bluuebunny/crossref_metadata_2025 huggingface dataset:
Continuous production of NADP by immobilized Achromobacter aceris cells
Authors: Uchida Tomofumi , Watanabe Taizo , Kato Jyoji , Chibata Ichiro
Published: December 2004

Several microorganisms having higher nicotinamide adenine dinucleotide kinase (NAD kinase, EC 2.7.1.23) activity were immobilized into polyacrylamide gel lattices. The enzyme activity yield by immobilization was highest in Achromobacter aceris AKU 0120. By the incubation of the immobilized A. aceris cells at pH 4.0, the NAD kinase activity increased and the adenosine triphosphate(ATP)‐degradation activity disappeared completely. Enzymic properties of the immobilized A. aceris cells were investigated and compared with those of intact cells. The optimal pH and the optimal temperature of immobilized cells were the same as those of intact cells. Immobilized cell NAD kinase was more stable than that of intact cells. The operational half‐life of immobilized cells was 20 days when the substrate solution was passed through a column packed with immobilized cells at a flow rate which gives a space velocity (SV) of 0.1 hr−1 at 37°C. On the other hand, the half‐life of the intact cells was only 6 hr.
Preparation and properties of immobilized methanol oxidase
Authors: Baratti J. , Couderc R. , Cooney C. L. , Wang D. I. C.
Published: December 2004

Methanol oxidase produced by the yeast Hansenula polymorpha DL‐1 was used for the enzymatic oxidation of methanol to formaldehyde. The kinetics of enzyme and protein release during cell desruption were studied at the laboratory scale with a Braun homogenizer and the pilot plant scale with a Manton–Gaulin homogenizer. Conditions were defined for maximum release and retention of high activity in cell‐free extracts. Methanol oxidase was immobilized by adsorption on DEAE‐cellulose from enzymes in cell‐free extracts or from ammonium sulfate purified purified fractions. The kinetics of formaldehyde formation with both soluble and immobilized enzyme was studied in batch and continuous reactors.
Effect of refiner defibrizing on the fermentability of ryegrass straw
Authors: Han Y. W. , Chen W. P. , Miles T. R.
Published: December 2004

The effects of two grinding methods, hammer milling and defibrizing by disk refining, on the fermentability of ryegrass straw were investigated. Disk refined or defibrized straw produced more sugar than hammer milled straw. Release of sugar was especially pronounced when H2SO4 was added to the straw during the defibrizing process. In vitro rumen digestibility was significantly higher (P < 0.1) for defibrized than for hammer milled straw. With semisolid culture the level of yeast growth was about three times as high on the defibrized as on hammer milled straw. A scanning electron micrograph revealed that defibrizing removed the waxy surface of the straw as well as separating fiber bundles, so that the surface area of the exposed fiber structure was increased.
Coprecipitation of acid cheese whey and tannery waste and recovery of protein
Authors: Townend Robert E.
Published: December 2004

Combining acid cottage cheese whey and the lime–sulfide effluent from tannery unhairing processes spontaneously coprecipitates the whey proteins with the large peptides and proteins of the tannery waste. The floculation of the denatured protein material also carries down the hide pigments, excess lime, and the casein fines from the whey. The clear supernatant contains lactose, sulfur in various states of oxidation, free amino acids, peptides, and ammonium salts, but no detectable macromolecular proteins. The recovered solid products, which contain more than 20% of the original nitrogen, appear to have a good balance of essential amino acids although actual composition varies with the composition of the raw wastes. Feed supplements may possibly by obtained by this method from two presently wasted industrial effluents.
Immobilization of Streptomyces flavochromogenes pullulanase on tannic acid and TEAE–cellulose
Authors: Ohba Riichiro , Chaen Hiroto , Hayashi Sachio , Ueda Seinosuke
Published: December 2004

Pullulanase was immobilized successfully by simple, inexpensive methods that may be useful for industrial application of this enzyme. A tannin–pullulanase(TP) complex was obtained by addition of tannic acid to the culture filtrate of thermophilic Streptomyces flavochromogenes. TP could be bound to TEAE–cellulose (TTCP). Immobilization in this manner took place with quantitative retention of activity. The immobilized enzymes were stable for more than six months. The optimum temperatures of the native enzyme and TP were both 50°C; that of TTCP was 45°C. In the presence of 5mM Ca2+, the activity of TTCP was increased approximately twofold and the optimum temperature was raised to 50–60°C. Pullulanase was not significantly eluted from TP or TTCP by NaCl Solution (0.1–0.5M).
Enhancement of oxygen absorption into sodium sulfite solutions
Authors: Linek V. , Beneš P.
Published: December 2004

Oxygen absorption enhancement in a sodium sulfite solution was studied in the absence and presence of copper catalyst both for absorption across the liquid surface in a stirred cell and for absorption from individual bubbles rising through a turbulent liquid. The enhancement factor was determined from the ratio of oxygen and argon mass transfer coefficients, measured under identical experimental conditions in the same batch of liquid. It has been found that the oxygen absorption is not chemically enhanced, as long as the mass transfer coefficient, kL0, is high enough, i.e., higher than the value 1.4 × 10−4 m sec−1 for the sulfite solution we used. An analysis of our data as well as literature data indicates that the sulfite system is poorly suited for studies of the volumetric mass transfer coefficient of physical absorption (kL0a) in fermentors, inasmuch as oxygen absorption can be chemically enhanced while the degree of enhancement depends on the operating conditions of batch aeration, as well as on the concentration of trace impurities with catalytic effects upon the sulfite solution used.
The rotorfermentor. II. Application to ethanol fermentation
Authors: Margaritis Argyrios , Wilke Charles R.
Published: December 2004

The kinetics of microbial growth and product formation are described as applied to the high cell concentration scheme of the rotorfermentor. A bench scale pilot plant was designed and built in order to demonstrate the operational feasibility of the rotorfermentor. The fermentation of glucose to ethanol by Saccharomyces cerevisiae ATCC 4126 was used. When the rotorfermentor was used with a glucose feed concentration of 104 g/liter almost 100% glucose utilization was obtained and the ethanol productivity rate was 27.3 g ethanol/liter hr which was found to be about 10 times greater than the ethanol productivity obtained from an ordinary continuous stirred tank (CST) Fermentor. The ethanol experimental results obtained from the rotorfermentor and an ordinary CST fermentor were used as a basis to assess the economic feasibility of the rotorfermentor. The economics of an industrial scale ordinary CST fermentor with and without cell recycle is compared with a rotorfermentor unit for the same ethanol production throughput. For the process conditions considered on this case, calculations showed that the rotorfermentor may replace both a CST fermentor and cell centrifuge resulting in lower capital equipment costs and lower power consumption requirements.
Enzyme deactivation during cellulose hydrolysis
Authors: Howell J. A. , Mangat M.
Published: December 2004

Hydrolysis of cellulose by Trichoderma viride cellulase reached a plateau after some 25 hr. If the initial enzyme‐to‐substrate ratio was low, resuspension of substrate in fresh enzyme or addition of enzyme resulted in further high rate hydrolysis. This did not occur if the initial ratio was high. Over 75% hydrolysis might be achieved in the former case, while less than 60% in the latter. A model postulating inactivation of adsorbed enzyme–substrate complex which blocked further hydrolysis was proposed, and it was found to fit the data well. The proposed model had five parameters, four of which could be checked by graphical methods, and all of which had physical meanings. The parameters were estimated by a nonlinear least‐squares minimization FORTRAN computer program, using numerical integration and optimization of the parameters. The model was used to predict the resuspension data, powdered enzyme addition data, cellobiose addition data, and cellulose addition data; the deviations from the model are discussed. It was found that average values could be used for four out of the five parameters, while the fifth (initial enzyme concentration) did not correlate with independent measurements such as the filter paper activity or protein concentration.
Continuous fractionation of human plasma
Authors: Mitra Gautam , Lundblad John
Published: December 2004

Continuous processing has been applied to human plasma fractionation by the cold ethanol process. On‐line pH control of ±0.05 pH units, flow control of ±1%, and temperature control of ±0.5°C have been achieved. Optimization of precipitation pHs has been carried out for purifying plasma protein fractions and albumin. During precipitation, the irreversible nature of the pH overshoots has been demonstrated. Compared to the batch processing mode, the continuous scheme produces an increased yield between 6 to 11%.
Effect of inoculum size on the aeration pattern of batch cultures of a fungal microorganism
Authors: Brown D. E. , Zainudeen M. A.
Published: December 2004

Trichoderma reesei QM 9123 has been grown in batch culture in a 10 liter stirred fermentor, at a temperature of 30°C and pH 4.0. The fermentor was operated at a single stirrer speed of 400 rpm and air rate of 1 v/v/m. The effect of four inoculum sizes (0.5, 1.0, 3.0 and 5.0%) on the growth pattern and the aeration profiles was examined. Logarithmic growth of the fungus was observed. The aeration profile changed with inoculum size and at 5.0%, it was found that the oxygen uptake rate was controlled by the oxygen supply rate, during which the oxygen tension was zero.
Treatment of primary sewage sludge with enzymes
Authors: Knapp Jeremy S. , Howell John A.
Published: December 2004

The effect of cellulase treatment on the physical dewatering of primary sewage sludge has been investigated. Although cellulase treatment rapidly increases the sedimentation rate of diluted sludge, no significant advantage has been found in the settling of undiluted sludge. An extract produced from cellulase‐treated sewage sludge has been used as a medium for the growth of yeast with a view to single‐cell protein production.
Immobilization of glucose isomerase to ion‐exchange materials
Authors: Huitron C. , Limon‐Lason J.
Published: December 2004

Glucose isomerase (D‐xylose ketol‐isomerase EC 5.3.1.5) from Bacillus Coagulans was partially purified and immobilized by adsorption to anion exchangers. The highest activities were obtained when the enzyme was adsorbed to DEAE‐cellulose. On immobilization to DEAE‐cellulose the measured optimum pH value for enzyme activity shifted from 7.2 to 6.8. There was no appreciable difference between the heat stabilities of soluble and immobilized enzyme. The Km app values for the immobilized enzyme were found to be 0.25M in the presence of 0.01M Mg2+ and 0.19M with 0.005M Mg2+, while those enzyme were 0.11 and 0.17M, re spectively. Under conditions of contimuous of D‐glucose, a decrease of activity with time was observed, but this decrease was less at a low Mg2+ concentration and was affected by column geometry. There were no appreciable diffusional limitation effects in packed‐bed columns.
Design and oxygen‐transfer potential of a pulsed continuous tubular fermentor
Authors: Serieys M. , Goma G. , Durand G.
Published: December 2004

A new type of continuous fermentor has been developed which features an agitation‐aeration system based on pulsed flow across perforated plates the use of plug flow to achieve a concentration gradient. The influence of the agitation‐aeration parameters (in this case the pulsed speed) has been measured, and mathematical models have been produced for the gas hold‐up, the power dissipated in agitation and aeration, the oxygen‐transfer rate, and efficiency. The oxygen transfer is high, up to 600 mmol/liter hr with a transfer efficiency much higher than that published for any other technique.
Yeast SCP from ethanol: Measurements, modeling, and parameter estimatin in a batch system
Authors: Prokop A. , Votruba J. , Sobotka M. , Panoš J.
Published: December 2004

The production of single‐cell protein (SCP) from ethanol by different imcroorganisms is briefly reviewed. The trends in modeling the SCP production are outlined with a stress on the need to incorporate metabolic and engineering considerations into the pertinent models. Data on batch yeast growth on ethanol are analyzed, a metabolic model involving design parameters is suggested, parameters values are estimated, and their significance is discussed. The model essentially describes the response of a system to disturbances (substrate, metabolites, oxygen, etc.). An effective numerical integration procedure is necessary in the solution of the model which has “stiff” character.
Mathematical models for hollow‐fiber enzyme reactors
Authors: Webster I. A. , Shuler M. L.
Published: December 2004

Two analytically solved mathematical models are presented for a reactor ystem employing immobilized whole cells as a biocatalyst. The whole cells are entrapped or pumped through the shell side of the dialyzer reactor unit. The reactant mixture is circulated through the cialyzer tube side. Nutrient diffuses across the hollow fiber membrane from the tube side to the shell side, where it reacts to form product, which then back diffuses into the reactant mixture stream. The use of a high recirculation ratio of nutrient through the dialyzer tubes to nutrient feed rate to the entire system, allows the system to be modeled as a continuous‐flow stirred‐tank reactor. The first analysis details the development of an effectiveness‐factor correlation for first‐ and zero‐order kinetics. The second analysis presents the solution to an unsteady‐state‐system mass balance with Michaelis–menten kinetics.
Model for oxygen transfer in a shake flask
Authors: Van Suijdam J. C. , Kossen N. W. F. , Joha A. C.
Published: December 2004

The shake flask is a very common and useful tool for the study of submerged fermentations on a small scale. However, the oxygen supply may easily become a limiting factor. A model for the aeration in shake flasks is presented that enables one to predict whether in the course of an experiment the oxygen supply is becoming a growth‐limiting factor or not. The results of measurements of the transfer coefficient of a cotton plug and the oxygen mass‐transfer coefficient kla are also given.
Hydrocarbon fermentation: Kinetics of microbial cell growth
Authors: Goma Gérard , Ribot Denis
Published: December 2004

Modeling of microbial growth using nonmiscible substrate is studied when kinetics of substrate dissolution is rate limiting. When the substrate concentration is low, the growth rate is described by an analytical relation that can be identified as a Contois relationship. If the substrate concentration is greater than a critical value Scrit, the potentially useful hydrocarbon S* concentration is described by S* = Scrit/(1 + Scrit/S). A relationship was found between Scrit and the biomass concentration X. When X increased, Scrit decreased. The cell growth rate is related to a relation μ = μm[A(X/Scrit)(1 + Scrit/S) + 1]−1. This model describes the evolution of the growth rate when exponential or linear growth occurs, which is related to physico‐chemical properties and hydrodynamic fermentation conditions. Experimental data to support the model are presented.
Continuous culture of Candida lipolytica on n‐hexadecane
Authors: Gutierrez J. R. , Erickson L. E.
Published: December 2004

Candida lipolytica was grown continuously on n‐hexadecane as the main source of carbon. A transient continuous‐culture experiment was also conducted to investigate hydrocarbon‐limited growth; the hydrocarbon feed flow rate was stopped for several hours and then resumed at a reduced steady‐state flow rate. Interfacial tension, Sauter mean diameter, pseudosolubility, fraction of cells in the aqueous phase, oil‐phase volume fraction, and cell concentration were measured to characterize the system. The microorganisms appear to utilize both the submicron drops and the microscopic drops. The effects of interfacial tension, pseudosolubility, and unoccupied interfacial area on the kinetics of hydrocarbon fermentation are discussed here. A conceptual model for hydrocarbon uptake is presented and discussed.
Influence of manufacturing variables on the characteristics and effectiveness of chitosan products. I. Chemical composition, viscosity, and molecular‐weight distribution of chitosan products
Authors: Bough W. A. , Salter W. L. , Wu A. C. M. , Perkins B. E.
Published: December 2004

Ten chitosan products were manufactured from dry shrimp hulls under differing process conditions and compared to a commercially available product. Manufacturing variables tested were: alkali versus enzymatic deproteination; acid demineralization versus no treatment; air versus nitrogen atmosphere; 5 min vs. 15 min deacetylation period: and varying the particle size of the dry starting material. Deproteination by alkali of enzymatic extraction did not substantially affect the nitrogen and ash compositions of dry chitosan samples. However, the viscosity was reduced in samples deproteinated by enzymatic hydrolysis. Elimination of the demineralization step resulted in products having 31–36% ash, as expected. Some differences in viscosity were observed between deminiralized and undemineralized samples, but on important differences in the molecular‐weight distribution of these samples were evident. Purging the reaction vessel with nitrogen resulted in chitosan preparations having higher viscosities and molecular‐weight distributions than those prepared in an air atmosphere. The degradative effect of air became more proshrimp hulls to 1 mm prior to any treatment resulted in a chitosan product of both higher viscosity and molecular weight than when ground to either 2 or 6.4 mm. Viscosity was not always a direct indicator of molecular weight, for although the presence of colloidal particles increased the viscosity of some samples, the molecular‐weight distribution after filtration was essentially the same as in other less viscous samples.
Applied microalgae photosynthesis: Discharge mechanisms in highly illuminated cells
Authors: Contreras S. , Soto M. A. , C. J. Toha
Published: December 2004

Based on the hypothesis that discharge mechanisms are induced in highly illuminated thylakoid, we analyze an applied model, which overcomes the damage induced by outdoor solar radiation, partially shaded, air‐bubbled, or stirred blue‐green algae cultures. The blue‐green alga, Oscillatoria sp., exhibits a maximum growth rate at a radiation intensity of 50 J/m2sec. The introduction of 0.1 sec dark periods shifts this peak up to 75 J/m2sec. The radiationless nature of the discharge mechanisms is discussed in accord with the low growth rates of both the experimental and control cultures at 40°C.
The viscostat: Productstat method of feed‐rate control in continuous fermentations
Authors: Silman R. W. , Bagley E. B.
Published: December 2004

Xanthan biopolymer has been produced in a single‐stage continuous fermentation with Xanthomonas campestirs NRRL B‐1459, using a viscostal control method instead of the conventional chemostat method. A Bendix Ultraviscoson

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sensed the fermentor viscosity, and the recorder–controller actuated the feed medium pump in an on–off control mode. Since all continuous fermentations eventually become contaminated or suffer culture variation, this work served also to demonstrate the effectiveness of the viscostat control. Neither the presence of a mold contaminant with specific growth rates lower than that of X. campestris, nor the presence of a bacterial contaminant of specific growth rate greater than X. campestris, affected the maintenance of constant viscosity in this control system.
Effect of initial substrate concentration on the rate of nitrification in a batch experiment
Authors: Shieh Wen K. , La Motta Enrique J.
Published: December 2004

The intrinsic rate of nitrification was observed in a batch reactor by eliminating external and internal diffusional resistances. The former were minimized by means of intense agitation, and the latter by mechanical rupture of the activated sludge flocs using high mixer rotational speeds. The optimum temperature and pH for the intrinsic nitrification rate were found to be 30–35°C and 8.0, respectively. Initial ammonium concentration was found to have a strong effect on the value of the kinetic parameters of the Michaelis–Menten rate expression at low ammonium levels. However, at high initial concentrations both parameters attained a constant maximum value that is independent of the initial substrate level.
Use of an exchange filtration technique to obtain synchronous sporulation in an extended batch fermentation
Authors: Watson D. C. , Berry D. R.
Published: December 2004

A fermentor system with an external filtration loop has been developed to control the growth and sporulation of yeast in a single vessel. Excess growth medium, instead of being removed by centrifugation, is removed by filtration and replaced with acetate sporulation medium. The technique did give 80% sporulation after 20 hr, greatly improving the rate and degree of synchrony of sporulation and it also eliminated the contamination hazard of the conventional harvest technique, centrifugation, and resuspension of vegetative cells in sporulation medium. Furthermore it permits proper control of the environmental conditions throughout the growth, exchange, and sporulation phase. In this technique 100% recycle of biomass is achieved without any packing of the cells on the filter. This technique has wide application in the study of industrial fermentation that involves microbial differentiation such as the production of ergot alkaloids, bacitracin, and cephalosporin.
Carbon dioxide fixation by immobilized chloroplasts
Authors: Karube Isao , Aizawa Kaoru , Ikeda Sakuji , Suzuki Shuichi
Published: December 2004

Chloroplasts of chinese mustard (Brassica campestris L.) were immobilized in polyacrylamide gel. A 8% polymer concentration was suitable for the immobilization. The activity of the carbon dioxide fixation of immobilized chloroplasts was 65% of that of free chloroplasts. The optimum conditions for the carbon dioxide fixation of immobilized chloroplasts were similar to that of native chloroplasts. However, immobilized chloroplasts were more stable under alkaline conditions and high temperatures than native chloroplasts. Light penetration of the gel was not a limiting parameter of the carbon dioxide fixation. The lifetime of immobilized chloroplasts was three times longer than that of free chloroplasts. 3‐Phosphoglyceraldehyde and other compounds were produced continuously by immobilized chloroplasts.
Penicillin G production by immobilized whole cells of Penicillium chrysogenum
Authors: Morikawa Yasushi , Karube Isao , Suzuki Shuichi
Published: December 2004

Penicillium chrysogenum was immobilized in polyacrylamide gel prepared from 5% acrylamide monomers (85% acrylamide and 15% N,N′‐methylene bisacrylamide). Penicillin produced from glucose by the immobilized mycelium was 17% of that produced by washed mycelium. However, the activity of penicillin production of the washed mycelium decreased with repeated use. On the other hand, the activity of the immobilized mycelium increased initially and decreased gradually with repeated use. The rate of oxygen uptake of the immobilized mycelium was about 30% of that of the washed mycelium. The immobilized mycelium required oxygen for the production of penicillin.
Production of cellulases by Trichoderma reesei QM 9414 in fed‐batch and continuous‐flow culture with cell recycle
Authors: Ghose T. K. , Sahai Vikram
Published: December 2004

The scope in improving enzyme productivities from the cellulose fermentation process is examined in laboratory‐scale fermentors. The maximum productivity (30 IU/liter hr) is attained in a continuous‐culture process with cell recycle using modified medium containing 0.5% cellulose. Optimum dilution rate and recycle ratio are determined as 0.025 hr−1 and 1.2, respectively, for the process. The system is analyzed and steady‐state equations for predicting enzyme protein concentrations in the fermentor are developed. In fed‐batch cultures, slow addition of cellulose at high concentrations can improve enzyme productivity by as much as 33% over a batch process. The scope and results of using modified medium for cellulase production are also presented.
Association of β‐glucosidase with intact cells of Thermoactinomyces
Authors: Hägerdal Bärbel , Harris Harriet , Pye E. Kendall
Published: December 2004

The location of the β‐glucosidase activity in a whole culture broth of the thermophilic organism Thermoactinomyces has been studied. Little β‐glucosidase activity was found in the culture filtrate, while the culture solids contained the major part of the activity of the whole culture broth. The activity does not appear to be adsorbed to the culture solids; rather there is evidence that it is an intracellular soluble enzyme(s). The pH and temperature optima for a crude β‐glucosidase preparation were determined to be pH 6.5 and 50–55°C. Enzyme activity studies indicate that the same enzyme(s) accounts for the β‐glucosidase and the cellobiase activities. The validity of using the filter paper activity of culture filtrates from Thermoactinomyces to predict the total saccharification of cellulosic materials to glucose is discussed.
Light‐induced enzyme system leading to pigmentation
Authors: Kuan K. , Lee Y. Y. , Tebbetts L. , Melius P.
Published: December 2004

α‐Chymotrypsin was light sensitized by acylating with cis‐cinnamoyl ester, a substrate interconvertible to the trans form by ultraviolet (UV) light. The degree of acylation by this method was complete leaving no residual activity of the enzyme. Upon UV irradiation the inhibited enzyme regained about 70% of its original activity, thereby adding light‐sensitiveness to the proteolytic enzyme. In seeking a photographic application of the light‐sensitized enzyme, a pigmenting enzyme was incorporated with it. The coupled enzyme system was shown to exhibit a light signal in the form of dark pigment slurry.
Immobilization of enzymes on activated carbon: Selection and preparation of the carbon support
Authors: Cho Y. K. , Bailey J. E.
Published: December 2004

Based upon its superior catalytic activity for H2O2 decomposition, a bituminous coal‐based activated carbon was selected for investigations of pretreatment and enzyme immobilization methods. Pretreatments considered include acid washing, exposure to strong oxidizing agents, contact with concentrated peroxide solutions, nitration and amination, isothiocyanate derivatization, silanization, and stearic acid coating. Effects of these pretreatments on morphology and trace‐metal content of the carbon pellets have been studied using scanning electron microscopy and dispersive analysis of x rays. Immobilization of glucoamylase by adsorption, glutaraldehyde crosslinking, and covalent attachment to carbon activated by water‐soluble diimide or diazotization have been examined. These different enzyme–carbon catalysts have been characterized by their enzyme loading, enzyme activity, catalytic activity for H2O2 decomposition, or combinations of these measures of performance.
Mathematical model of cell growth and phosphatase biosynthesis in Saccharomyces carlsbergensis under phosphate limitation
Authors: Toda K. , Yabe I.
Published: December 2004

The rate kinetics of growth and acid phosphatase formation in the batch culture of Saccharomyces carlsbergensis LAM 1068 was studied under varying degrees of phosphate limitation. The mathematical model that was developed is concerned with the time lag for exponential growth, the biphasic growth on a substrate (glucose) and its product (ethanol), sustained growth on conservative phosphate, and the derepression of acid phosphatase. The numerical calculations using appropriate parametric constants successfully described the variation in the cell mass, glucose, ethanol, and inorganic phosphate concentrations, and the enzyme activity of acid phosphatase during aerobic growth of S. carlsbergensis under five different conditions of phosphate starvation. A simulation study revealed that the optimum initial phosphate concentration in the medium giving a high productivity of acid phosphate was 2.0 mg phosphorus/g glucose liter.
Solid‐substrate fermentation of alfalfa for enhanced protein recovery
Authors: Bajracharya Rupak , Mudgett Richard E.
Published: December 2004

Solid‐substrate fermentations for extraction of protein from pressed alfalfa residues with Aspergillus sp. QM 9994 aspergillus niger QM 877, and Rhizopus nigricans QM 387 were conducted in shake flasks. Upon reimbibing and second pressing, total protein recovery from alfalfa was increased from 47.2% for control samples and up to 64.5% for fermented samples. Analysis of juice from fermented samples indicated the presence of cellulase as well as pectinase activities. Dialysis cultures of cellulase‐producing fungi showed that total biomass production and solids consumption were much higher than those of a mutant strain lacking the ability to produce cellulase, indicating significant utilization of cellulosic materials in alfalfa. The biomass yields in the former case ranged from 39–47% based on total solids consumption. Since some of the cellulosic and other carbohydrate constituents in alfalfa may be converted into fungal protein, final alfalfa residues following protein extraction in a commercial process would be less bulky for storage and handing and would be more digestible as a nonruminant animal feed.
Utilization of mass–energy balance regularities in the analysis of continuous‐culture data
Authors: Erickson L. E. , Minkevich I. G. , Eroshin V. K.
Published: December 2004

Material and energy balances for continuous‐culture processes are described based on the facts that the heat of reaction per electron transferred to oxygen for a wide variety of organic molecules, the number of available electrons per carbon atom in biomass, and the weight fraction carbon in biomass are relatively constant. Energy requirements for growth and maintenance are investigated and related to the biomass energetic yield. The consistency of experimental data is examined using material and energy balances and the regularities identified above. When extracellular products are absent, the consistency of yield models containing separate terms for growth and maintenance may be investigated using organic substrate consumption, biomass production, oxygen consumption (or heat evolution), and carbon dioxide evolution rate data for a series of dilution rates. The consistency of continuous‐culture data in the published literature is examined.
Removal of diacetyl from beer by adsorbants and diacetyl reductase
Authors: Gupta K. G. , Jain A. K. , Dhawan Surinder
Published: December 2004

Removal of diacetyl from beer with adsorbants like cellulose, silica gel, activated charcoal, calcium phosphate gel, anion‐ and cation‐exchange resins, and silicylic acid black soil bed (SABSB) was attempted in comparison with the enzyme diacetyl reductase (EC 1.1.1.5). Diacetyl could be removed from beer by the adsorbants but they had undesirable effect on the beer quality such as color, pH, and alcohol levels. These adverse effects were not observed with the use of diacetyl reductase. The results favor the enzymatic removal of diacetyl from beer as a superior approach.
Large‐scale isolation of equine liver alcohol dehydrogenase on a blue agarose gel
Authors: Roy S. K. , Nishikawa A. H.
Published: December 2004

Equine liver alcohol dehydrogenase (EC 1.1.1.1) has been purified by a new scheme using a blue agarose gel (Blue Sepharose) as an affinity sorbent. Starting amounts of 0.6 to 10 kg liver have been processed to enzyme possessing 1.5 U/mg average specific activity, in about three to four days. Some parameters concerning adsorption of enzyme to the blue gel as well as recovery therefrom have been explored.
Assimilation efficiency and energy contents of prototrophic bacteria
Authors: Ho K. P. , Payne W. J.
Published: December 2004

When the assimilation efficiency in batch culture of a variety of heterotrophic bacteria was tested in media containing progressively smaller concentrations of carbon substrate, two groups emerged. Those in the first group assimilated carbon progressively more efficiently as the initial concentration in the culture medium was lowered below 2 mg C/ml; some displaying efficiencies exceeding 80%. Those in the second group assimilated carbon at rates that changed little, if at all, with changes in the initial concentrations of carbon substrate. Members of the second group differed from the first in their metabolic versatility as evidenced by the ability of each to catabolize hydrocarbons. The energy content (heat of combustion) of the cells of the species tested varied little with changes in cultured conditions, and values for all fell close to the average for bacteria (5411 cal/g ash‐free dry wt). In continuous aerobic culture on glucose‐minimal medium, the carbon assimilation and energy assimilation efficiencies were simultaneously maximal for Enterobacter aerogenes when the input carbon concentration was 0.2004 mg/ml and the dilution rate was 0.57. An equation for predicting heat of combustion of cells from knowledge of their C,H,N, and O ratios was devised and tested. Precision ranged from +6% to −16%.
Maximization of Candida utilis cytochromes by pulse additions of ethanol to continuous cultures
Authors: Cail R. , Rickard P. A. D. , Rogers P. L.
Published: December 2004

Candida utilis was grown with glucose as growth‐limiting carbon source in batch culture, steady‐state continuous culture, and non‐steady‐state continuous culture. High cytochrome concentrations were routinely recorded in cells harvested in the latter stages of batch culture. They were occasionally recorded in cells from imprecisely controlled steady‐state cultures, but precise control of the steady‐state dissolved oxygen tension stabilized the cytochromes at relatively low levels. Controlled non‐steady‐state continuous cultures, imposed by pulse additions of ethanol, routinely produced cells with high cytochrome concentrations. A mechanism is proposed whereby maintenance of cytochrome derepression in continuous culture is dependent upon indefinitely prolonging an “overshoot” response in gene expression.
Enzyme immobilization by radiation‐induced polymerization of 2‐hydroxyethyl methacrylate at low temperatures
Authors: Kaetsu Isao , Kumakura Minoru , Yoshida Masaru
Published: December 2004

Enzyme immobilization by radiation‐induced polymerization of hydrophilic glass forming monomers, such as 2‐hydroxyethyl methacrylate, was studied. Enzyme radiation damage could be sufficiently retarded at low temperatures. The immobilized enzyme activity yield was markedly higher at low temperature than at higher temperature polymerization. At low temperatures the polymerized composite had a porous structure owing to ice crystallization which depends on the monomer concentration. It was deduced that the enzyme was partially trapped on the polymer surface, partially isolated in the pore, and partially occluded inside the polymer matrix. A decrease in activity caused by enzyme leakage was observed with repeated use in enzyme reactions where the composites had a large porosity. The activity yield showed a maximum at certain optimum porosities, i.e., at optimum monomer concentrations. Continuous enzyme reaction was preferably carried out using immobilized enzyme columns.
Continuous production of NADP by immobilized Brevibacterium ammoniagenes cells
Authors: Murata Kousaku , Kato Jyoji , Chibata Ichiro
Published: December 2004

Whole cells of Brevibacterium ammoniagenes IAM 1645 having the polyphosphate NAD‐kinase were successfully immobilized in a polyacrylamide gel lattice. The immobilized cells were activated by treatment with organic solvents or detergents. The pH optimum of the immobilized cells for the production of NADP was 7.0, and divalent metal ions were required to maintain the elevated activity of polyphosphate NAD‐kinase. Highly pure NADP was continuously produced in high yield by the immobilized cell column. The half‐life of this column was about eight days.
Fractionation of the proteolytic and amylolytic complex enzyme system of Streptomyces aureofaciens and some properties of fractions
Authors: Laluce Cecilia , Molinari Rubens
Published: December 2004

The Streptomyces aureofaciens extracellular proteolytic system was split into four fractions by carboxymethylcellulose (CMC) column chromatography giving three purely caseinolytic fractions and one fraction active toward both starch and casein. The first caseinolytic and amylolytic fraction was further fractionated by DEAE‐Sephadex A‐50 chromatography into one purely amylolytic fraction and another showing both activities, was refractioned into four new fractions by DEAE‐cellulose chromatography. These fractions were found to be heterogeneous by polyacrylamide gel electrophoresis, three of them acted on both starch and casein and a fourth was only caseinolytic. The second CMC fraction was further purified by CMC rechromatography to an homogeneous fraction that hydrolyzes carboxypeptidase A(EC 3.4.2.1) synthetic substrates and solubilizes elastin. It had only one polypeptide chain with a molecular weight of about 28000 daltons, a high thermal stability in the presence of calcium ions, a pH optimum of about 6.8, and a maximal caseinolytic activity at about 50°C.
Characterization of hydrocarbon emulsification and solubilization occurring during the growth of Endomycopsis lipolytica on hydrocarbons
Authors: Roy P. K. , Singh H. D. , Bhagat S. D. , Baruah J. N.
Published: December 2004

A comparative characterization of the phenomena of hydrocarbon emulsification and solubilization taking place during the growth of Endomycopsis lipolytica on n‐alkanes and alkenes was made. Evidence was obtained for the cellular production of different factors involved in emulsification and solubilization of hydrocarbons. It was shown that the production of these factors closely followed cell growth. The inducible nature of the alkane solubilizing factor was demonstrated using actidione as inhibitor. Whereas emulsifying factor was demonstrated using actidione as inhibitor. Whereas emulsifying factors showed a broad affinity to some particular hydrocarbons, solubilizing factor was found to be highly specific for the particular hydrocarbon on which the cells were grown. The emulsifying factor was heat stable whereas the solubilizing factor was highly unstable even at −4°C. Metal‐ion chelating agents strongly inhibited the activity of both of the factors. A crude isolate of the alkane emulsifying factor was obtained and its peptide characteristics were demonstrated. Using EDTA as an inhibitor for the emulsification–solubilization activity, evidence was obtained for the predominent role played by the emulsification–solubilization mechanism in the uptake of alkane by yeast cells.
Lipase synthesis in hydrocarbon fermentation
Authors: Kosaric N. , Zajic J. E. , Aboue G. , Jack T. , Gerson D.
Published: December 2004

A Study was undertaken to establish conditions and relationships for the production of lipases during hydrocarbon fermentation. A culture of Candida lipolytica was isolated by a kerosene enrichment technique from oil‐soaked soil and this microbe was used to study the production of lipase on a kerosene–mineral salts medium. The optimum pH, medium, and temperature for lipase synthesis were established and the properties of the isolated enzyme in terms of its activity and lipid specificity were studied.
Production of Candida utilis protein from peat extracts
Authors: Quierzy P. , Therien N. , Leduy A.
Published: December 2004

Sphagnum peat extracts or hydrolysates have been obtained and used as a culture medium for the production of Candida utilis biomass as single cell proteins. Acid hydrolysis of ground peat (4–60 mesh) in an autoclave operated under a set of conditions for acid strength (0.3‐1.5 (v/v) H2SO4), holding time (1–4 hr), temperature (100–165°C), and weight ratio of dry peat to solution (3.3–16.7 g dry peat/100 g solution) yielded carbohydrate‐rich extracts of different concentrations (1–34g/liter). The best yield (mg total carbohydrate/g dry peat) was obtained for a holding time of I hr and a temperature of 152°C. Low peat concentratio (4.1 g dry peat/100 g solution)resulted in high yield(280mg total carbohydrate/gdry peat) with a corresponding low carbohydrate content in hydrolysate (13 g/liter), while a lower yield with a higher carbohydrate content (34 g/liter)in hydrolysate were found when increasing peat concentration (16.7 g dry peat/100 g solution). Shake‐fladk experiments using peat hydrolysates as the culture medium together with NH4OH (∼4.8 g/liter) and K2HPO4(5 g/liter) as nitrogen and phosphate supplement, respectively, gave a maximum biomass concentration of 7.5 g/liter after 60 hr at 30°C and 200rpm. Batch cultivation in a fermentor under controlled conditions for aeration (4.2 liter/min), agitation (500rpm), temperature (30°C), and pH (5.0) produced a maximum biomass of 10 g/liter after 20 hr with a specific growth rate of 0.13 hr−1. For the continuous cultivation, a maximal biomass productivity of 1.24 g/gliter‐he was obtained at a dilution rate of 0.125 hr −1. Monod's equation's equation has been used for the estimation of the coefficients μMax, Ks, and Y. It was found that the yield coefficient Y is not constant during the progress of batch cultivation.
Continuous‐flow monitoring of lactose concentration
Authors: Volesky B. , Emond C.
Published: December 2004

A specific continuous‐flow analytical system for determination of lactose concentration in a liquid mixture of constituent sugars was developed and tested based on a series of enzymatic reactions. Lactose and glucose oxidase immobilized on a phenol–formaldehyde resin were employed. More detailed study was carried out based on a reaction by‐product quantitatively detected by an available iodide electrode. A multichannel proportioning pump fed two independently operated analytical streams eliminating thus the background glucose interference. With a goal of lactose concentration control in a fermentation process, the system response time delay was shortened to approximately 15 min. Apart from optimization of the analytical system operating parameters, the study indicates also the major application problem areas: lactase inhibition by galactose, galactose oxidation by glucose oxidase, and a partial loss of glucose oxidase activity in a prolonged continuous‐flow operation. A manual Colorimetric Procedure was employed to verify the results of the potentiometric method.
Use of continuous‐culture techniques for determining the growth kinetics of a celluloytic Thermoactinomyces sp.
Authors: Lee S. Edward , Humphrey Arthur E.
Published: December 2004

In order to better understand the kinetics of cellulose degradation by Thermoactinomyces sp., continuous‐culture experiments were performed utilizing the various intermediates of cellulose degradation as the feed substrates. Steady‐state data from the glucose runs suggest that this organism has a growth yield of 0.42 g cell/g glucose, and a specific maintenance of 0.24 g glucose/g cell/hr. The Monod equation did not seen to model the growth well, since a plot of 1/D vs. 1/S gave a maximum specific growth rate that was even lower than one of the steady‐state dilution rates. A dynamic washout experiment suggested a maximum specific specific growth rate of 0.36 hr−1 and indicated that glucose is only slightly growth inhibitory as the inhibition constant, Ki, is 19 g glucose/liter. An equation for substrate concentration for washout conditions was derived. This equation predicted the transient glucose concentration relatively well. A fill‐and‐draw technique was investigated for determination of the growth parameters. It was not successful because of difficulties in contamination and accurately monitoring the dissolved oxygen in the small highly agitated vessel. However, the technique could be useful in studying the growth characteristics of sludge in a waste treatment system where contamination is not a worry. One could cover the medium surface and use a nonsterilizable dissolved oxygen probe of high sensitivity membrane to overcome these difficulties.
Application of a bioluminescence ATP assay in brewery wastewater treatment studies
Authors: Hysert D. W. , Knudsen F. B. , Morrison N. M. , van Gheluwe G. , Lom T.
Published: December 2004

The importance of having a rapid method for determining the viable biomass in activated‐sludge wastewater treatment plants (WWTP) for process control and development is well recognized. The firefly bioluminescence ATP assay has been proposed for this purpose. Such an assay using partially purified firefly luciferase and synthetic firefly luciferin for the bioluminescence reaction, a liquid scintillation counter in the out‐of‐coincidence mode as luminescence detector, and a sludge ATP extraction technique involving dimethyl sulfoxide at room temperature is described. Experiments with several pure bacteria cultures were done to demonstrate the feasibility of applying this assay to activated sludge to activated sludge WWTP investigation and control. The ATP content of samples taken from various points in a 350000 gal/day brewery activated‐sludge WWTP was monitored for 4.5 months. Good linear correlation between ATP and mixed‐liquor suspended solids, return sludge suspended solids, and effluent suspended solids were observed. Percentage viabilities of the various sludge samples were derived from the ATP results.
Urease bound to chitin with glutaraldehyde
Authors: Iyengar Leela , Rao A. V. S. Prabhakara
Published: December 2004

The enzyme (urease amidohydrolase, EC 3.5.1.5) prepared from Cajanus indicus, has been immobilized with glutaraldehyde‐treated chitin as the solid support. The immobilized enzyme was characterized by determining the pH profiles and optimum temperature. Effect of glutaraldehyde concentration on the binding of enzyme to chitin was studied. The storage stability of the chitin–urease system was determined.
Proteolytic denaturation and methods of improving the stability of glucose isomerase preparations
Authors: Adler David , Lim Henry , Cottle David , Emery Alden
Published: December 2004

Evidence is provided in support of proteolytic denaturation of free and immobilized preparations of glucose isomerase from a Bacillus species. A number of methods to improve the stability with respect to proteolysis have been tested and their advantages as well as shortcomings are discussed. These methods include hollow‐fiber treatment, gel permeation, thermal treatment, and addition of protease inhibitors. The half‐life of the free and the cellulose acetate fiber‐entrapped preparations of glucose isomerase can be significantly improved. For example, the hollow‐fiber treatment can improve the half‐life by an order of magnitude.
Properties of penicillin amidase immobilized by copolymerization with acrylamide
Authors: Szewczuk Apolinary , Ziomek Edmund , Mordarski Marian , Siewiński Maciej , Wieczorek Jadwiga
Published: December 2004

An enzyme preparation in a spherical granule form was obtained by copolymerization of penicillin amidase (EC 3.5.1.11) (previously modified with maleic anhydride) and acrylamide via a crosslinking agent. As compared with the native enyme, immobilized amidase is more resistant to heating, has a lower affinity to benzylpenicillin, and is less inhibited by phenylacetate. Its substrate specificity and optimum pH remain unchanged.