steady states of continuous culture for single values of dilution rate, temperature, and pH in all stages of the fermentor and with one given ethanol concentration in the growth medium feed. The partial pressure of oxygen in the gas phase was changed in the range from 165 to 310 torr. The results revealed the existence of the upper critical value of the partial oxygen pressure in the gas phase. It was demonstrated that the upper critical value of PO2 influences not only the growth rate, biomass yield, and productivity but also the cell physiology resulting in changes of respiration activity and activity of alcohol and aldehyde dehydrogenases.
Evaluation of data consistency and estimation of yield parameters in hydrocarbon fermentations
Authors: Ferrer Alexis , Erickson L. E.
Published: December 2004

The consistency of experimental data for hydrocarbon fermentations is reviewed using carbon and available electron balances and the mean values of the regularities for carbon weight fraction in biomass and biomass reductance degree. True growth yields and maintenance coefficients are estimated from both batch and continuousculture data and the results are compared.
Hydrolysis of organophosphate insecticides by an immobilized‐enzyme system
Authors: Munnecke D. M.
Published: December 2004

An enzyme preparation that could detoxify parathion and eight other organophosphate pesticides was covalently bound to either porous glass or porous silica beads. This immobilized‐enzyme system was examined for its use in detoxification of pesticides in production wastewaters. The kinetics of parathion hydrolysis were examined at flow rates up to 96 liter/hr and at influent substrate concentrations ranging from 10–250 mg/liter. The enzyme reactor was able to hydrolyze 95% o1r more of the parathion added to industrial wastewaters generated during its production, thus reducing the effluent parathion concentration to below 500 ppb. Laboratory continuous‐flow experiments were conducted for 70 days with industrial wastewater and indicated no loss in immobilized‐enzyme activity. The influence of pH, temperature, solvents, and detergents on enzyme stability and activity and enzyme reactor kinetics will be discussed.
On‐line estimation of kLa by an analog computer
Authors: Yoshida Toshiomi , Ohasa Sugayuki , Taguchi Hisaharu
Published: December 2004

A new method was developed for estimating the volumetric oxygen transfer coefficient, kLa, in a fermentor. Various methods were investigated for the on‐line estimation of kLa with an analog computer employing a steepest‐descent calculation technique. The method by which kLa is estimated (by minimizing the error residue of the model) was found to be very applicable. A method for the simultaneous estimation of the volumetric oxygen transfer coefficient and respiration rate in biological systems is also presented.
Quantitative physiology of Penicillium chrysogenum in penicillin fermentation
Authors: Ryu Dewey D. Y. , Hospodka J.
Published: December 2004

Using continuous and fed‐batch penicillin fermentation systems some important metabolic parameters have been determined for the purpose of achieving process improvement and better process control. The specific uptake rates determined under the optimal conditions are: 0.33 mmol hexose/g cell/hr, 1.6 mmol oxygen/g cell/hr, 2mg NH3‐nitrogen/g cell/hr, 0.6 mg PO4‐phosphorus/g cell/hr, 2.8 mg SO4‐sulfur/g cell/hr, 1.8 mg phenyl acetic acid/g cell/hr. It was also found that during the production phase, or idiophase, the specific growth rate should be maintained at about 0.015 hr−1 in order to support the maximum penicillin productivity of the given strain. Based on the results of this study a significant process improvement has been achieved through proper control of the supply and demand of the important nutrients and oxygen.
Studies of growth conditions in wood for three white‐rot fungi and their cellulaseless mutants
Authors: Eriksson Karl‐Erik , Grünewald Annette , Vallander Lars
Published: December 2004

White‐rot fungi, which have the ability to degrade all the wood components including lignin, are of great interest in biotechnological processes based on wood and other lignocellulosic materials. It was demonstrated earlier that enough lignin can be degraded to cause a decrease in the energy demand for production of thermomechanical pulp if wood chips are pretreated by cellulaseless mutants of white‐rot fungi. This paper concerns the growth conditions in wood for three white‐rot fungi and their cellulaseless mutants in order to determine optimal conditions for such pretreatment processes. The pH and temperature optima have been determined as well as the growth rate in wood. The results show that the growth rate in wood. at least for Cel 44 (a cellulaseless mutant of Sporotrichum pulverulentum), is not the rate‐limiting step in delignification. From different mixtures of urea and NH4H2PO4 the optimal nitrogen source was determined for the mutants. The optimal C/N ratio was found to vary between 160/1 and 400/1. It is suggested that the lower the C/N ratio, the faster the growth. It was also demonstrated that both water‐ and acetone‐extractable substances in wood supported the growth of cellulaseless mutants. When some glucose was added to the wood, the weight loss caused by Cel 44 increased. All these observations support earlier findings that lignin in wood cannot be degraded by white‐rot fungi unless a more easily metabolizable carbon source is used simultaneously.
Lactic acid fermentation of crude sorghum extract
Authors: Samuel William A. , Lee Y. Y. , Anthony W. B.
Published: December 2004

Crude extract from sweet sorghum supplemented with vetch juice was utilized as the carbohydrate source for fermentative production of lactic acid. Fermentation of media containing 7%(w/v) total sugar was complex completed in 60–80 hr by Lactobacillus plantarum, product yield averaging 85%. Maximum acid production rates were dependent on pH, initial substrate distribution, and concentration, the rates varying from 2 to 5 g(liter·hr.) The lactic acid yield was lowered to 67% under limited medium supplementation. The fermented ammoniated product contained over eight times as much equivalent crude protein (N × 6.25) as the original medium. Unstructured kinetic models were developed for cell growth, lactic acid formation, and substrate consumption in batch fermentation. With the provision of experimentally determined kinetic parameters, the proposed models accurately the fermentation process.
Extracellular microbial polysaccharides. I. Substrate, biomass, and product kinetic equations for batch xanthan gum fermentation
Authors: Weiss Rebecca M. , Ollis David F.
Published: December 2004

Various biomass (X), product (P), and substrate (S) rate equations are considered in order to synthesize a general xanthan fermentation model from literature data. Analytical forms that provide reasonable descriptions for the X, P, and S behaviors reported by Moraine and Rogovin are shown to be the logistic equation, the Luedeking–Piret equation a modified Luedeking‐Piret equation, respectively. The autonomous logistic equation allows the serial evaluation of parameters for all thee equations, rather than a simultaneous determination required by nonautonomous models.
Biologically active fluidized beds: Mechanistic considerations
Authors: Ngian K. F. , Martin W. R. B.
Published: December 2004

A postulated model of a biologically active fluidized bed is given, subject to various constraints.
Possible commercial formulations of insect‐parasitic nematodes
Authors: Nickle W. R.
Published: December 2004

At least two experimental nematode biological insecticide formulations are currently being produced in small quantities around the world, These formulations are efficacious and people are willing to pay money for them. Advantages for the use of these parasites can be: nonpolluting, self‐perpetuating, safe, and not harmful to beneficial organisms. The disadvantages are: relatively short shelf‐life, acceptability, moisture, price, and dispersal techniques. One of the preparations is a nematode that vectors a bacterium. It can be produced at the rate of 100 × 106 infective nematodes/2 liter container at a cost of 2 cents/106. It can kill over 1000 species of insects. The other product kills over 60 species of mosquitoes and has been sold as mermithid nematode eggs in moist sand. This mosquito parasite can be established in the new site and self‐perpetuate to suppress mosquito parasite can be established in the new site and self‐perpetuate to suppress mosquito populations. It kills the mosquito before pupating. Increased research activity, using these parasites in the last ten years, has stimulated interest in these organisms for pest insect control.