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• Engineering General  (189)
• Biochemistry and Biotechnology  (106)
• 1970-1974  (295)
• 1973  (295)
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• 1970-1974  (295)
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• 1
Electronic Resource
New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 13-25
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: 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.
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• 2
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 69-84
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Various methods were tried for the immobilization of aspartase, and the preparation having the highest activity was obtained when partially purified aspartase from Escherichia coli was entrapped into polyacrylamide gel Iattice. Enzymatic properties of the immobilized aspartase were investigated and compared with those of the native aspartase. With regard to optimum pH, temperature, concentration of Mn++, kinetic constants and heat stability, no marked difference was observed between the native and immobilized aspartases.By employing an enzyme column packed with the immobilized aspartase, conditions for continuous production of L-aspartic acid from ammonium fumarate were investigated. When a solution of 1M ammonium fumarate (pH 8.5, containing 1mM MnCl2) was passed through the aspartase column at the flow rate of SV = 0.08 at 37°C, the highest rate of reaction was attained. From the column effluents, L-aspartic acid was obtained in a good yield.
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• 3
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 143-161
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Quantitative studies are reported of external film and internal pore diffusion effects for glucose oxidase immobilized on porous glass in a continuous, tubular, packed bed reactor. The McCune and Wilhelm model for external film diffusion is shown to describe these data over a particle Reynolds number range from 0.2 to 25. The Thiele analysis provides a good description of internal pore diffusion resistances. It appears that immobilized enzymes free of internal diffusional restrictions generally require the use of supports with pore sizes larger than those currently available in porous glass.
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• 4
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 951-962
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Carrier-bound immobilized α-amylases and glucoamylase have been obtained by photopolymerizing aqueous solutions containing acrylamide, a crosslinking monomer, an enzyme-reactive monomer, an oxygen scavenger, and amylase, and allowing the amylase to react with the entrapping enzyme-reactive gel matrix evolved. Partial starch hydrolyzates (28 DE corn starch syrup) have been continuously converted to 90-94% dextrose syrups in columns packed with immobilized amylases. The enzymatic heat stability of immobilized glucoamylase gels is discussed.
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• 5
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 981-992
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Wheat germ agglutinin protein, which is able to agglutinate tumor cells better than normal cells, was covalently bound to polyacrylamide gel beads. The specific binding activity of the protein was preserved on these beads and was expressed heterogeneously by the binding of mouse leukemia cells (L1210) to the protein coupled gels. The selective activity of the immobilized protein was maximal when the number of sites available to covalently couple the protein was lowest. The application of this observation to the general field of covalent immobilization of proteins and enzymes may be of considerable utility.
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• 6
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 1007-1010
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 7
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 1017-1017
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 8
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 1045-1073
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Experimental evidence is presented which indicates that both chemical and autoflocculation of microorganisms occur by the same mechanism. Basically, long chain polymeric species attach themselves between the microbial particles and agglomerate them into flocculant particles of sufficient magnitude to subside from suspension under quiescent conditions. Properties of the polymers which are produced during autoflocculation are investigated and these polymers are shown to be capable of causing the agglutination of inorganic colloids such as alumina. It is hypothesized that these biologically generated flocculating polymers could belong to a class of compounds known as transport enzymes. The experimental data qualitatively agrees with this hypothesis.
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• 9
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 1179-1188
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: A mutant of E. coli constitutive for β-galactosidase has been grown in batch culture with the carbon source, glycerol, fed at various fixed rates to the culture. High feeding rates where growth was only slightly restricted gave final enzyme levels similar to those obtained in cultures where all the glycerol was added initially. Low feeding rates resulted in breakdown of the β-galactosidase formed and gave reduced final levels of the enzyme.
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• 10
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 1189-1192
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 11
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 1123-1129
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Cellulase production by strains of Myrothecium verrucaria, Stachybotrys atra and Trichoderma viride was examined. Myrothecium verrucaria was found to give the greatest yields. A variety of media were examined as potential substrates for the industrial production of cellulase. The salts content of the medium was varied and was found to affect cellulase production. Glucose, carboxymethylcellulose (CMC), filter paper and three industrial wastes were examined as possible cellulase inducers. Filter paper was found to be the most effective, followed by sugar cane bagasse and CMC.
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• 12
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 1147-1158
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: An investigation was made on the factors influencing the acetic acid concentration in the culture liquid of the aerobic fermentations where acetie acid was used as a carbon source. The acetic acid concentration in the culture liquid changed in proportion to the amount of unutilizable acid or base supplied. This was explained by the principle of conservation of electroneutrality.Another factor affecting the acetic acid concentration in the culture liquid was bicarbonate ions which were formed by the dissolution and dissociation of carbon dioxide in the gas phase of the fermentor. The increment in bicarbonate ion concentration was equal to the decrement in the acetie acid concentration in the culture liquid.
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• 13
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 1193-1197
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 14
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 163-179
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Kinetic studies on the growth of Aspergillus strains as well as constitutive and inductive polygalacturonase formation have been made in bath fermentations, without pH control. Equations describing growth and product formation of the four-stage growth of microorganisms were applied for the first time to diauxic growth and enzyme formation of Aspergillus strains. Diauxic growth of the cultures has been found in both sucrose- and peetin-containing media. Enzyme concentration in the second transient phase, calculated by the use of new equations, proved to be negligible. In the exponential and declining phases, the calculated values of mycelial and enzyme concentrations were in good agreement with the values observed. Types of classification of the product formation of Luedeking and Piret refer to the second cycle of diauxie. The types of product formation described by Kono and Asai and Luedeking and Piret are mostly in good agreement with each other. The greatest difference has been found in the case of inductive endo-polygalacturonase formation, where the final enzyme formation could not be plotted because of the decrease (autolysis) in mycelial weight.
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• 15
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 213-216
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 16
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 257-270
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: 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.
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• 17
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 285-297
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Several strains of bacteria, isolated from marine environments, were characterized for their hydrocarbon oxidizing abilities using a complex synthetic mixture of hydrocarbons. Attempts were made at a broad classification of these organisms on the basis of their behavior towards four major groups of hydrocarbons, normal paraffins, iso-paraffins, cyclo-paraffins, and aromatics, known to be present in crude oils. Although bacteria appear to be able to oxidize hydrocarbons at random, this study has shown that it may be possible to recognize a rudimental pattern if we view their oxidative abilities in terms of groups of hydrocarbons rather than individual compounds. A study of the action of combined strains on the synthetic hydrocarbon mixture was performed. It was found that no particular benefit could be derived as compared to the use of single strains.
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• 18
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 321-330
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The concept of a maturation time (tm) for a product formation by a microbial culture is developed and a simple method is described for determining this parameter and also the product formation rate constant (kp) from batch culture experiments. The concept has been utilized in a general model for the prediction of steady state product concentrations in single-stage continuous-flow culture systems.
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• 19
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 377-393
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: A general mathematical model of the chemostat system is developed in order to define an experimental program of dynamic testing. A glucose-limited culture ofSaccharomyces cerevisiae was grown in a chemostat using chemically defined medium. The chemostat was perturbed from an initial steady state by changes in input glucose concentration, dilution rate, pH, and temperature. Dynamic responses of cell mass, glucose, cell number, RNA, and protein concentrations were measured. A number of simulation techniques were used in developing a dynamic mathematical model and in comparing the developed model with experimental data as well as the Monod model. The resulting model was found to be quantitatively accurate and superior to the Monod model. The developed model was interpreted in the light of cell physiology. Adjustment of intracellular RNA fraction was found to be rate limiting in acceleration of cell specific growth rate.
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• 20
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 441-445
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 21
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 447-453
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: A simple and efficient system for continuous ATP regeneration is described. The procedure is based on the enzyme-catalyzed reaction between carbamyl phosphate and ADP. The carbamyl phosphate was generated in situ by reaction between potassium cyanate and potassium phosphate. The enzyme, carbamyl phosphokinase, was isolated from extracts of Streptococcus faccalis and partially purified. Immobilization of the enzyme was achieved using glutaraldehyde-treated alkylamine glass giving 200-250 units of activity per gram of glass. A column of carbamyl phosphokinase on glass was used to form ATP continuously from ADP, phosphate, and cyanate and lost approximately 16% of the initial activity after 14 days operation at room temperature.
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• 22
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 395-402
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: A yeast lactase, Maxilact, was immobilized in crosslinked polyacrylamide using a bead-polymerization technique. The polymer beads obtained, containing the entrapped enzyme, were used for the preparation of lactose-free milk. The binding yield of the enzyme and residual enzymic activity in the “enzyme beads” were studied as a function of the amounts of monomeric acrylamide and cysteine and bovine serum albumin present as protecting agents in the monomer-enzyme solution prior to polymerization. A maximum of about 75% of the enzyme could be immobilized using a 20% (w/v) solution of acrylamide plus N, N′-methylenebis-acrylamide, whereas the highest activity quotient (bound to free) of about 60% was observed on using a 25% solution. The presence of cysteine increased the activity by up to 30% and that of serum albumin up to about 15%.
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• 23
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 419-439
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The synthesis of extracellular enzymes by microorganisms frequently occurs under genetic control. A simple two-parameter model is developed describing the degree of repression or induction in fermentation media.The case of substrate utilization by an extracellular enzyme was analyzed for a vegetable oil-lipase-yeast system. It is shown that fatty acids released by the lipase may accumulate in the early stage of growth and exert an influence on the limiting after which relatively little repression or induction takes place.Expressions are also derived for growth and extracellular enzyme synthesis in single-and multistage continuous cultures. When the cells grow on a directly available soluble substrate, the specific enzyme synthesis is maximal at low dilution rates in the case of repression and at high dilution rates in the case of induction. If the substrate is not directly available, a single continuous stirred tank reactor stage may not be sufficient for efficient substrate utilization; for fermentation processes where an insoluble has to be broken down before the cells can assimilate it, a plug flow type fermentor rather than a mixed chemostat may prove more satisfactory.
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• 24
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 483-492
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: A study was made to determine the controlling mass transfer resistance in the overall reaction rate for conversion of maltose to glucose, catalyzed by glucoamylase immobilized onto porous glass. For normal operation of a packed column and air-stirred batch reactor, the rate controlling step was found to be the internal resistance of simultaneous pore diffusion and chemical reaction. Experimental effectiveness factors were determined and are compared with those derived from a theoretical diffusion model based on Michaelis-Menten kinetics. Also given are temperature and pH relationships for the free and immobilized glucoamylase.
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• 25
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 533-549
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: A periodic countercurrent whole beer process was developed for the recovery of novobiocin to eliminate the high cost of mycelium filtration and accompanying antibiotic losses in the filter cake. In such a process screened, but unfiltered, novobiocin fermentation beer is contacted with a special grade of an anionic-exchange resin in a series of specially designed, well mixed columns. Each column is fitted with a screen sized to retain resin within the column but allow the cells to press. Periodically the lead column is isolated from the column train, washed free of beer solids, and eluted. A freshly eluted column is placed in the trail position to allow countercurrent operation. The eluate is then processed to crystalline product.A mathematical model for the sorption of novobiocin was developed based on a suitable continuity equation and mass transfer and equilibrium relationships determined in the laboratory. Digital computations of this model correlated well with laboratory and pilot plant data, and predicted well the performance of the production units. This simulation has been in continued use to predict and reoptimize plant operation as process changes (such as improved beer titers, increased production rate, and the evaluation of superior ion-exchange resins) occurred or were anticipated.
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• 26
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 571-578
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 27
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 597-602
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 28
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 611-647
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 29
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 707-728
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: 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.
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• 30
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 755-782
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: A new correlation is given for the prediction of the volumetric coefficient for mass transfer (KLa) in stirred tanks from dispersed gas bubbles to basal salt solutions of ionic strengths representative of fermentation media. The correlation includes the effects of both the operating parameters (agitation power per unit volume and gas superficial velocity) and the physicochemical properties of the system: interfacial tension, viscosity, density, diffusion, coefficient and, in particular, ionic strength. The effect of the latter was found to be most significant in the Newtonian systems of water-like viscosity investigated; no previous correlations have included the effect of ionic strength. KLa values were determined by using a dissolved oxygen probe to monitor the steady-state oxygen tension in continuous flow experiments, and/or the rate of change of oxygen tension in unsteady-state semibatch experiments. In the latter cases, results were computed by a nonlinear, least squares computer program which fitted the experimental data to a model of probe transient response characteristics. The general applicability of the model and the computational procedure was verified by comparing the results to those obtained with the same electrolyte solution in the steady-state mode. The experiments were run over a wide range of agitation power inputs, including those typical of both soluble- and insoluble-substrate fermentations. The correlation appears to be valid for both oxygen mass transfer with and without homogeneous chemical reaction in the liquid phase; in the former case, for example, sulfite oxidation, knowledge of the chemical reaction enhancement factor is required. In addition to predicting oxygen transfer capabilities, the correlation may be used for other sparingly soluble gases of interest in fermentation systems, such as methane, hydrogen, and carbon dioxide.
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• 31
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 817-818
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 32
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New York, NY [u.a.] : Wiley-Blackwell
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 33
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 467-481
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Enzymes can be encapsulated within a semipermeable membrane which allows reactants to enter and the products to diffuse out. The mass transport from the external fluid to the membrane and the combined mass transport and biochemical reaction from the membrane inwards can be modeled with recognized formulations; measurements of the overall reaction rate lead then to estimates of the permeability of the membrane itself.With capsules enclosing catalase, the permeability of collodion membranes to H2O2 is found to be large (〈2 × 10-2cm/sec) in comparison to rates in the other two diffusion zones. For this first-order reaction system, an analytical solution to the transient case of the well-stirred finite bath is found using the Laplace transform. With capsules enclosing urease, the nonlinear Michaelis-Menten kinetics apply to the enzymatic step. The steady-state operation of a column packed with urease microcapsules is analyzed with the aid of numerical computation and the membrane permeability for urea is found to be 10-3cm/sec.
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• 34
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 565-569
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 35
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 905-916
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: It is shown that two steady states exist in certain regions of operation of a 2-liter continuous stirred tank biological reactor. Transition was made from one steady state to another by applying shock loads of either phenol substrate which is inhibitory to the culture at high concentrations or by adding large additional amounts of concentrated organisms. The existence of the multiple steady states is ascribed to the existence of wall growth, and their position is determined by the amount of wall growth. Transient behavior of the system did not follow the predictions of the simple wall growth model but the culture appeared to undergo a lag period immediately after applying the shock load to the system. It is concluded that the stability of a continuous culture utilizing an inhibitory substrate is improved by increasing the degree of wall growth and decreasing the substrate feed concentration. It is also concluded that small scale experiments can usually not be interpreted correctly unless the effect of wall growth is taken into account.
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• 36
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 1159-1177
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: A simplified model of cell metabolism, consisting of a series of linked reversible enzymatic reactions dependent on the concentration of a single external substrate has been developed. The general mathematical solution for this system of reactions is presented. This general solution confirms the concept of a rate-limiting step, or “master reaction”, in biological systems as first proposed by Blackman. The maximum rate of such a process is determined by, and equal to, the maximum rate of the slowest forward reaction in the series.Of practical interest in modeling the growth rate of cells are three cases developed from the general model. The simplest special case results in the Monod equation when the maximum forward rate of one enzymatic reaction in the cell is much less than the maximum forward rate of any other enzymatic reactions.More realistic is the case where the maximum forward rates of more than one enzymatic reaction are slow. When two slow enzymatic reactions are separated from each other by any number of fast reactions that overall can be described by a large equilibrium constant, the Blackman form results: \documentclass{article}\pagestyle{empty}\begin{document}$$\mu = [S]/A, \rm{when} [S] 〈 A\mu_{\rm{max}}$$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$$\mu = \mu_{\rm{max}}, \rm{when} [S] \rm{〉} A\mu _{\rm{max}}$$\end{document}A third case is that in which two slow enzymatic steps are separated by an equilibrium constant that is not large. Unlike the Monod and Blackman forms, which contain only two arbitrary constants, this model contains three arbitrary constants: \documentclass{article}\pagestyle{empty}\begin{document}$$[S] = \mu A + \frac{{\mu B}} {{(\mu_{\rm{max}} - \mu)}}$$\end{document}The Monod and Blackman forms are special cases of this three constant form.In comparing equations with two arbitrary constants the Monod equation gave poorer fit of the data in most cases than the Blackman form. It is concluded that workers modeling the growth of microorganisms should give a t least as much consideration to the Blackman form as is given to the Monod equation.
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• 37
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Biotechnology and Bioengineering 15 (1973), S. 27-45
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: 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.
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• 38
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Biotechnology and Bioengineering 15 (1973), S. 93-115
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Collagen was used as carrier for the immobilization of invertase, lysozyme, urease, glucose oxidase, penicillin amidase, and glucose isomerase. Immobilization was accomplished by either impregnation of a preswollen collagen membrane with enzyme solution or electrocodeposition of collagen and enzyme from a collagen dispersion containing dissolved enzyme. The collagen-enzyme complexes prepared are in membrane form.Membranous collagen-enzyme complexes were used to construct biocatalytic reactors such as the capillaric coil modular reactor. Such biocatalytic reactors were used in a recirculation system for the conversion of substrates. The biocatalytic reactors showed initial decreases of activity to stable limits which are maintained over a large number of reactor volume replacements. The stable limits correspond to approximately 35% of the initial activities for lysozyme and invertase, 25% for urease, 15% for glucose oxidase.The mechanism of complex formation between collagen and enzyme involves multiple salt linkages, hydrogen bonds, and van der Waals interactions. This protein-protein interaction which leads to stable complexes by both impregnation and electrocodeposition processes is unique among the enzyme immobilization methods currently available.
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• 39
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Biotechnology and Bioengineering 15 (1973), S. 85-91
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Flavor enhancing nucleotides may be produced by streptomycetes. Mutants of streptomyces 772 were found to produce, under ordinary fermentation conditions, considerable amounts of 5′-IMP and 5′-XMP, but only traces of 5′-GMP. This was probably due to the feedback inhibition of the end product GMP. It was shown that through suitable fermentation techniques it was possible to overcome this internal control mechanism, leading to increased yields of 5′-GMP.
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• 40
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 129-142
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Methods for the production of protein concentrates, with a low content of nucleic acid, in kilogram quantities from yeast have been studied with the aid of equipment designed for operation on pilot-plant scale. The influence of drum drying and mechanical disintegration on the nutritive value of the yeast was also investigated. Drum drying and mechanical disintegration improved the nutritive value of the yeast but high extractability of protein and nucleic acid was only obtained after mechanical disintegration.Protein concentrates without and with cell walls were produced from mechanically disintegrated yeast. The different fractions which were obtained when separating cell walls and precipitating protein by heating at alkaline pH, were analyzed. After protein precipitation, about 90% of the RNA could be precipitated from the supernatant by addition of acid, giving a product containing 50% RNA of the dry weight. The protein precipitate obtained after cell wall separation had an RNA content of less than 2% and contained 70-l75% of the amino acids in the starting yeast material. Protein concentrates containing cell walls were produced by precipitating protein by heating at alkaline pH directly after mechanical disintegration. The content of RNA was about 2% and the yield of amino acids was 70-80%. It was found that the nutritive value of the protein concentrate was higher than that of the starting yeast material. To produce such a protein concentrate on a large scale, the process described can probably be employed.
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• 41
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 197-200
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 42
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 217-221
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 43
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 239-255
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Glucose-limited chemostat cultures of Candida utilis were cultivated at various pH levels (3.0-7.5), temperatures (15-37.5°C), dilution rates (0.06-0.42 hr-1), and with different nitrogen sources (NH4+ and NO3-). The ratio of total nucleic acid to protein increased with increase in dilution rate at constant temperature and decreased with increase in temperature at constant dilution rate. The pattern of these variations is consistent with the hypothesis that the nucleic acid to protein ratio is a function of the ratio of the actual dilution rate to the critical dilution rate corresponding to each one of the cultivation temperatures. This ratio is called “reduced dilution rate.” A basis is proposed on which various microorganisms may be compared with respect to the ratios of cell protein to nucleic acid, RNA, ribosomal RNA, and polysomes.
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• 44
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Biotechnology and Bioengineering 15 (1973), S. 331-358
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Insofar as saturation kinetics are applicable to the growth of phytoplankton in laboratory experiments and to growth in nature, the computer modeling of intracellular nutrient partitioning in populations of cells can lead to better understanding of the dynamics of natural populations.A three-compartment mathematical model was developed to represent a phytoplankton population having the capability to store nitrogen in a nitrate-limited environment. Parameters were estimated by fitting the model to data from two chemostat experiments reported by Caperon (1968). The model was used to simulate growth dynamics observed in chemostat and batch experiments. The model demonstrated the changes which may occur in the nitrogenous constituents of a phytoplankton population with time and environmental conditions. The model also demonstrates three phenomena which have been observed in field and laboratory experiments but which are not represented by the customary Monod model: (1) uptake rates may significantly exceed not growth rates, (2) high growth rates may be encountered at very low environmental nitrate concentrations, and (3) the ratio of internal nitrogen to population size may change significantly during a study period. It is suggested that the amount of nitorgen in storage may be used as an indicator of the physiological state of a monospecific population.Parameters for the one-compartment Monod model were estimated by customary methods form data generated by the three-compartment model. It was shown that difficulties encountered in estimating the yield coefficient and the decay coefficient may be attributed to the intracellular storage phenomenon. It was also demonstrated that the one-compartment Monod model was inadequate to accurately represent population growth in chemostat experiments when intracellular storage is a significant factor.
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• 45
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Biotechnology and Bioengineering 15 (1973), S. 413-418
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Many chemical and food processing wastes are deficient in nitrogen, and must therefore be supplemented with domestic sewage or ammonia to dispose of them by conventional biological treatment. A more economical treatment, especially of strong wastes, is possible by maintaining a semipure culture of nitrogen-fixing bacteria in a stirred aerated tank. When operated as a chemostat with 4 to 6 hr detention time, removal of 85% of the COD is possible in a single step without the need for clarifiers or digesters. A clarified effluent could also be produced by flotation or sedimentation of the flocculated bacteria. In that case there would be 99% removal of COD and a reduction in the amount of sludge by two-thirds over the conventional activated sludge process.
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• 46
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Biotechnology and Bioengineering 15 (1973), S. 493-503
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Penicillin amidase, an enzyme which hydrolyzes benzylpenicillin to 6-aminopenicillanic acid and phenylacetic acid, is produced by Bacillus megaterium ATCC 14945 as an extracellular enzyme. We used this system as a model to examine the effects of nitrogen, sulfur, and phosphorous limitation on enzyme production in continuous culture. For these studies, we developed a minimal medium for B. megaterium which contained histidine as the sole nitrogen source. Batch experiments showed that this enzyme is produced as a growth-associated metabolite. Enzyme production was shown to be a function of the growth-limiting conditions and the concentration of the inducer, phenylacetic acid. Sulfur limitation in continuous culture yielded enzyme activities approximately three to five times those observed in nitrogen- and phosphorous-limited chemostats. These results are discussed in terms of the environment's influence on enzyme production in continuous culture.
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• 47
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Biotechnology and Bioengineering 15 (1973), S. 551-560
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: A substrain of Bacillus cereus 569/H produced under controlled fermentation conditions in a pilot plant fermentor phospholipase-C. A partially purified preparation showed good storage stability as a lyophylized powder and in frozen solutions. The preparation contained very small amounts of phosphomonoesterase and proteolytic activities and essentially no ribonuclease activity. The level of hemolytic activity of the preparation was much lower than that of a commercial preparation of phospholipase-C from Clostridium. Treatment of sarcoplasmic reticulum membrane with phospholipase-C from B. cereus and from Clostridium showed that the B. cereus enzyme caused hydrolysis of 96% of the membrane phospholipids whereas the enzyme from Clostridium could hydrolyze only 80% of the phospholipids.
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• 48
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Biotechnology and Bioengineering 15 (1973), S. 583-588
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 49
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 607-610
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
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• 50
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Biotechnology and Bioengineering 15 (1973), S. 743-754
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: DL-Norleucine, a nonsulfur analogue of methionine was found to markedly stimulate synthesis of cephalosporin C by Cephalosporium acremonium strain CW19 in three different chemically defined media. Methionine, but not norleucine, stimulated cephalosporin C biosynthesis in a crude medium. The lack of stimulation by norleucine in complex medium was shown to be due to lack of uptake of this amino acid by mycelia growing in such a medium. In defined media containing a suboptimal methionine concentration, norleucine stimulated antibiotic production up to the level reached by optimal methionine. At an optimal dose of methionine, norleucine elicited no further increase in cephalosporin C production, indicating that these two amino acids act by the same mechanism. The data strongly indicate that stimulation by methionine is not a function of its ability to donate sulfur for antibiotic formation. Methionine was found to neither repress nor inhibit cysteine metabolism.
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• 51
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Biotechnology and Bioengineering 15 (1973), S. 795-803
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: 5′Xanthylic acid was efficiently converted to 5′guanine nucleotides (5′GMP, 5′GDP, and 5′GTP) without being degraded to guanine via 5′GMP by decoyinine resistant mutants of strain KY 13315 which had been isolated from Brevibacterium ammoniagenes and was practically devoid of 5′nucleotide degrading activity. The concentration of phosphate in the medium showed a profound effect on the ratio of the accumulated 5′guanine nucleotides, making it possible to direct the fermentation towards 5′GMP or 5′GTP. A direct accumulation of 5′guanine nucleotides from carbohydrate was possible by mixed cultivation of a 5′XMP accumulating strain and a 5′XMP converting mutant. A maximum concentration of 9.67 mg of 5′guanine nucleotides per ml was obtained directly from glucose in such a mixed culture.
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• 52
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Biotechnology and Bioengineering 15 (1973), S. 879-888
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The steady state, nonlinear diffusion equations which describe reactions in constrained enzyme solutions are of great interest in many biological and engineering applications. As in other types of nonlinear differential equations, exact analytical solutions do not exist except in some simplified cases. In this paper, a general procedure is presented for solving numerically for the substrate concentration profile and effectiveness factor utilizing the transformation method suggested by Na and Na. Design correlations for enzyme solutions constrained within spherical membranes are included. The use of a unique definition of the Thiele Modulus in these charts permits the clear illustration of the effects of substrate concentration and external mass transfer resistances on the overall effectiveness factor for the catalyst particle.
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• 53
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Biotechnology and Bioengineering 15 (1973), S. 933-949
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The response of aerobically growing heterogeneous microbial populations of sewage origin to step increases and decreases in pH were studied in both once-through and cell recycle systems. The pH range studied was 2.7 to 8.0. All studies were conducted at a dilution rate of 0.125 hr-1, and all shocks were administered from a base or preshock pH level of 6.4 to 6.7. In each experiment, the preshock or initial “steady state” was assessed, the pH of the feed changed, and the resulting transient behavior of the system examined until attainment of the new or final “steady state” was approached. The major objectives of the work were to characterize the nature of the response with respect to biomass and effluent substrate concentrations, types of microbial populations present and chemical composition of the biomass, and to obtain guidelines as to allowable change in pH in waste streams. It was found in once-through systems that substrate removal efficiency recovered from pH levels as low as 3.0 after rather long periods of transient leakage of substrate. Cell recycle attenuated the severity of substrate leakage. In all cases of severe acid shock, the microbial population changed from predominantly bacterial-protozoan to one consisting predominantly of filamentous fungi. Changes in chemical composition of the sludge (protein and carbohydrate content) were consistent with the population changes. Based upon the results, it can be conservatively estimated that changes in pH of no more than one unit from the neutral preshock range can be tolerated without possible disruption of biochemical efficiency of substrate removal.
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• 54
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ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 55
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Biotechnology and Bioengineering 15 (1973), S. 299-308
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The effect of potassium sorbate addition to a continuous culture of Saccharomyces cerevisiae was observed. The influence on the yeast performance depended on the way the inhibitor was added. The unsteady state continuous method seems to be the best one to obtain microorganisms' adaptation to inhibitors, and for the experimental study of microbial inhibition.
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• 56
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Biotechnology and Bioengineering 15 (1973), S. 359-375
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: New methods of crosslinking enzyme molecules inside a matrix with or without an inactive protein are described. Enzyme activity yields range between 30 and 80% of the activity of the untreated preparations. Even fragile enzyme systems, for instance those using mobile cofactors, can be efficiently immobilized. Increased resistance towards heat denaturation and proteolysis results.
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• 57
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Biotechnology and Bioengineering 15 (1973), S. 403-412
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: 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.
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• 58
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ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 59
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 15 (1973), S. 589-596
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 60
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ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 61
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Biotechnology and Bioengineering 15 (1973), S. 677-692
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Eighteen ultrafiltration membranes ranging in molecular weight cutoff ratings from 500 to 300,000 were tested with water, 0.5M NaCl solution, and, in some cases, with macromolecules and urea in a 3-in. stirred filter cell. Approximately half of the membranes showed a significant decrease in filtration rate during the first 24-hr period. The steady-state rates were less than the manufacturers' rating for about two thirds of the membranes, the discrepancy being greater for the membranes with high molecular weight cutoffs.The filtration rates were linearly dependent on applied pressure over the range at least as great as 15 to 55 psig. The rate decreased as the concentration of macromolecules such as transfer ribonucleic acid (tRNA) increased; the rate for a concentration of 3 mg tRNA/per ml was one-fourth of that observed when no tRNA was present. Some increase in rate (∼33 to 50%) was obtained by increasing the stirring speed from 100 rpm to 1000 rpm.The membranes were effective for desalting and concentration of macromolecules but not for separation of large molecules from each other, such as tRNA from bovine serum albumin. Easily denatured molecules such as catalase were not deactivated by filtration at 4°C.
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• 62
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Biotechnology and Bioengineering 15 (1973), S. 783-794
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Barely β-amylase (α-1,4-glucan maltohydrolase, EC 3.2.1.2) has been immobilized by covalent fixation to amino derivatives of epichlorohydrin crosslinked Sepharose mediated by cyclohexyl isocyanide and acetaldehyde. The enzyme conjugates contain up to 35% of the total activity of the β-amylase added to the coupling mixture. The profiles of activity versus pH and ionic strength are essentially the same for free and immobilized β-amylase, whereas the resistance to inactivation during storage and use is considerably enhanced by immobilization. Columns with immobilized β-amylase have been used for continuous degradation of starch. At 45°C, half of the initial activity remains after seven weeks, and the corresponding figure at 23°C is 85 percent.
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• 63
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Biotechnology and Bioengineering 15 (1973), S. 811-815
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
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• 64
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Biotechnology and Bioengineering 15 (1973), S. 827-829
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
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• 65
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Biotechnology and Bioengineering 15 (1973), S. 845-859
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Of 24 different polymer and surfactant materials examined, a carboxypolymethylene (“Carbopol”) was found to cause enhancement of respiration rates in an Aspergillus niger culture 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.
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• 66
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Biotechnology and Bioengineering 15 (1973), S. 917-925
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: 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.
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• 67
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Biotechnology and Bioengineering 15 (1973), S. 1023-1037
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Studies are reviewed on the composition of hemolymph from Japanese beetle larvae, Popillia japonica. This research was conducted to determine the chemical environment required for sporulation of the milky disease organism, Bacillus popilliae. Amino acids, proteins, organic acids, lipids, carbohydrates, and oxygen content were determined in hemolymph from healthy and diseased larvae. Oxygen content of hemolymph was measured by microelectrodes implanted in the hemocoel of living larvae. Vegetative growth of the pathogen reduces the dissolved oxygen; however, as sporulation occurs, oxygen concentration approaches normal values. Trehalose, the major hemolymph sugar, is reduced by ca. 50% during the course of milky disease. Neutral lipids, phospholipids, and hydrocarbons decrease markedly with infection. Both branched-chain and normal alkanes occur in hemolymph. Milky disease causes an increase in concentration of pyruvic, malic, glycolic, tartaric, and glyoxylic acids. The major hemolymph protein, a lipoglycoprotein, has a mol. wt. of ca. 500,000. Reduced concentration of this protein is accompanied by the appearance of a smaller protein. Amino acids that increase significantly as a result of infection are: Glutamic acid, aspartic acid, β-alanine, phenylalanine, threonine, lysine, and serine. Hemolymph contains few peptides of low molecular weight.