bluuebunny/crossref_metadata_2025 huggingface dataset:
Emulsification and degradation of “Bunker C” fuel oil by microorganisms
Authors: Zajic J. E. , Supplisson B.
Published: December 2004

An enrichment culture procedure has been used to isolate mixed culture systems which grow upon “Bunker C” fuel oil. When inoculated into a mineral salts aqueous medium containing Bunker C oil, the mixed cultures initiate oil emulsification. Emulsification usually is observed in 24–48 hr. The role of microbes in this emulsification will be discussed. It appears that certain metabolic products produced by the microbe possess properties of surfactants. Bacteria and fungi have been isolated which possess the ability to cause emulsification. Freeze‐dried biomass is also capable of emulsifying oil. Chromatographic analyses of biodegraded Bunker C fuel oil show that microorganisms selectively metabolize the n‐paraffin fraction.
Growth models of cultures with two liquid phases. VI. Parameter estimation and statistical analysis
Authors: Shah P. S. , Erickson L. E. , Fan L. T. , Prokop A.
Published: December 2004

Parameter estimation studies have been conducted employing mathematical models developed previously by the investigators and experimental data collected by the last author. A batch fermentation process in which Candida lipolytica were cultured on n‐hexadecane dissolved in dewaxed gas oil was employed to obtain the experimental data. The kinetic data from a number of batch experiments conducted at different initial substrate concentrations and different dispersed phase volume fractions were analyzed assuming that, the basic model parameters (maximum specific growth rate, saturation constant, substrate phase equilibrium constant, adsorption constant, desorption constant, etc.) did not change from experiment to experiment. The Gauss‐Newton method with modification by Greenstadt, Eisenpress, Bard, and Carroll was used to minimize the conventional sum of squares criterion on the IBM 300/50 computer. The individual confidence intervals were obtained for each individual parameter. Tin‐ models were compared employing the F‐test for equality of variances and an analysis of residuals. For the two best models, the estimated parameter values were compared with available experimental information. The results showed good agreement between the experimental data and the values predicted by the mathematical models. The results presented in this work did suggest that growth on small segregated drops may be more important than continuous phase growth on dissolved substrate.
Diffusion influences in denaturable insolubilized enzyme catalysis
Authors: Ollis David F.
Published: December 2004

The influence of diffusion on the apparent thermal stability of a reversibly or irreversibly denaturable enzyme is examined theoretically when he enzyme is uniformly distributed in a porous solid. If the overall reaction rate is influenced by diffusion through the catalyst, the insolubilized catalyst is shown to yield an apparently more thermally stable enzyme even though the maximal velocity Vm, and the Michaelis constant, Km, are the same for the free and insolubilized forms of enzyme.

Brief consideration is given to the experimental conditions needed to clearly demonstrate whether insolubilization does or does not effect the thermal stability of the enzyme.
Conversion of benzylpenicillin to 6‐aminopenicillanic acid in a batch reactor and continuous feed stirred tank reactor using immobilized penicillin amidase
Authors: Warburton D. , Dunnill P. , Lilly M. D.
Published: December 2004

A rate equation has been derived to describe the hydrolysis of benzylpenicillin to 6‐aminopenicillanic acid by penicillin amidase. The integrated from of the rate equation has been shown to predict satisfactorily the progress of the reaction in a batch reactor using either soluble or immobilized penicillin amidase. The rate equation was also used to predict the performance of a continuous feed stirred tank reactor containing immobilized enzyme. There was good agreement with experimental measurements.
Oxygen transfer into mycelial pellets
Authors: Kobayashi Takeshi , Van Dedem G. , Mooyoung M.
Published: December 2004

The oxygen uptake rate in mycelial pellets of Aspergillus niger was studied experimentally and theoretically. The specific rate of respiration of mycelial pellets was found to decrease significantly with increasing pellet size. The distribution of respiratory activity in the mycelial pellets was evaluated and the specific rate of respiration of disrupted mycelia showed adaptation to the concentration of oxygen in the medium. The decrease of the specific rate of respiration of the mycelial pellets could be estimated according to diameter, mycelial density, oxygen diffusivity, and adaptation to the concentration of oxygen. Good agreement was found between the theoretical analysis and the experimental data.
Fed‐batch hydrocarbon fermentation with colloidal emulsion feed
Authors: Yoshida Fumitake , Yamane Tsuneo , Nakamoto Ken‐Ichiro
Published: December 2004

Candida tropicalis was cultured with n‐hexadecane, dispersed in water as submicron droplets, as the only carbon substrate; the emulsion being fed continuously into a fermentor containing only an aqueous medium (fed‐batch culture). The results have demonstrated that the organism takes up hydrocarbon accommodated in the aqueous phase as submicron droplets. The cell/substrate yield for the linear growth phase, where growth was limited by the supply of the substrate, was much higher than the yield for the exponential growth phase.
Preparation of immobilized invertase
Authors: Maeda Hidekatsu , Suzuki Hideo , Sakimae Akihiro
Published: December 2004

Immobilized invertase was prepared by ionically binding the enzyme to diethylaminoacetyl cellulose (DEAA‐cellulose). DEAA‐cellulose‐invertase complex was quite stable to electrolyte in the range of pH 5–7. Bound invertase was less active than the native enzyme, and approximately 55–70% of the enzyme activity was lost on binding. The complex was stable for 9 days' continuous inversion in a column system at 30°C, but was rather unstable at 40°C. Heat stability and the effect of temperature on the reaction rate of the complex were almost identical with those of the native enzyme.
Experimental and mathematical modeling studies of protozoan predation on bacteria
Authors: Canale R. P. , Lustig T. D. , Kehrberger P. M. , Salo J. E.
Published: December 2004

The predation of bacteria by protozoan in both continuous and batch cultures was studied using experimental and modeling techniques. The predator organism was the ciliate, Tetrahymena pyriformis. The bacterium, Aerobacter aerogenes, served as the prey. Several batch growth responses were observed each initiated at a different nutrient level. Continuous cultures were conducted over a range of dilution rates. The models studied were partially successful in simulating the empirical data. Deviations between the model and the actual population behavior are discussed and possible explanations for the differences proposed.
Effects of polymer additives on fermentation parameters in a culture ofA. niger
Authors: Elmayergi H. , Scharer J. M. , Moo‐Young M.
Published: December 2004

Of 24 different polymer and surfactant materials examined, a carboxypolymethylene (“Carbopol”) was found to cause enhancement of respiration rates in anAspergillus nigerculture by as much as 200%. Enhancement of other fermentation parameters, such as cellular growth and amylase production, was also observed.

The enhancement effects of Carbopol were examined with clusters of spores and mold pellets. In the first case, it appears that the ionized carboxyl groups of Carbopol induced electrostatic repulsion among the spores thus initiating pulp growth with increased interfacial area of contact between the mold and the nutrient medium. In the second case, the Carbopol additive formed a thin film attached to the surface of the pellets which seemed to be responsible for an increased rate of potassium transport and, hence, fermentation yields. Additive utilization as substrate and physiological changes in the culture were not observed in these cases.

It was also found that the probability of pellet formation, the size of pellets formed, and the number of spores per pellet can be correlated to the energy input to the fermentation system.
Mixed culture biooxidation of phenol. I. Determination of kinetic parameters
Authors: Pawlowsky U. , Howell J. A.
Published: December 2004

A mixed culture derived from soil and activated sludge organisms was used to degrade phenol which was inhibitory to microorganisms at higher concentrations. The purpose of the experiments was to determine the kinetic parameters governing growth of the organisms by measuring growth rates in batch culture. To maintain a constant inoculum for the experiments inoculum was taken from a continuously operating continuous culture. Two populations were studied corresponding to two separate residence times in the continuous culture apparatus. One contained predominantly filamentous organisms, the other nonfilamentous. Five kinetic models were applied to the data and the best kinetic parameters for each model were determined by nonlinear least squares techniques. The models were then evaluated for best relative fit to the data. No significant differences were found between the models on the basis of fit and so a choice was made on the grounds of simplicity. A model proposed by Haldane was chosen as the best. No function however gave a satisfactory fit at the highest growth rates obtained. This experimental maximum in the plot of growth rate against substrate concentration was very sharp.
Thermal stability of glucose oxidase and its admixtures with synthetic polymers
Authors: O'malley James J. , Ulmer Robert W.
Published: December 2004

The thermal stability of glucose oxidase in solution was studied as a function of time and temperature between 37–60°C. As expected, the rate of thermal inactivation increased with temperature and at 60°C more than 80% of the enzyme's activity was lost after 0.5 hr incubation. Similar stability measurements on enzyme solutions containing water soluble synthetic polymers showed that several of the polymers significantly enhanced the thermal stability of glucose oxidase. Copolymers of vinyl acetate with either vinyl pyrrolidone or vinyl alcohol were found to be particularly effective. The molecular weight of the added polymers was found to be unimportant in the stabilization process but both polymer concentration and compositions were shown to be critical parameters.
Growth yields of microorganisms on methanol and methane. A theoretical study
Authors: Van Dijken J. P. , Harder W.
Published: December 2004

An attempt was made to calculate growth yields of microorganisms on methanol and methane on the basis of known biochemical pathways of C1 metabolism. Since 3‐phosphoglycerate is a key intermediate in the assimilation pathways of C1 compounds, the calculations were based on the assumption that the synthesis of cell material from C1 substrates can be regarded as a two step process. When YATP on 3‐phosphoglycerate was taken as 10.5, a maximal cell yield of organisms of the composition C4H8O2N on methanol was found to be 0.73 g cells/g substrate. For growth on methane a value of 0.91 g cells/g substrate was calculated when a mixed function oxidase was implicated in methane oxidation. These yields were calculated on the basis of the ribulose phosphate pathway of formaldehyde fixation as the major pathway of C1 assimilation. Yields calculated on the basis of the serine pathway were on an average 20% lower. The calculations disclosed that for growth on methane, at least for Methylococcus capsulatus, a reversed electron transport system is required when methane is oxidized by a mixed function oxidase. The theoretical cell yields on methanol and methane have been compared with experimentally obtained yields and the validity of the estimations of growth yields on the basis of the present calculations is discussed.
Enzymatic breakdown of water insoluble substrates
Authors: Suga K. , Van Dedem G. , Moo‐Young M.
Published: December 2004

The kinetic behavior of the enzymatic breakdown of crosslinked dextran (Sephadex) by a dextranase from Penicillium funiculosum was investigated as a model for enzymatic degradation of insoluble materials. A theoretical model is developed for the description of an enzymatic reaction on an insoluble substrate. Experimental data are compared to those predicted by the model which are calculated by using independently determined parameter‐values such as the Michael is constants, effective pore radius of the particles, and the Stokes radius of the enzymes. Fairly good agreement was found between the theoretical analysis and the experimental data.
Fermentation of waste mechanical fibers from a newsprint mill by the rot fungus Sporotrichum pulverulentum
Authors: Eriksson Karl‐Erik , Larsson Kjell
Published: December 2004

The growth and protein production of Sporotrichum pulverulentum, formerly called Chrysosporium lignorum, have been studied in submerged cultures using lignin‐containing waste fibers from a newsprint mill as the only carbon source. The influence of different nitrogen sources on the growth parameters has been particularly investigated. The regulation of the production of extracellular enzymes and their interaction with the fibers is discussed. Experiments with cellulose of different degrees of polymerization and crystallinities showed that the protein content in the residual substance decreased, particularly when the crystallinity increased. When the highly crystalline powder cellulose was used as carbon source, the protein content in the residual substance was only 6% and with the mechanical waste fibers 14%. The results obtained demonstrate that the more complex the carbon source the more difficult it is to digest and the more enzyme has to be produced for its degradation. This puts a heavy burden on the protein synthesizing mechanism. Utilizing results from other work, where the endo‐ and exo‐l, 4‐β‐glucanases produced by S. pulverulentum for the degradation of cellulose have been quantitatively purified, it has been calculated that the extracellular enzymes under these conditions can together account for approximately 30% of the protein in the mycelium. The endo‐ and exo‐1,4‐β‐glucanases account for up to 55% of the extracellular protein.

Certain possibilities of producing a final product with a high protein content using complex carbon sources are also mentioned.
Efficient biokinetic experimental designs
Authors: Johnson David B. , Berthouex Paul M.
Published: December 2004

Of the experimental methods available for obtaining data to estimate the biological kinetic parameters μm,Ks, andYeach requires considerable experimental effort, yet often yields somewhat imprecise estimates of the parameters, particularlyKs. Therefore it would be worthwhile to seek ways to get parameter estimates of greater precision using less experimental effort. The precision of parameter estimates is strongly dependent, upon the settings of the independent, variables used in the experiments. This dependence is explained and an attempt made to show how experimental settings can be determined that lead efficiently to precise parameter estimates with minimal effort.
A model for diauxic growth
Authors: Van Dedem G. , Moo‐Young M.
Published: December 2004

A model is developed to predict batch and continuous culture behavior of fermentations on two different carbon and energy sources. The basic assumption of the model is that the permease for the favored substrate is constitutive, whereas the permease for the second substrate is subject to induction and catabolite repression. Simulations of the model show features of diauxic growth described in the literature.
Kinetic studies of mold α‐galactosidase on PNPG hydrolysis
Authors: Kobayashi Harumi , Suzuki Hideo
Published: December 2004

The kinetic properties of α‐galactosidase of Mortierella vinacea were investigated in detail using PNPG (p‐nitrophenyl‐α‐D‐galactopyranoside) as a substrate. Consequently, the enzyme was markedly inhibited not only by the substrate, but also by the galactose hydrolized. The initial rate of reaction at sufficiently high substrate concentrations, however, did not fall to zero and did approach a finite value. Galactose behaved as a mixed inhibitor and was neither totally competitive nor totally noncompetitive. A rate equation was obtained from a generalized equation derived from a kinetic model which took both the inhibitions into consideration. The constants used in the equation were appropriately estimated. The calculated rate agreed fairly well with the observed initial rate. Moreover, the PNPG hydrolysis progressing in a batch system was found to be approximately representable by simple first order kinetics in which the rate constant was dependent on the initial substrate concentration.
New mechanisms for the biosynthesis and metabolism of 2‐keto‐L‐gulonic acid in bacteria
Authors: Makover S. , Ramsey G. B. , Vane F. M. , Witt C. G. , Wright R. B.
Published: December 2004

L‐Sorbose is oxidized to 2‐keto‐L‐gulonic acid (KGA) via the following sequence of reactions which we call the “sorbosone pathway”: L‐sorbose ⇌ L‐sorbosone → KGA. The first step is reversible and is mediated by enzymes found in a soluble fraction obtained from Pseudomonas putida ATCC 21812. Although no cofactor requirements were found for the forward reaction, the reverse reaction clearly required NADH. Enzymes for this NADH‐dependent synthesis of L‐sorbose could be differentiated on the basis of molecular weights. The second step in the sorbosone pathway is catalyzed by a particulate enzyme found in extracts from P. putida and Gluconobacter melanogenus IFO 3293. The rate limiting reaction in the sorbosone pathway is the synthesis of L‐sorbosone. In addition to P. putida, Klebsiella pneumoniae (ATCC 27858) and Serratia marcescens (ATCC 27857) also contain the enzymes which catalyze the reactions of the sorbosone pathway. Two of the bacteria studied, P. putida and G. melanogenus, also contain an enzyme involved in the further metabolism of KGA to L‐idonic acid. This enzyme, referred to as KGA‐reductase, is found in the soluble fraction of cell‐free extracts and is dependent on NADH or NADPH.
Preparation of immobilized β‐galactosidase by poly(vinylpyrrolidone) and the continuous hydrolysis of lactose in acid whey
Authors: Maeda Hidekatsu
Published: December 2004

Immobilized β‐galactosidase gel was prepared using poly(vinylpyrrolidone) (PVP) under β‐ray irradiation. In contrast to the gelation of N‐vinylpyrrolidone monomer–enzyme solution, the gelation of PVP‐β‐galactosidase solution (PVP content: 10%) was almost completely uneffected by the dose rate and amount of phosphate present. PVP‐enzyme solution was gelled by irradiation with 3.0 Mrad. The expressed activity of the PVP‐enzyme gel was about 30% of the initial activity and added activity was almost totally entrapped. No leakage of enzyme from these gels could be detected. Leakage was, however, detected in the case of the gelation of PVP‐enzyme solution containing more than 1% of enzyme protein. When the general properties of the gel were compared with those of the native enzyme, the gel proved to be slightly inferior to the native enzyme with respect to optimum temperature, heat stability, pH activity, and pH stability. Continuous hydrolysis of lactose in acid whey could be carried out at 50°C using a column packed with the gel and sawdust and the degree of hydrolysis was found to be almost, constant for 12 days. The merits of using PVP in the immobilization of enzymes include the simplicity of the procedure and the fact that the PVP‐enzyme gel can be used in the food industry without anxiety because of its high degree of compatibility with living organisms.
Substrate inhibition kinetics: Phenol degradation by Pseudomonas putida
Authors: Hill Gordon A. , Robinson Campbell W.
Published: December 2004

A pure culture of Pseudoinonas putida was grown in both a batch and continuous culture using phenol as the limiting substrate. Of two substrate inhibition models examined, the Haldane function was found to statistically best describe the kinetics. The applicable kinetic constants were either measured (μM, KI) or estimated (KS) from the experimental data. Particularly in the continuous culture, wall growth was found to exert significant effects on the broth biomass concentration and phenol conversion, both of which decreased with increasing amounts of wall growth. These effects are opposite to those predicted by wall growth models and to experimental results of others using mixed culture (activated sludge) systems.
The preparation and properties of hornblende as a support for immobilized invertase
Authors: Thornton D. , Flynn A. , Johnson D. B. , Ryan P. D.
Published: December 2004

The suitability of hornblende as a support for immobilized β‐fructofuranosidase (invertase) was studied, with regard to the physical stability of the support and the thermal and operational stability of the immobilized enzyme. Hornblende was more stable than Enzacryl‐Alo or Enzacryl‐TIO, and marginally more stable than porous glass. Invertase immobilized on hornblende was more stable during long‐term operation than invertase immobilized on porous glass. An active preparation of immobilized invertase was obtained also on pyroxene particles.
Variable‐volume continuous cultivation
Authors: Dunn I. J. , Mor J.‐R
Published: December 2004

Equations are developed which describe variable‐volume cultivations, including fed‐batch systems. An analogy is drawn between the quasi‐steady state in variable‐volume cultivation and a dynamic steady state in variable‐flow, constant‐volume chemostat bioreactors. Switching procedures are developed to give a steady‐state transition from batch to fed‐batch and to continuous operation. In this respect, considerations in the literature have been extended. Computer solutions of the governing differential equations verify the theory and provide insight into the behavior of variable‐volume stirred tank reactors.

Application of variable‐volume cultivation as a tool in investigating growth rates at low substrate levels is suggested. Variable‐volume bioreactor systems could be also to obtain controlled dynamic conditions for research or production purposes.
Macrokinetics and operational stability of immobilized glucose oxidase and catalase
Authors: Buchholz K. , Gödelmann B.
Published: December 2004

Glucose oxidation by immobilized glucose oxidase (GlO) and catalase (Cat) has been investigated in batch and continuous reactions for operational studies. The macrokinetics of the process depend on coupled reaction steps and diffusion rates. The problem may be approximated by a simple pseudohomogeneous model taking into account both substrates of glucose oxidase and the intermediate reaction product H2O2. The effectiveness of both enzymes is enhanced in the coupled reaction path, the overall effectiveness nevertheless is very low. H2O2 causes the inactivation of both GlO and Cat. The rates of deactivation depend on the oxidation rates of glucose that give different quasistationary levels of H2O2 concentration. As a first approximation, the deactivation rates may be described by first‐order reactions with respect to H2O2.
Application of mass and energy balance regularities to product formation
Authors: Erickson L. E. , Selga S. E. , Viesturs U. E.
Published: December 2004

Material and energy balances for fermentation processes with product formation are developed using regularities which are frequently useful in analyzing experimental results. Available electron balances are presented and used to analyze the results of experiments in which biomass and lysine are produced in batch culture using molasses and corn extract as organic substrates. Measured values of biomass productivity, lysine productivity, O2 consumption rate, heat evolution rate, CO2 evolution rate, and rate of utilization of reducing sugars (RS) are used to obtain estimates of biomass energetic yield, lysine energetic yield, and fraction of substrate energy evolved as heat. For two of the three experiments, based on the entire fermentation, the measured mass rate variables are very consistent and energy measurement errors are less than 10% when proper consideration is given to both the RS and the amino acids present in the organic substrate. The average measured value of 26.5 kcal/equivalent (equiv) of available electrons transferred to oxygen compares favorably with the known average value of 27 kcal/equiv.
Immobilization of enzymes on activated carbon: Properties of immobilized glucoamylase, glucose oxidase, and gluconolactonase
Authors: Cho Y. K. , Bailey J. E.
Published: December 2004

Apparent kinetics and pH–activity relationships have been determined for glucoamylase and glucose oxidase immobilized on activated carbon using a diimide method. Reaction rate expressions of Michaelis–Menten form adequately approximate the observed kinetics for both enzyme preparations over the ranges of substrate concentrations considered. Influences of external mass transfer as well as substrate and product adsorption on interpretation of the experimental data have been examined. Immobilization of a glucose oxidase–gluconolactonase enzyme mixture has been found to increase substantially the ratio of gluconolactonase to glucose oxidase activities compared to the corresponding activity ratio for these enzymes in solution.
Photocontrol of affinity chromatography: Purification of asparaginase by photosensitive AHA‐gel
Authors: Karube Isao , Ishimori Yoshio , Suzuki Shuichi , Sato Toshio
Published: December 2004

An agarose gel modified with N‐(ω‐aminohexytl)‐L‐aspartic acid (AHA) and spiropyran compound (AHA–spiropyran gel) was prepared and the photocontrolled binding and releasing of asparaginase were investigated with the AHA–spiropyran gel. Asparaginase was bound on the AHA–spiropyran gel under visible light and was released in the dark. The optimum conditions for photocontrolled binding and releasing of asparaginase were a 0.05M phosphate buffer concentration and pH 7.0. Seventy‐five percent of the bound asparaginase was released from the AHA–spiropyran gel column in the dark. Ninetyfold purification of asparaginase was performed with the AHA–spiropyran gel Column.
Parameter evaluation and performance studies in a fluidized‐bed immobilized enzyme reactor
Authors: Emery A. N. , Cardoso J. P.
Published: December 2004

Dispersion and mass‐transfer characteristics and fluidization parameters influencing the performance of a small pilot‐plant immobilized enzyme reactor are evaluated. The suitability of a dispersed plug‐flow model to predict the conversions obtained in the enzymatic reaction (starch → glucose) catalyzed by amyloglucosidase immobilized to solid and porous carriers is assessed. The performance of a fluidized‐bed reactor is compared on the basis of a normalized residence time with that of a fixed bed and found to be superior.
Effect of diffusion limitations and floc size distributions on fermentor performance and the interpretation of experimental data
Authors: Atkinson B. , Rahman F.‐Ur‐
Published: December 2004

The biological rate equation that describes the overall rate of substrate uptake by microbial films has been extended to microbial flocs with the aid of a shape parameter. The “solid”‐ and liquid‐phase diffusion limitations are explored and found to depend largely on a dimensionles characteristic size k21Vp/Ap. Procedures are discussed by which k21Vp/Ap can be determined from experimental data on the conversion efficiency in a completely mixed fermentor and measurements carried out on flocs recovered from the fermentor are assessed. Floc size distributions are shown to affect the performance characteristics of a fermentor when some of the flocs are sufficiently large to exhibit a diffusional limitation, and it is concluded that a single mean floc size (k21Vp/Ap)* is sufficient to characterize a given distribution, at least when all the flocs are geometrically similar. The mean floc size closely corresponds to the “surface” mean floc size of the floc size distributions.
Pulp and paper mill solid wastes as substrates for single‐cell protein production
Authors: Pamment N. , Robinson C. W. , Moo‐Young M.
Published: December 2004

We have investigated the upgrading of some typical pulp and paper mill solid wastes into protein‐enriched animal feed using the cellulolytic fungus Chaetomium cellulolyticum. The waste residues used were six different primary clarifier sludges and a sample of tertiary centricleaner rejects. These were obtained from mills whose modes of operation spanned the range typically in present‐day usage: groundwood, sulfite, semichemical, Kraft, and thermomechanical pulping, with and without bleaching. Crude protein production from the solid waste residues is compared to that obtainable from fermentation of untreated or caustic‐pretreated sawdusts. Some of these waste residues, especially the Kraft pulp mill rejects, appear to be promising sources of substrate for single‐cell protein production. In these preliminary findings, up to 28% dry weight crude protein content of the product has been obtained at specific growth rates of up to 0.12hr−1 on direct utilization of the wastes.
Bioprobe electrode for phenol
Authors: Neujahr Halina Y. , Kjellén Karin G.
Published: December 2004

A clark oxygen electrode is coated with a thin layer of cell paste of induced trichosporon cutaneum. This bioprode enables one to perform rapid, quantitative determination of phenol in the 0–15 mg/liter range. The assay uses only 2–5 ml and is complete 15 sec after adding the sample. The bioprobe is stable for at least five days at room temperature. It lasts at least 100 assays. Induced yeast cells come from shake cultures or agar plates. They can be freeze‐stored for several weeks before mounting on the electrode. A method of estimating corrections for other exidizable substances is exemplified. The bioprobe can be used to measure phenol in water, fermentation broth, and municipal sewage.
Enzyme immobilization by radiation‐induced polymerization of hydrophobic glass‐forming monomers at low temperatures
Authors: Kaetsu Isao , Kumakura Minoru , Yoshida Masaru
Published: December 2004

Enzyme immobilization was studied by means of radiation‐induced polymerization of hydrophobic glass‐forming monomers at low temperatures. The polymerized hydrophobic composite was generally obtained in microspheric form. Enzymatic activity showed little decrease with repeated use in these systems. The particle size of the microsphere increased with increasing monomer concentration, and activity yield had a maximum at an optimum monomer concentration. Immobilization by copolymerization of hydrophilic and hydrophobic comonomers was also investigated and a maximum activity yield was found at a certain monomer concentration. A model scheme for immobilization at low temperatures was proposed and discussed.
Deacylation of benzylpenicillin by immobilized penicillin acylase in a continuous four‐stage stirred‐tank reactor
Authors: Carleysmith S. W. , Lilly M. D.
Published: December 2004

Immobilized penicillin acylase has been used for the deacylation of benzylpenicillin at 37°C in a continuous reactor consisting of four 1 liter stirred tanks connected in series. There was good agreement between the predicted and actual conversions obtained in each tank under steady‐state conditions. The operational stability of the immobilized enzyme in the tanks depended on the pH and the rate of addition and concentration of alkali needed to neutralize the acid produced during the reaction. At pH 7 with the addition of 2M NaOH, the half‐life for enzyme stability was greater than 400 hr in all tanks. This was over half the value for the immobilized enzyme when stored at 37°C and pH 7.
Production and surface‐active properties of microbial surfactants
Authors: Margaritis A. , Zajic J. E. , Gerson D. F.
Published: December 2004

A new source of surface‐active compounds produced by microbes was investigated. These biologically derived surfactants (biosurfactants) were found to be extracellular products of two newly isolated Corynebacterium species, which were gorwn on kerosene (Imperial Oil No.9). Batch‐growth kinetic studies were carried out in a 14 liter fermentor and the production of biosurfactants was found to be cell growth associated. The surface tension of the whole microbial broth was reduced to a minimum of about 30 dyn/cm, as compared with the surface tension for distilled water of 72 dyn/cm. The crude biosurfactants were recovered from the cell‐free broth, freeze‐dried, redissolved in water, and their surface‐active properties were studied. The biosurfactants reported here were found to be nontoxic and their ability to lower the surface tension of water was found to be comparable to that of sodium dodecylbenzene sulfonate, common commercial synthetic surfactant.
Algal single cell protein from wastewater treatment and renovation process
Authors: Moraine R. , Shelef G. , Meydan A. , Levi A.
Published: December 2004

A Source of high‐quality protein for animal feed, based upon algae recovered in the process of upgrading waste oxidation pond effluents and promising to be particularly economical, is being developed at the Technion. Unlike other types of single cell protein(SCP), the algal protein does not have to return the full production cost but only that of concentration and final processing. The balance is shared by the value of waste disposal and the reclaimed water. Whereas such systems as activated sludge require considerable mechanical energy to supply the oxygen needed for aerobically degrading organics in wastewater, oxidation ponds utilize solar energy for that purpose. The sludge obtained when their effluents are clarified consists largely of algae, bacteria, fungi, and zooplankton in relative proportions varying with operating conditions, and contains 40–60%(dry basis) high‐quality protein. The high rate oxidation pond (a particularly intensive type of pond) produces on the average 34 g/m27sol;day solids, or over 100 tons/ha (hectare) annually. Two clarification routes have been found promising: centrifugation and alum flocculation followed by frothflotation. The latter route is less expensive in terms of both fixed and operating cost, and gives clarified effluent of higher quality, which can be seasonally stored with minimal eutrophication because the aluminum removes most of the phosphate from the effluent. A good product has been obtained by drum‐drying the concentrate, and preliminary feeding tests have indicated that it can replace at least 1/4 of the soymeal in broiler rations and 2/3 of the fishmeal in carp feed. No ill effect of the aluminum in the product recovered by alum flocculation has been found so far a process for removing and recycling the aluminum has been developed nonetheless, in case ill effects do show up in further tests. The combined value of the benefits derived from a system centered around the high‐rate oxidation pond with clarification by flocculation–flotation, in terms of waste treatment by alternative means, potable water saved, and soymeal replaced, significantly exceeds estimated cost.
Theoretical and experimental analysis of a soluble enzyme membrane reactor
Authors: Greco Guido , Alfani Francesco , Iorio Gabriele , Cantarella Maria , Formisano Angela , Gianfreda Liliana , Palescandolo Rosaria , Scardi Vincenzo
Published: December 2004

Recently enzyme immobilization techniques have been proposed that are mainly founded on the formation of an enzyme–gel layer onto the active surface of an ultrafiltration membrane within an unstirred ultrafiltration cell. If the membrane molecular‐weight cutoff is less than the enzyme molecular weight and hence such as to completely prevent enzyme permeation (once the enzyme solution has been charged into the test cell and pressure applied to the system), a time progressive increase in enzyme concentration takes place at the upstream membrane surface that can eventually lead to gelation and hence to enzyme immobilization. However, depending on the total enzyme amount fed, the maximum enzyme concentration achieved in the unsteady state could be less than the gelation level. In this situation, no immobilization occurs and the enzyme still remains in the soluble form although it is practically confined within a limited region immediately upstream the membrane and at fairly high concentrations. In this paper, the experimental conditions that allow gelling to occur are discussed together with a theoretical analysis of the soluble enzyme membrane reactor which is obtained when no gelling takes place. Such a system could be usefully employed in performing kinetic analyses at high enzyme concentration levels that are still in the soluble form.
Mass‐transfer effects on the rate of isomerization of D‐glucose into D‐fructose, catalyzed by whole‐cell immobilized glucose isomerase
Authors: Boersma J. G. , Vellenga K. , de Wilt H. G. J. , Joosten G. E. H.
Published: December 2004

The investigated catalyst system consists of immobilized Arthrobacter cells containing the enzyme glucose isomerase, which catalyzes the isomerization of glucose into fructose. The internal structure of the catalyst was determined from electron microscope photographs of replicas of freeze‐etched catalyst. On the basis of the photographs a model for the internal structure of the catalyst was proposed. This structure was subsequently used to describe the reaction including mass‐transfer effects. It appeared that under normal operating conditions the external mass‐transfer rate does not influence the overall rate of reaction. The effect of internal mass‐transfer resistances on the overall reaction rate can well be accounted for by the socalled porous sphere model. The intrinsic kinetics of the isomerization catalyzed by the present catalyst system can be represented by a modified Michaelis–Menten equation for a reversible one‐substrate reaction.
Growth of Spirulina maxima on cow‐manure wastes
Authors: Oron Gideon , Shelef Gedaliah , Levi Anna
Published: December 2004

Experiments were carried out on culturing the blue‐green alga Spirulina maxima on raw cow‐manure wastes in an outdoor pond. Improved growth was obtained at pH above 9.2 and temperature above 32°C, with half the radiation intensity required for other green algal species. A yield of 3 g/liter, in terms of total suspended matter, was achieved. The main advantage of this method is that S. maxima removes nutrients and thus serves as an alternative protein source.
Concentration of baboon endogenous virus in large‐scale production by use of hollow‐fiber ultrafiltration technology
Authors: Weiss S. A.
Published: December 2004

A process is described in which the baboon endogenous virus (BaEV) is produced under optimum conditions in cell culture, and concentrated by hollow‐fiber ultrafiltration technology under conditions of large‐scale production. This system has advantages over conventional systems in that the flow rate is increased 2.5‐fold during concentration. Thermal inactivation of BaEV was retarded by the addition of lactose glutamate to the harvested tissue culture fluid. After concentration, at least 91% of the virus RNA‐directed DNA polymerase is recovered with a concomitant increase in infectious virus. Materials needed for modifying described systems may be obtained from commercial sources.
Mechanism of the enzymatic hydrolysis of cellulose: Effects of major structural features of cellulose on enzymatic hydrolysis
Authors: Fan L. T. , Lee Yong‐Hyun , Beardmore David H.
Published: December 2004

The susceptibility of cellulose to enzymatic hydrolysis is affected by the structural features of cellulosic materials. It has been suggested that the crystallinity and surface area of cellulose fibers are the most important structural features in this regard. This study investigated in depth the relative effects of these two structural features upon the enzymatic hydrolysis of cellulose and the change of the structural parameters of cellulose during the course of hydrolysis. It was found that the hydrolysis rate is mainly dependent upon the fine structural order of cellulose which can best be represented by the crystallinity rather than the simple surface area. Monitoring the changes in the structural parameters during the course of reaction showed that surface area is not a major limiting factor that slows hydrolysis in its late stages as has been suggested. This information concerning structural features is used to elucidate the mode of action of cellulase.
Extraction of hemicellulose from ryegrass straw for the production of glucose isomerase and use of the resulting straw residue for animal feed
Authors: Chen W. P. , Anderson A. W.
Published: December 2004

The hemicellulose fraction of ryegrass straw was extracted with NaOH and used for the production of glucose isomerase by Streptomyces flavogriseus. The level of hemicellulose extracted increased proportionately with increasing NaOH concentration up to about 4%, then the rate of increase slowed down. Hemicellulose extraction was facilitated by the combined application of heat and NaOH. Approximately 15% hemicellulose (12% as pentosan) could be obtained by treating straw with 4% NaOH for either 3 hr at 90°C or 24 hr at room temperature. The highest level (3.04 units/ml culture) of intracellular glucose isomerase was obtained when the organism was grown at 30°C for two days on 2% straw hemicellulose. The organism also produced a high yield of glucose isomerase on xylose or xylan. The NaOH‐treated straw residue, after removal of hemicellulose, had approximately 75% higher digestibility and 20% higher feed efficiency for weanling meadow voles than untreated straw. Thus, the residue could be used as animal feed. A process for the production of glucose isomerase and animal feed from ryegrass straw was also proposed.
Continuous production of bacitracin by immobilized living whole cells of Bacillus sp.
Authors: Morikawa Yasushi , Karube Isao , Suzuki Shuichi
Published: December 2004

Whole cells of Bacillus sp., a bacitracin‐producing bacteria, were immobilized in polyacrylamide gel. The continuous production of bacitracin by an immobilized whole‐cell‐containing air‐bubbled reactor was examined with 0.5% peptone solution. The bacitracin productivity (28 units/ml/hr) obtained with this system was higher than that with a batch system. The effluent bacitracin concentration increased with increasing aeration rate and reached a steady‐state maximum above the aeration rate of 3.0 liter/min. A high bacitracin productivity was retained for at least eight days when the gel was washed with sterilized saline at a flow rate of 250 ml/hr for 2 hr once a day. The half‐life of the immobilized whole‐cell system was about 10 days. Bacitracin productivity by the immobilized whole‐cell reactor was higher than that by a conventional continuous fermentation process at high dilution rates.
Enhancement of cellulose accessibility and enzymatic hydrolysis by simultaneous wet milling
Authors: Kelsey Rick G. , Shafizadeh Fred
Published: December 2004

It has been shown that the rate of enzymatic saccharification of cellulosic materials including “pure” cellulose (Whatman CF−11 cellulose), newsprint, lignocellulose (prehydrolyzed to remove hemicelluloses), and wood can be substantially increased by simultaneous wet milling. An enhanced hydrolysis rate was sustained above that observed for ball milling: providing a more extensive saccharification. The cellulosic substrates were wet milled with a variety of grinding elements, such as sand, glass beads, and stainless‐steel beads, agitated in a shaker bath. Simultaneous hydrolysis was achieved with a 2% substrate slurry in a 0.1M acetate buffer at 45°C and pH 5. The effectiveness of this process was dependent upon the lignified matrix of the cellulose microfibrils, the grinding elements, and the oscillation frequency of the shaker bath. Wet milling “pure” cellulose for 48 hr, with 3.5 mm glass beads and 200 oscillations/min (opm), yielded 1031 mg reducing sugar/g substrates (93% saccharification) as compared to 483 mg (44%) for the ball‐milled sample and 253 mg (23%) for the unmilled material. With the lignified substrates stainless‐steel beads (3.5 mm) were more effective than glass. For lignocellulose 529 mg sugar/g substrate (93% saccharification) could be obtained by wet milling with cellulase for 24 hr. This was about three times greater than that of the ball milled (169 mg, 30%) and 10 times greater than that of the unmilled (52 mg, 9%) substrates. The method was also effective for wood particles (60 mesh) giving 143 mg sugar/g wood (approximately 38% saccharification) in 48 hr, whereas the ball‐milled sample gave only 79 mg (21%) and the unmlilled substrate 38 mg (10%). These observations can be explained on the basis of the current crystalline theory for the morphology of the cellulosic microfibrils. The advantage of wet milling and simultaneous hydrolysis apparently depends on a continuous generation of accessible sites and sustained rapid hydrolysis rate as the saccharification proceeds, where in the pretreated substrates the hydrolysis rate slow down as the active sites are reduced.
Cellobiose hydrolysis by endoglucanase (glucan glucanhydrolase) from Trichoderma reesie: Kinetics and mechanism
Authors: Ladisch Michael R. , Gong Cheng‐Shung , Tsao George T.
Published: December 2004

Glucanohydrolase from Trichoderma reesei, having a molecular weight of 52,000, was evaluated for kinetic properties with respect to cellobiose. Results from this work include: (1) initial rate studies that show that glucanohydrolase hydrolyzes cellobiose by a competitive mechanism and that the product, glucose, inhibits the enzyme; (2) low‐pressure aqueous liquid chromatography that shows that formation of a reversion product, cellobiose, is minor and occurs in detectable amounts only a very high (90mM) cellobiose concentrations; (3) development of an equation based on the mechanism of glucanohydrolase action as determined by initial rate kinetics, which accurately predicts the time course of cellobiose hydrolysis; (4) derivation of an initial rate expression for the combined activity of cellobiase and glucanohydrolase on cellobiose. Based on data in this paper it is shown that the difference in inhibition pattern of the two enzymes could be used for determining the contamination of one enzyme by small quantities of the other.
Properties of soluble and immobilized Aspergillus niger β‐xylosidase
Authors: Oguntimein Gbekeloluwa B. , Reilly Peter J.
Published: December 2004

Aspergillus niger β‐xylosidase was characterized when in soluble form and when immobilized to alkylamine porous silica with glutaraldehyde and to alumina with titanium tetrachloride. Energies of activation averaged 13.4 KcaL/mol for the soluble enzyme, 9.0 Kcal/mol when immobilized to alumina, and 8.0 Kcal/mol when bound to silica. The highest activity of all forms of β‐xylosidase was found near pH 3. The soluble enzyme was highly stable at pH 4, where lowest rates of decay occurred, and temperature of 65°C and below. The decay rates of alumina‐bound β‐xylosidase and pH 4 and equivalent temperatures were approximately 10 times as high. Michaells constants were 0.200 and 0.262mM for o‐nitrophenyl‐β‐D‐xylopyranoside with soluble and alumina‐bound β‐xylosidase, respectively.
Production and utilization of Bacillus thuringiensis
Authors: Couch T. L. , Ross D. A.
Published: December 2004

Biological insecticide formulations based on the entomogenous bacterium. Bacillus thuringiensis, have begun to be used widely in agriculture. This spore‐forming bacillus can be grown in submerged culture and formulated to provide stable agricultural formulations compatible with aerial and ground application systems. The safety of these products to nontarget organisms and man is responsible for the growing interest in their use on a variety of crops including pastures and forests. No longer a laboratory curiosity, B. thuringiensis is an economic alternative to chemical insecticides.