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  • Life and Medical Sciences  (4,835)
  • Biochemistry and Biotechnology  (3,767)
  • 1995-1999  (7,331)
  • 1965-1969  (1,271)
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  • 1
    Electronic Resource
    Electronic Resource
    Effect of high substrate concentration and cell feedback on kinetic behavior of heterogeneous populations in completely mixed systems (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 207-237 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Growth kinetics of heterogeneous populations of sewage origin were studied in completely mixed reactors of the once-through type at a high concentration of incoming substrate, 3000 mg/l glucose, and in systems employing cell feedback or sludge recycle at an incoming substrate concentration of 1000 mg/1 glucose. The recycle flow rate employed was 25% of the incoming feed flow, and the concentration of cells in the recycle was maintained as closely as possible at 150% of the cell concentration in the reactor. Studies were made at various dilution rates. Throughout these studies, batch experiments using cells grown at the various dilution rates were made to determine ks and μm values. As in previous studios using heterogeneous populations, the relationship between specific growth rates μ and substrate concentration S was represented better by the Monod equation than by any other which was tested. The growth “constants” μm, ks, and Y were found to fall in the same general range as those determined in previous studies in once-through systems operated at 1000 mg/l glucose. It was observed that cell recycle, even at the relatively low concentration factor employed in these studies, greatly enhanced the flocculating and settling characteristics of the cells.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260110207
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  • 2
    Electronic Resource
    Electronic Resource
    Growth potential of a variation of eagle's minimum essential medium for spinner cultures (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 263-266 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260110209
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  • 3
    Electronic Resource
    Electronic Resource
    Masthead (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260110301
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  • 4
    Electronic Resource
    Electronic Resource
    The isolation of an aliphatic amidase from Pseudomonas aeruginosa (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 283-292 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A pilot-scale process for the isolation of an aliphatic, amidase from Pseudomonas aeruginosa has been developed. A constitutive, partially irrepressible mutant was employed to give a high initial enzyme concentration. An existing laboratory isolation procedure has been scaled up and modified particularly by substitution of polyethylene glycol for ammonium sulfate precipitation as the first stage in the conversion of the fractionation to continuous operation. Full recovery of activity was achieved with the modification. The recovery of enzyme from a subsequent chromatographic stage was 85% and the maximum overall purification was 28-fold.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260110303
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  • 5
    Electronic Resource
    Electronic Resource
    Kinetics of fermentation processes (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 293-321 
    Details
    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 fermentation processes were made and a general equation of production rate was newly presented applying the kinetic theory on mierobial cell growth which was reported previously by the authors.l,2 Equations for product concentration in fermentation time courses were derived by developing mathematically the general equation of production rate, and characteristic properties of fermentation processes were clarified. Some examples of fermentations were analyzed kinetically using the new kinetic theory. The calculated values of product, and cell concentrations were in good agreement with the observed values.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260110304
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  • 6
    Electronic Resource
    Electronic Resource
    Measurement of heat evolution and correlation with oxygen consumption during microbial growthThis paper was presented in part at the 154th Meeting of the American Chemical Society, Chicago, III., Sept. 11, 1967. (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 269-281 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A procedure for measuring the rate of heat production from a fermentation has been developed. The method is based on measuring the rate of temperature rise of the fermentation broth resulting from metabolism, when the temperature controller is turned off. The heat accumulation measured in this manner is then corrected for heat losses and gains. A sensitive thermistor is used to follow the temperature rise with time. This procedure is shown to be as accurate as previous methods but much simpler in execution. Using this technique, the rate of heat production during metabolism was found to correlate with the rate of oxygen consumption. Experiments were performed using bacteria (E. coli and B. subtilis), a yeast (C. intermedia), and a mold (A. niger). The substrates investigated included glucose, molasses, and soy bean meal. The proportionality constant for the correlation is independent of the growth rate, slightly dependent on the substrate, and possibly dependent On the type of organism growth. This correlation has considerable potential for predicting heat evolution from the metabolism of microorganisms on simple or complex substrates and providing quantitative parameters necessary for heat removal calculations.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260110302
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  • 7
    Electronic Resource
    Electronic Resource
    The design, construction, and characteristics of a new long-lived steam sterilizable oxygen electrode (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 323-335 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A steam sterilizable oxygen electrode for fermentor use is described. The electrode has a silver cathode, lead anode, phosphate electrolyte, and a membrane of a fluorinated ethylene-propylene copolymer film (FEP.).The electrode has a linear response to partial pressure of oxygen from 1.5 × 10-2 to 103 mm Hg.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260110305
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  • 8
    Electronic Resource
    Electronic Resource
    The conversion of benzyl penicillin to 6-aminopenieillanie acid using an insoluble derivative of penieillin amidase (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 337-348 
    Details
    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 was extracted from Escherichia coli ATCC 9637, grown on phenylacetic, acid and glutamate, and purified by fractional ion with streptomycin sulphate, ammonium sulphate and polyethylene glycol, followed by chromatography on DEAE-cellulose. The purification factor was 100-200 × and the overall yield was about 115%. The enzyme was chemically attached to derivatives of cellulose and the kinetics of these insolubilized penicillin amidase preparations was investigated.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260110306
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  • 9
    Electronic Resource
    Electronic Resource
    The kinetics of β-galactosidase attached to porous cellulose sheets (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 363-380 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The properties of β-galactosidase attached to cellulose and DEAE-cellulose sheets arc described. Those insoluble enzyme derivatives obey the Michael-Menten relationship but, the measured kinetic parameters are very dependent on the flow conditions. The results of long-term stability tests are given.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260110308
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  • 10
    Electronic Resource
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    Preparation and use of insolubilized amyloglucosidase for the production of sweet glucose liquors (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 349-362 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Amyloglucosidase (EC. 3.2.1.3), partially purified from an Aspergillus species, was chemically attached to DEAE cellulose using the bifunctional reagent 2-amino-4,6-dichloro-s-triazine. The action of the insolubilized enzyme derivative on dilute maltose and dextrin solutions was studied in a packed bed. A second and deeper bed was used to demonstrate the possibility of a continuous process for raising the dextrose; equivalents of “glucose” liquors of high concentration formed by acid hydrolysis of maize starch.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260110307
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  • 11
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    An introduction to the symposium on hydrocarbon fermentation, third international fermentation symposiumThe symposium was held on Tuesday, September 3, at Rutgers University, New Brunswick, New Jersey. (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 381-381 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260110309
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  • 12
    Electronic Resource
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    Clutivation of yeast on gas oil (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 383-391 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The results achieved by the cultivation of the yeast. Candida lipolytica on gas oil are referred. By using a distillation fraction of gas oil distilling between 180-400°C, containing 10-20% of n-alkanes, the optimal condition for biomass production and deparaffination were estimated for various dilution rates and various amounts of gas oil in the medium. The main factor, which influences the yield coefficient by hydrocarbon fermentation is the polyauxie of the hydrocarbon substrate. The penetration of dispersed hydrocarbons into the yeast cell is demonstrated on electron micrographs and the velocity and reversibility of this process is estimated by using tritium-traced hexadecane.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260110310
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  • 13
    Electronic Resource
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    Composition of cell material and biological value of the cellular protein of a micrococcus strain grown on hydrocarbons (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 409-416 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A Micrococcus cerificans strain was grown on simple media with n-hexadecane or gas oil as sole carbon sources. Samples of cellular material recovered from hexadecane or gas oil fermentations do not appear to differ significantly in their composition. The protein content varied from 68 to 75%. With the exception of sulfur amino acids the amino acid distribution compares favorably with the FAO standard reference protein.The biological value of cell protein recoveered from hexadecane fermentations was 67 (cascin, 70). In the case of gas oil grown cells, the cell material recovered had to be completely purified in order to improve its protein quality. After fully extraction of undersirable fraction with petroleum ether in a Soxhlet apparatus the biological value observed was 63.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260110312
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  • 14
    Electronic Resource
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    Continuous phased culture - A technique for growing, analyzing, and using microbial cellsIssued as N.R.C. No. 10941. (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 843-851 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous phased growth produces a culture in which most of the cells in the population are in the same stage of their development. The cell, thereby amplified by the size of the synchronous population, may be examined in the phased culture at any desired growth rate. Changes taking place in the cell after the cell cycle, i.e., post-cycle changes, may be examined by a modification of the procedure. Further systematic applications of the method permit a rational approach to problems of cell growth and metabolism.The phasing technique recognizes the cells as the fundamental unit for experimental investigation, and offers a great potential in the analysis of the cell throughout its cycle, a relatively unexploited field in cell physiology and fermentation. Experiments with yeasts and bacteria illustrate some of the applications and progress made so far.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260110510
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  • 15
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    Studies of fungal growth and intermediary carbon metabolism under steady and non-steady state conditions (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 785-804 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The physiology of Aspergillus nidulans strain 224 has been studied under conditions of batch- and glucose-limited chemostat-culture and the effect of different steady state growth rates and dissolved oxygen tensions (DOT) examined. Measurements of the specific activities of selected glucose enzymes, the extent of oxygen uptake inhibition by glycolytic inhibitors, and radiorespirometric analyses were made in order to follow the variations in glucose catabolism, which occurred under these conditions. Greatly increased activity of the hexosemonophosphate (HMP) pathway was found during: (i) exponential growth of batch cultures; (ii) at near maximum specific growth rates (μ = 0.072 hr-1) (DOT = 156 mm Hg); and (iii) at low DOT levels (〈30 mm Hg) (μ = 0.050 hr-1) in chemostat cultures. These changes in glucose eatabolism have been discussed in terms of the biosynthetic demands of the fungus under the influence of changing growth pressures. Preliminary studies also have been made of transition state behavior following stepwise alteration of the DOT. A new steady state was established after 4-5 culture doublings during which period an “overshoot” in HMP pathway activity occurred; these kinetics are indicative of a derepression of certain glucose enzymes. Low molecular weight phenols are synthesized during the exponential phase in batch cultures and these are further metabliized to a major secondary metabolite, melanin, at the onset of stationary phase conditions. The kinetics of tyrosinase production in steady state chemostats differs from those that might be predicted for an enzyme associated solely with secondary metabolism. A primary physiological role for this oxidase in Aspergillus nidulans has been postulated.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260110508
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  • 16
    Electronic Resource
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    Cell growth and population activity of Saccharomyces cerevisiae in two-stage continuous cultivation (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 853-862 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous culture in a cascade of vessels with the addition of supplemental nutrients to any stage permits adjustment of the physiological state of the culture in each stage to best achieve a desired performance goal. The yeast Saccharomyces cerevisiae in two-stage continuous cultivation was selected as a model system. With conditions in the first stage held constant- at a selected glucose concentration in the feed stream, dilution rate for the second stage was varied. Cell numbers, dry weight, glucose concentration, respiration coefficient, and titers of several enzymes were determined. The seed rate was defined as the ratio of glucose concentration in the feeds to stage 1 and to stage 2. At low seed rates, the calculated specific growth rate in the second stage was proportional to dilution rate. At higher seed rates, the specific growth rate based on dry weight behaved differently from that based on cell numbers, and the dependence on dilution rate was not linear.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260110511
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  • 17
    Electronic Resource
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    Predator-prey relationships in a model for the activated process (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 887-907 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The primary objective of this paper was to develop a mathematical description for the food chain, Because of the interdependence of the elements in this food chain, continuous oscillations among the variables are possible. A set of three differential equations was obtained to describe the above system in a continuously fed stirred tank reactor. The differential equations obtained were examined to characterize the possible types of solutions. A limit, cycle solution was obtained for some values of the system parameters.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260110514
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  • 18
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    Effect of total illumination upon continuous Chlorella production in a high intensity light system (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 863-874 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A high intensity light system (HILIS) was designed and constructed to define the environmental parameters affecting production of algae. The HILIS incorporates the basic concepts of an aerobic fermenter for heterotrophic cells with high intensity illumination for photosynthetic studies. Of nine parameters considered, temperature and light intensity studies using Chlorella 71105 have been completed. Total illumination was varied from 25,000 to 300,000 lumens (30 times intensity of sunlight as measured at earth's surface) in 7.7-1, culture. The effect of illumination upon growth was measured as cell concentration and total daily algal production when operating the HILIS as a continuous system at a dilution rate of 0.91 per day.Growth may be expressed as a long function of illumination. A maximum algal concentration of 25.5g/l., dry weight basis, was attained at 300,000 lumens.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260110512
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  • 19
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    Homogeneous cultivation of animal cells for the production of virus and virus products (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 875-885 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Homogeneous technique facilitates the cultivation of large quantities of cells, reduces the risk of contamination by eliminating many manipulations, and makes practical the control of conditions such as pH and oxygen tension. Although most animal cells will not multiply in free suspension, certain cell lines have lost the requirement of being attached to a solid surface. These cells can be subcultured indefinitely but have some resemblance to cancer cells such as their abnormal karyotype. Certain cell linen developed from human embryonic tissue maintain their diploid character after repeated subculture and would seem to be ideal for the production of vaccines. However, strict regulations exist for viral products for human injection in that only cells taken from normal tissue and subcultured but once may be used.A microcarrier method in which cells adhere to DEAE-Sephadex beads permits a suspension culture which may be termed quasihomogeneous. The attached cells may be retained by sedimentation or by screening as the medium is replaced. Cell debirs from the original tissue is difficult to remove from microcarrier cultures; modifications of the trypsinization technique have alleviated but not solved this problem.Conditions for virus replication can be less critical than those for cell growth in that oxygen tension seems to have little influence on virus production. In cases where rate of virus production increases with specific growth rate of cells, homogeneous culture would have a advantage in maintaining a high cell mogeneous culture would have a valuble advantage in maintaining a high cell growth rate for a longer time. Some virus infections destroy cells, but others cause little change in cellular mteabolism except that virus is continually produced. The latter type can be conducted with a microcarrier in continuous culture with a virus titer exceeding 107 plaque forming units per milliliter for over 50 days with Rubella-infected BHK cells.
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    URL: http://dx.doi.org/10.1002/bit.260110513
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  • 20
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    Introduction to the symposium on engineering aspects of fermentation (second part) (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 909-909 
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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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260110515
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  • 21
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    Performance of a perforated plate column as a multistage continuous fermentor (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 911-926 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Microorganisms were continuously cultivated in multistage column consisting of ten perforated plate sections to which medium and air were supplied concurrently from the bottom.At steady state the cell concentration in the various stages was gradationally differentiated from the bottom to the top in the direction of medium flow. RNA content per unit cell concentration at each sage was determined. The cells in the lower stages were higher in RNA content than those from the upper stages. Wash out was observed to occur in the column at dilution rates which do not result in wash out in a single stage chemostat system.A study of the flow characteristics revealed that the overall performance of the plate column was equivalent to that of a multistage system, when hole diameter and hole area to column cross sectional area ratio were properly selected. This was true even in highly aerated conditions. These results indicated that the perforated plates in the column hindred intermixing through the plates, and that each stage functioned as an independent stirred vessel. Industrial and research application of this type fermentor was discussed.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260110516
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  • 22
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    A continuous, multistage tower fermentor. I. Design and performance tests (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 927-943 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The design of a continuous column fermentor with a multiple staging effect is described. The column is divided into four compartments by horizontal perforated plates and is provided with a central agitator shaft driving an impeller in each compartment. A tube at the center of each plate forms a liquid seal around the shaft and also acts as a “downcomer.”The fermentor is normally operated with counter-current flow of gas and medium. Fresh medium is added to the top stage and product is withdrawn from the bottom.The effect of plate and agitator design on fermentor performance was studied in terms of factor such as oxygen transfer rate, gas holdup, and interstage mixing. By proper choice of the design parameters, the fermentor was made to approximate a perfect four-stage cascade in terms of reactor performance.Preliminary experiments were performed with air-water systems, but a more realistic picture of fermentor performance was obtained in experience involving propagation of Escherichia coli. Data for business and substrate concentrations in each stage confirmed the staging effect of the apparatus. The fermentor operated in a stable manner for periods of more than two weeks.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260110517
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  • 23
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    The design and operation of high-power, magnetic drives (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 967-985 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A description is given of the design and operation of high-power magnetic drives developed to enable shaft seals and glands to be dispensed within deepculture vessels, in tissue homogenizers, and in mixing and filling processes where sterility is essential. The drives operate at speeds of 300 to 2000 rpm in volumes of 300 1. to 10 ml with clearances up to 16 mm between the pole faces of the magnets.Two types of drive are described, one in which the driving and driven magnets form an integral unit on the lid of a vessel: such vessels are used for transporting material. To intiate stirring, it is only necessary to connect a motor directly, or through a cable-drive, to the magnetic-drive assembly. In the other type of unit the driving magnet is attached permanently to the driving motor. Locating pins on the base of the motor and corresponding sockets on the lid of the vessel ensure that when the motor is in position, the driving and driven magnets are located correctly in relation to one another.The design of these drives is based on the use of multipole, ceramic magnets. The advantages of their use in such units, compared with metal magnets, are discussed. Earlier magnetic drives are also discussed and explanations offered for the difficulties formerly met in scaling up.
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    Design and physical characteristics of a multistage, continuous tower fermentor (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 945-966 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A multistage tower laboratory fermentor has been constructed consisting of eight compartments separated by sieve plates. Flow of substrate and air is concurrent from the bottom to the top of the column. It, was hoped that this system could be used to reproduce, simultaneously on a continuous basis, eight distinct phases of a batch growth curve. It was believed that the extent of batch curve simulation would depend upon the character of hydraulic mean residence time of broth in the column and in the individual compartments. The expected relationship did not occur. Rather it was found that growth in the column involved residence time characteristics not only for the fluid but also for the microorganisms, and for the growth limiting substrate. Depending upon the column operation, these could be distinct and different.The purpose of this investigation was to study the residence time distribution (RTD) of the continous (fluid) and dispersed (microorganisms) phases for model systems as well as for a yeast fermentation. Various degrees of flow nonideality, i.e., fluid blackflow and dispersed phase sedimentation, were noticed. The former seems to be due to interaction of the concurrent gas and liquid flow; it is particularly dependent upon void area of the sieve plate holes. Sedimentation is probably a function of plate design as well as cell size and density. It wa concluded that for a particular plate design the gas hold-up wass controlled by superficial air velocity and was the main parameter governing the differences between dispersed and continous phase(Rt1). This conclusion was supported by a computeraided styudy utilizing a mathematical model of fluid flow to fit the growth kinetics and cell distribution observed experimentally throughout the fermentor.Some advantages of foam control in the tower fermentor by surface active compounds are mentioned. Also, suggestions are made for carrying out fermentations that have two liquid phases, such as a hydrocarbon fermentation. The possibility of closely approximating plug-flow conditions in the multistage tower fermentor, a necessary condition for batch growth simulation, is discussed from a practical point of view.
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    A flow cell photometer for bacterial growth monitoring (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 1005-1010 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A flow cell photometer is described with automatic cleaning of the photometric cell, denasimetric separation of air bubbles and precipitates, and a constant sensitivity from 0 to 10 mg/ml of bacterial dry weight.
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    Recovery of biological materials through ultrafiltrationPresented at the 3rd International Fermentation Symposium, September 3-8, 1968, Rutgers University, New Brunswick, N.J. (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 987-1003 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experiments were performed on a cellulose acetate ultrafiltration membrane (HF-200, ABCOR Inc., Cambridge, Mass.) to test its efficacy in concentrating and purifying a crude enzyme (trypsin) preparation. Studies were also made to determine the influence of inorganic salts, pressure, and temperature on the rate of ultrafiltration for this membrane. The results showed reductions in the rates will be encountered due to the presence of inorganic salts. However, the reduced rates were still sufficiently high to make this method extremely attractive. Operating at filtration pressures above 75 psi at, 20 to 30°C for this membrane does not show any beneficial effect in terms of ultrafiltration rates. However, at 10°C there were continual increases in the filtration rates up to 100 psi. Concentration and purification studies with trypsin yielded a concentration factor of 8.35 and a purification factor 2.35. It was shown concretely that the purification of the enzyme was due to the passage of low molecular weight proteins (below 20,000) through the membrane. Enzyme activity slightly greater than 90% was obtained: 70% was found in the concentrate and 20% in the filtrate. It is concluded that membrane ultrafiltration is an ideal simple, rapid, and economical method for the recovery of biological active substances.
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    Automatic electrode selection device for monitoring ph (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 1027-1032 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
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    An improved, totally automated antibiotic bioassay machine (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 1011-1025 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A number of improvements have been made in a totally-automated antibiotic bioassay machine previously described. The new machine accepts unmeasured, untreated, opaque suspensions of fermentation beers three times faster (120 samples per hour) and supplies printed potencies sooner (in just over two hours). Whereas the original machine employed a self-cleaning filter and used disposable two milliliter beakers, this version involves a batch-dialysis scheme for effecting sample purification, and provides for automated cleaning of incubation chambers.In operation, a measured, portion of thoroughly-mixed fermentation beer is automatically diluted and transferred into one side of an incubation chamber, the two halves of which are separated by a dialysis membrane. The other half is filled with inoculated media. During the two hour incubation at 37°, dialyzable antibiotic limits growth of the inoculum in proportion to its concentration. After incubation, the turbidity of the inoculum is simultaneously read by an online computer and plotted on a strip chart recorded. The computer suplies printed potency values and sample identification on site, while the recording provides the operator with an analog record of turbidity. Fiber optics are employed in the turbidmetric readout, and an electric typewrite provides the printout.
    Additional Material: 18 Ill.
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    A simple 50-bottle fraction collector for volumes up to 350 litersResearch sponsored by National Institute of General Medical Sciences of the National Institutes of Health and by the U.S. Atomic Energy Commission under contract with the Union Carbide Corporation, Nuclear Division. (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 1033-1035 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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    Solubility of endotoxin and stability of its biological activity in organic liquids (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 1037-1041 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Tab.
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    Masthead (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260110601
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    Studies on methanol oxidizing bacteriaPaper presented at the conference of the International Organization of Biotechnology and Bioengineering (IOBB), May, 29th-30th, 1969, Stockholm. (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 1043-1054 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mixed culture of methanol oxidizing bacteria has been cultivated on simple inorganic salts medium supplemented with methanol. Optimal growth occurred at 31°C, pH 6.0-6.3, and a methanol concentration between 1 and 2 ml/1, of medium. The maximum yield was 4.5 g dw/I and the mean generation time 3.2 hr.It was estimated that 41% of methanol carbon was converted into cell-carbon, and that 73% of the inorganic nitrogen was converted to organic nitrogen.
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    Input and volume distributions for continuous cultures (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 10 (1968), S. 497-510 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An analysis is presented of the effects on substrate utilization and cell growth of varying the volume distribution of and the input distribution to a model continuous-culture unit consisting of three stirred tanks. The model is used to establish the best volume and input distributions and to indicate the effects of mixing imperfections. The Michaelis-Menten rate expression is utilized, including an endogenous respiration term, and results are presented on unique triaxial charts. Of the distributions considered, maximum substrate utilization is achieved with 60% of the total volume in the first stage, 20% in the second stage, and 20% in the third stage and with all of the input to the first stage. At a constant fractional input to the third stage; variation in the ratio of inputs to the first and second stages has virtually no effect, except in the case that a critical dilution is exceeded. At a constant input ratio to the first two stages, an increase in the fractional input to the third stage always decreases efficiency. Three stages, regardless of relative size, are always better than one. Except for endogenous respiration effects, cell growth parallels substrate utilization.
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    Foam concentration of streptokinase from crude culture filtrates (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 10 (1968), S. 551-552 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/bit.260100412
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    Automatic analysis of gas exchange in microbial systems (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 10 (1968), S. 535-549 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An automatically working test arrangement for the permanent analysis of O2 and CO2 in microbiological cultures is described. The measuring principle is based on the paramagnetic properties of oxygen and on the absorption of infrared by carbon dioxide. The preparation of the gas for measuring and the correction of the recording are indicated. The formula of correction was programmed and the values were calculated for a range of 3%. The routine correction of analysis values is done with a nomogram established on the basis of these individual values. The advantages of the described test arrangement are illustrated by two examples of growth experiments on Saccharomyces cerevisiae.
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    Effect of centrifugation on the viability of Burkitt lymphoma cellsContribution No. 1126 from the Department of Nutrition and Food Science, Massachusetts Institute of Technology. Presented at the 154th National Meeting of the American Chemical Society, Chicago, Illinois, September 10-15, 1967. (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 10 (1968), S. 641-649 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This study reports some findings on the effects of centrifugation on the viability of mammalian cells. The authors used Burkitt lymphoma cells cultivated in a synthetic medium containing 10% fetal calf serum for all experiments. Batch centrifugations were conducted in a RC2-B centrifuge (Ivan Sorvall, Incorporated, Norwalk, Connecticut USA) operated at 0 and 25°C. During centrifugation we exposed the cells to gravitational fields ranging from 24,800 to 42.200g. The results showed that at, 0°C and 25,800 or 42,000g no loss in cell viability occurred for up to 90 min exposures in the centrifugal field. However, at 25°C and for gravitational fields of 24,800 and 42,000g, there were appreciable losses in cell viability. Continuous centrifugation studies in the Sharples supercentrifuge (Division of Penn Salt Corporation, Warminister, Pennsylvania USA) were also conducted with bowl speeds up to 28,000 rpm (19,000g) and flow rates ranging from 1.4 to 20 1, hr. Slight, losses in cell viability were noted and postulated as caused by the shear stresses encountered by the cells. Some pumping studies using the lymphoma cells substantiate this conclusion.
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    New directions in the production of vaccines (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 10 (1968), S. 669-675 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: New trends and developments in vaccines emphasized the growing need for safety tests of increased complexity, rather than a need for ultrasophisticated and complex devices. The Vaccine Development Branch of the National Institute of Allergy and Infectious Diseases, operating with an annual budget of $6,000,000 has the task of expediting the collaborative efforts of 50 laboratories for developing, producing, and testing experimental vaccine lots. Rubella has a major priority; other priorities are assigned to respiratory syncytial, parainfluenza, adenoviruses, influenza, and rhinoviruses, and Mycoplasma pneumoniae. To accomplish this requires a very expensive and complex program involving rapid information exchange and increased emphasis on safety testing with regard to extraneous viruses and the oncogenic potential of the vaccines. The latter need resulted from such experience as that with the Salk vaccine and the tumorproducing potential of some adenoviruses. Electron microscopy has been useful in discovering possible viral contaminants. Of all material produced for experimental work, from 65 to 70% is used for safety tests.
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    A method for aeration and foam control in fermentation vessels (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 10 (1968), S. 677-680 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The production of large quantities of microbial mass, or their by-products, frequently requires aeration and mixing of fluid media. This operation often results in copious production of foam which cannot be exhausted with the effluent air or gas. Foam is usually controlled with antifoam agents which may interfere with product purity, oxygen uptake, and with subsequent product, handling. The process herein described obviates the requirement for antifoam agents or other foam-control methods. In essence, the air (or other gases) and foam in the headspace are continuously withdrawn, entrained in the intake side of a self-priming pump, and reintroduced into the bulk of the process liquid medium. The headspace may be enriched with oxygen or other gases.
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    A fraction collector for large-volume chromatograph separations (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 10 (1968), S. 681-683 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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    A new method for removal of inhibitory fermentation products (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 10 (1968), S. 689-692 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260100515
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    Equipment for the recovery of precipitates from tubular centrifuges (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 10 (1968), S. 684-688 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Equipment has been developed for the recovery of precipitates from rotors of industrial tubular centrifuges. A double piston is described for nonaseptic discharge of precipitates through the outlet holes of the clarifier rotor. For the aseptic resuspension or dissolving of valuable precipitates a closed-circulation system has been developed, which is applied without opening of the clarifier rotor.
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    Masthead (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 10 (1968) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260100601
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    A description and working recommendation for using a modified galvanic cell oxygen electrode (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 10 (1968), S. 693-697 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
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    Kinetics of gas diffusion in mammalian cell culture systems. I. Experimental (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 10 (1968), S. 725-740 
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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
    Notes: It has been demonstrated experimentally that the thickness of fluid overlay in conventional tissue culture systems limits the oxygen available to mammalian cells growing as a submerged monolayer. A rocker culture system is described which circumvents critical problems associated with thin film culture while permitting nearly unlimited access of oxygen to the cell monolayer. Good growth of primary hepatic cells as isolated sheets has been obtained.
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    Kinetics of microbial oxidation of n-heptane. I. Characterization of the process (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 417-426 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Utilization of n-heptane by a Pseudomonad was studied in pilot-size butch cultures. Optimal pH and temperature were determined by a factorial design and a medium based upon mineral uptake rates was formulated. High cell yields were obtained by volatilizing heptane in the incoming air and thereby achieving good hydrocarbon dispersion. Hydrocarbon carried by effluent gases was recovered and recycled. In cultures where pH is not controlled, decrease in the electrolytic conductivity of the medium was found to be indicative of viable cells and was used in monitoring bacterial propagation. If not checked, increase in salinity in pH controlled cultures was found to affect cell production negatively. Viscosity changes were not very significant. Heptane to aqueous medium ratio was found to affect oxygen supply to the system due to higher dissolved oxygen concentrations associated with hydrocarbons.
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    Enzymatic interesterification of triglyceride with surfactant-coated lipase in organic media (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 27-32 
    Details
    ISSN: 0006-3592
    Keywords: esterification ; lipase ; glycerides ; organic solvent ; surfactant ; bioconversion ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Several surfactant-coated enzymes have been prepared by coating lipases of various origins with a nonionic surfactant, glutamic acid dioleylester ribitol (2C18Δ9GE). Enzymatic interesterification of tripalmitin with oleic acid using the surfactant-coated lipase was carried out in organic media. The surfactant-coated lipases could effectively catalyze the interesterification of glycerides better than did the powder lipases. A suitable organic solvent was an aliphatic hydrocarbon such as isooctane. The enzymatic activity for the interesterification strongly depended on the origin of the lipase. The surfactant-coated lipase prepared by Mucor javanicus showed the highest enzymatic activity for the interesterification of glycerides, although its powder lipase did not show enzymatic activity. Selective interesterification of glycerides could be performed by adjusting the concentration ratio of oleic acid to tripalmitin in isooctane. Di-substituted glyceride could be selectively produced when the concentration ratio of carboxylic acid to glycerides was 7. © 1995 John Wiley & Sons, Inc.
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    On-line gas analysis in animal cell cultivation: II. Methods for oxygen uptake rate estimation and its application to controlled feeding of glutamine (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 54-62 
    Details
    ISSN: 0006-3592
    Keywords: oxygen uptake rate ; animal cell cultivation ; hybridoma ; monoclonal antibody ; glutamine ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Different methods for oxygen uptake rate (OUR) determinations in animal cell cultivation were investigated using a high quality mass spectrometer. Dynamic measurements have considerable disadvantages because of disturbances of the growing cells by the necessary variations of dissolved oxygen concentration. Only infrequent discrete measurements are possible using this method. Stationary liquid phase balance yielded better results with much higher frequency. Gas phase balancing has the advantage of not requiring dissolved oxygen measurement and knowledge of KLa, both of them are easily biased. It was found that simple gas phase balancing is either very inaccurate (error larger than expected signal) or very slow, with gas phase residence times of several hours. Therefore, a new method of aeration was designed. Oxygen and CO2 transfer are mainly achieved via sparging. The gas released to the headspace is diluted with a roughly 100-fold stream of an inert gas (helium). Through this dilution, gas ratios are not changed for O2, CO2, Ar, and N2. The measurement of lower concentrations (parts per million and below) is easy using mass spectrometry with a secondary electron multiplier. With this new method an excellent accuracy and sufficient speed of analysis were obtained. All these on-line methods for OUR measurement were tested during the cultivation of animal cells. The new method allowed better study of the kinetics of animal cell cultures as was shown with a hybridoma cell line (HFN 7.1, ATCC CRL 1606) producing monoclonal antibodies against human fibronectin. With the aid of these methods it was possible to find a correlation between a rapid decrease in oxygen uptake rate (OUR) and glutamine concentration. The sudden decrease in OUR can be attributed to glutamine depletion. This provided a basis for the controlled addition of glutamine to reduce the formation of ammonia produced by hydrolysis. This control method based on OUR measurement resulted in increased cell concentration and threefold higher product concentration. © 1995 John Wiley & Sons, Inc.
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    The Monod equation and mass transfer (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 91-94 
    Details
    ISSN: 0006-3592
    Keywords: mass transfer ; Monod equation ; growth rate ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An alternative interpretation of the growth rate-substrate concentration dependence is presented. This is based on the assumption that the main factors affecting growth rate are transfer of substrate from the medium and the maximum growth velocity, which is that observed when no substrate limitations occur. This approach allows the approximate prediction of one of the two kinetic constants required, and may be of great use, especially for continuous cultures. It is the first attempt to provide a phenomenological explanation for the large variations observed in the values of the Monod constant, Ks, reported in the literature. © 1995 John Wiley & Sons, Inc.
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    Influence of cell- and media-derived factors on the integrity of a human monoclonal antibody after secretion into serum-free cell culture supernatants (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 97-106 
    Details
    ISSN: 0006-3592
    Keywords: antibody integrity ; human monoclonal antibodies ; insect cells ; mammalian cell culture ; proteolytic activity ; protein microheterogeneity ; serum-free media ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To investigate the effects of factors secreted by different cell lines on human monoclonal antibody (MAb) integrity, 600 mg of a human MAb, which specifically binds to human erythrocytes, were produced in a perfusion process. After purification by protein A affinity chromatography, the MAb was used for integrity testing in supernatants of several cell lines to investigate their potential to degrade the antibody in the extracellular environment. One insect cell line (IPLB-SF-21 AE) and four mammalian cell lines [CHO K1, BHK-21 (C13), C1271, P3-X63-Ag8.653], all of them commonly used for the production of recombinant proteins, and the human-human-mouse heterohybridoma cell line itself (H-CB-hahE), were adapted to serum-free culture media. For integrity testing all cell lines were cultivated in spinner flasks using serum-free media supplemented with 30 μg mL-1 of purified MAb. MAb integrity was assayed by SDS polyacrylamide gel electrophoresis (SDS-PAGE), isoelectric focusing, both followed by Western blotting, and an antigen binding assay. None of the mammalian cells showed any detectable effects on antibody stability and integrity during exponential growth, whereas isoelectric focusing of monoclonal antibody taken from IPLB-SF-21 AE culture supernatants revealed a new band indicating a partial modification of the MAb by secreted factors of these cells. This observation did not correlate with the total proteolytic activity, which was measured in all supernatants and found to be lowest in the insest cell cultures. For mammalian cell cultures, it could be concluded from these findings that shifts of the antibody microheterogeneity pattern, which can be found normally as a result of variations in different production parameters, are not caused by extracellular factors once the product has been secreted into the supernatant. In addition to their well-known advantages in posttranslational modifications (e.g., formation of complex type N-glycans), mammalian cells appear to be more suitable as expression systems for human monoclonal antibodies to be used in vivo when compared with baculovirus-infected insect cells. © 1995 John Wiley & Sons, Inc.
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    On-line calibration of a computerized biosensor system for continuous measurements of glucose and lactate (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 122-128 
    Details
    ISSN: 0006-3592
    Keywords: on-line calibration ; continuous monitoring ; biosensor system ; enzyme reactor ; glucose ; lactate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An on-line calibration procedure for application in continuous monitoring systems has been developed. Control of the calibration value and recalibration on-line during monitoring is possible without having to disrupt the sample withdrawal. The calibration procedure has been applied and evaluated in a continuous biosensor system based on the detection of oxygen depletion during enzymatic substrate conversion by immobilized oxidases. Evaluation included on-line calibration during continuous measurements of glucose and lactate in bovine blood samples. Calibration of the complete system consisting of a sampling device, a sample handling step, a biocatalytic step, a detection step, and a data processing unit is performed by the on-line addition of a calibration solution to a blank sample which is fed through the system. The calibration cycle is completed within 5.5 min. When recalibration is carried out during monitoring, the calibration solution is added to the sample, instead of to a blank sample, and the increase in outlet singl is registered. The major advantage of this internal standard principle is that the calibration solution is fed through the whole system according to the same path as the sample solution and thus takes into account all parameters influencing the sample. © 1995 John Wiley & Sons, Inc.
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    Modeling of anaerobic formate kinetics in mixed biofilm culture using dynamic membrane mass spectrometric measurement (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 219-228 
    Details
    ISSN: 0006-3592
    Keywords: formate conversion ; mass spectrometer ; anaerobic conversion ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The dynamics of the anaerobic conversion of formate in a microbial mixed culture taken from an anaerobic fluidized bed reactor was studied using a new stirred micro reactor equipped with a membrane mass spectrometer. The microreactor with a toroidally shaped bottom and pitched blade turbine and a cylindrical flow guide was thermostated and additionally equipped with a pH electrode and pH control. During fed-batch experiments using formate, the dissolved gases (methane, hydrogen, and carbon dioxide), as well as the acid consumption rates for pH control were monitored continuously. Initially and at the end of each experiment, organic acids were analyzed using ion chromatography (IC). It was found that about 50% of the formate was converted to methane via hydrogen and carbon dioxide, 40% gave methane either directly or via acetate. This was calculated from experiments using H13CO3- pulses and measurement of 12CH4 and 13CH4 production rates. About 10% of the formate was converted to lactate, acetate, and propionate, thereby increasing the measured CO2/CH4 production ratio. The nondissociated formic acid was shown to be rate determining. From the relatively high Ks value of 2.5 mmol m-3, it was concluded that formate cannot play an important role in electron transfer. During dynamic feeding of formate, hydrogen concentration always increased to a maximum before decreasing again. This peak was found to be very discriminative during modeling. From the various models set up, only those with two-stage degradation and double Monod kinetics, both for CO2 and hydrogen, were able to describe the experimental data adequately. Additional discrimination was possible with the IC measurement of organic acids. © 1995 John Wiley & Sons, Inc.
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    Effect of surfactant and particle size reduction on hydrolysis of deinking sludge and nonrecyclable newsprint (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 239-244 
    Details
    ISSN: 0006-3592
    Keywords: cellulase ; newsprint ; deinking sludge ; surfactant ; hydrolysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Disposal of sludge from deinking mills represents a significant proportion of operating costs. Bioconversion of the cellulosic fraction of deinking sludge (DIS) to ethanol greatly reduces disposal costs while producing an environmentally friendly fuel. In this study, the cellulosic fraction of newsprint and deinking sludge was hydrolysed to produce fermentable sugars. For newsprint, a particle size of 1 to 1.5 mm provided optimal reaction rates in batch reactors over practical hydrolysis times, and reducing sugar concentrations as high as 35 g/L could be achieved using a fed-batch reactor configuration. For both newsprint and DIS, the hydrolysis rate increased nonlinearly with enzyme loading. Tween-80 only marginally improved sugar production but was able to release sugars from cellulosic substrates in the absence of lytic enzymes, in an amount proportional to the surfactant concentration and the substrate particle size. DIS was relatively recalcitrant to enzymatic hydrolysis, possibly due in part to inhibition by hydrophobic constituents. © 1995 John Wiley & Sons, Inc.
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    Photolithotrophic cultivation of Laminaria saccharina gametophyte cells in a stirred-tank bioreactor (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 251-260 
    Details
    ISSN: 0006-3592
    Keywords: macroalgal cells ; stirred-tank bioreactor ; photolithotrophic cultivation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Filamentous cell cultures derived from female gametophytes of the temperate brown macroalga Laminaria saccharina were photolithotrophically cultivated in artificial seawater medium within an illuminated 1.3-L stirred-tank bioreactor at 13°C using CO2 in air as the carbon source. A Monod model adequately described light-saturated growth. The apparent half-saturation constant (Ko) was 23 μE/m2-s, and maximum specific growth rate was 0.15 day-1. At a constant inoculation cell density of 50 mg DCW/L, biomass productivity after 26 days of cultivation increased from 630 mg DCW/L at 18 μE/m2-s to 890 mg DCW/L at 228 μE/m2-s. At 98 μE/m2-s, 1.1 vvm aeration rate, and 250 rpm impeller speed, the CO2 transfer rates (CO2 TRs) and CO2 consumption rates (rco2) were determined over the cultivation period. At peak CO2 demand, the maximum CO2 TR was 0.19 mmol CO2/L-h, but rco2 was only 0.15 mmol CO2/L-h, implying that the culture was not CO2 transport limited. This is the first reported bioreactor cultivation study of cell cultures derived from a macrophytic marine alga. © 1995 John Wiley & Sons, Inc.
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    Masthead (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260450401
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    Removal of phenols and aromatic amines from wastewater by a combination treatment with tyrosinase and a coagulant (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 304-309 
    Details
    ISSN: 0006-3592
    Keywords: phenol ; substituted phenol ; tyrosinase ; immobilization ; chitosan ; coagulant ; immobilized enzyme ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Removal of phenols and aromatic amines from industrial wastewater by tyrosinase was investigated. A color change from colorless to darkbrown was observed, but no precipitate was formed. Colored products were found to be easily removed by a combination treatment with tyrosinase and a cationic polymer coagulant containing amino group, such as hexamethylenediamine-epichlorohidrin polycondensate, polyethleneimine, or chitosan. The first two coagulants, synthetic polymers, were more effective than chitosan, a polymer produced in crustacean shells. Phenols and aromatic amines are not precipitated by any kind of coagulants, but their enzymatic reaction products are easily precipitated by a cationic polymer coagulant. These results indicate that the combination of tyrosinase and a cationic polymer coagulant is effective in removing carcinogenic phenols and aromatic amines from an aqueous solution. Immobilization of tyrosinase on magnetite gave a good retention of activity (80%) and storage stability i.e., only 5% loss after 15 days of storage at ambient temperature. In the treatment of immobilized tyrosinase, colored enzymatic reaction products were removed by less coagulant compared with soluble tyrosinase. © 1995 John Wiley & Sons, Inc.
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    Dielectrophoretic separation of cells: Continuous separation (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 337-343 
    Details
    ISSN: 0006-3592
    Keywords: dielectrophoresis ; cells, separation of ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dielectrophoresis is the movement of particles in non-uniform alternating and direct current (AC, DC) electric fields. When nonuniform electric fields are created between microelectrodes, cells will redistribute themselves around the electrodes, the force holding the cells in place dependig on the local electric field and on the electrical properties of the cells themselves and the suspending medium. Steric drag forces produced by a gentle fluid flow in the chamber can be used to separate cells by selectively lifting cells from potential energy wells produced by the electric field. The technique is demonstrated in the batch separation of bacteria, yeast cells, and plant cells. Continuous separation and extraction of two cell types can be achieved by repeated reversing of the fluid flow direction in phase with the switching on and off of the applied voltage, and the efficacy of the technique is demonstrated for viable and nonviable (heat-treated) yeast cells. © 1995 John Wiley & Sons, Inc.
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    Esterification reactions catalyzed by Chromobacterium viscosum lipase in CTAB-based microemulsion systems (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 344-355 
    Details
    ISSN: 0006-3592
    Keywords: esterification ; Chromobacterium viscosum ; lipase ; microemulsions ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Chromobacterium viscosum (CV) lipase solubilized in water-in-oil (w/o) microemulsions based on the cationic surfactant hexadecyltrimethylammonium bromide (CTAB) have been used for multigram-scale ester synthesis, including the kinetic resolution of a secondary alcohol. The stability of CV lipase in all the CTAB microemulsions studied was excellent and was superior to that observed in aqueous buffer at the same pH and temperature. Kinetic studies were performed using the synthesis of ethylhexadecanoate as a model reaction. Under pseudo-first-order conditions, the synthesis rates were linearlydependent on the enzyme and fatty acid concentrations and the R dependence shows the characteristic bell-shaped curve (where R = [H2O]/[surfactant]). The dependence of enzyme activity toward octyldecanoate synthesis on the pH of the dispersed buffer phase is in marked contrast to that observed for the pH dependence of CV lipase toward p-nitrophenylbutyrate hydrolysis. In the former case, the pH-activity profile is approximately sigmoidal, which may reflect the ionization state of the fatty acid substrate. In the latter case, the pH dependence is minimal at both R = 10 and R = 50, suggesting the enzyme does not experience a changed pH environment. Inclusion of a pH-sensitive probe molecule into those incubations containing fatty acid clearly demonstrates that the probe molecule experiences a changed environment consistent with that expected for the selected buffer. An in situ Fourier transform nuclear magnetic resonance (FT-NMR) assay has been developed which allows continuous monitoring of the esterification reactions, thereby providing an additional means of determining initial rates. The method may be of general value for lipase assays in microemulsions since it may provide, at the same time, information regarding enzyme regioselectivity. © 1995 John Wiley & Sons, Inc.
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    Masthead (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260460201
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    Correlation between steady-state cell concentration and cell death of hybridoma cultures in chemostat (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 18-26 
    Details
    ISSN: 0006-3592
    Keywords: hybridoma ; cell death ; chemostat ; autoinhibitor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the present study, the steady-state cell density (X) of chemostat cultures of murine hybridoma was varied by the concentration of glucose and glutamine in culture medium and the dissolved oxygen partial pressure. Except at low glutamine and low oxygen levels, the specific death rate (kd) of the cultures was found to decrease with increasing dilution rate (D). However, the plot of kd vs. X/D yielded linear relation, which suggests that cell death was due to a non-growth-linked inhibitory product of the cells. The kd value measured at low glutamine and low oxygen levels remained practically unchanged over a wide range of D between 0.020 and 0.029 h-1. The kd for low oxygen cultures was always lower than the values obtained in low glucose and low glutamine cultures. A low-molecular-weight component of possibly less than 3000 MW was detected to be cell-death-inducing in the supernatant of exponentially growing cultures. It was neither lactate nor ammonium. The autoinhibitor was not cell-line specific. © 1995 John Wiley & Sons, Inc.
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    An in situ dissolved-hydrogen probe for monitoring anaerobic digesters under overload conditions (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 63-68 
    Details
    ISSN: 0006-3592
    Keywords: dissolved-hydrogen probe ; anaerobic digestion ; hydrogen ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The concentration of diatomic hydrogen in the liquid phase of an anaerobic digester was used to determine the onset of digester failure induced by substrate overloading. The construction of an inexpensive probe to measure dissolved hydrogen, having a partial pressure detection limit of 30 Pa, is described. An increase in the partial pressure of dissolved hydrogen, from less than 30 Pa to 400 Pa, was observed when the D-glucose concentration in a laboratory-scaled digester was increased rapidly to 10 mM. However, when the digester was gradually overloaded, an increase in the dissolved-hydrogen partial pressure was not observed until after the digester failed. The accumulation of volatile fatty acids and digester failure were observed at dissolved-hydrogen partial pressures below 30 Pa. © 1995 John Wiley & Sons, Inc.
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    Starvation-induced programmed death of hybridoma cells: Prevention by amino acid mixtures (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 86-90 
    Details
    ISSN: 0006-3592
    Keywords: hybridoma ; nutrition ; cell death ; apoptosis ; monoclonal antibody ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Association of the availability of nutrients with the phenomenon of programmed cell death - apoptosis - was investigated using hybridoma cells cultured in protein-free medium under conditions of starvation, i.e., in RPMl-1640 medium diluted to 50% with saline. Amino acid mixtures, such as MEM essential amino acids or MEM nonessential amino acids were found to prevent starvation death significantly when added to the diluted medium in 1 to 2 mM concentrations, the MEM vitamin mixture was ineffective, and glutamine displayed a moderate growth-supporting effect. The specific monoclonal antibody production rate in cultures supplemented with amino acid mixtures was strikingly low, whereas supplementation with glutamine alone or simultaneously with other amino acids resulted in a specific antibody production rate comparable with the rate observed in undiluted medium. © 1995 John Wiley & Sons, Inc.
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    Masthead (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260460401
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    A kinetic model for product formation of microbial and mammalian cells (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 314-324 
    Details
    ISSN: 0006-3592
    Keywords: product formation ; kinetic model ; microbial cells ; mammalian cells ; substrate excess ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Growth of microbial and mammalian cells can be classified into substrate-limited and substrate-sufficient growth according to the relative availability of the substrate (carbon and energy source) and other nutrients. It has been observed for a number of microbial and mammalian cells that the consumption rate of substrate and energy (ATP) is generally higher under substratesufficient conditions than under substrate limitation. Accordingly, the product formation under substrate excess often exhibits different patterns from those under substrate limitation. The extent of increase or decrease in product formation may depend not only on the nature of limitation and cell growth rate but also on the residual substrate concentration in a relatively wide range. The product formation kinetic models existing in literature cannot describe these effects. In this study, the Luedeking-Piret kinetic is extended to include a term describing the effect of residual substrate concentration. The extended model has a similar structure to the kinetic model for substrate and energy consumption rate recently proposed by Zeng and Deckwer. The applicability of the extended model is demonstrated with three microbial cultures for the production of primary metabolites and three hybridoma cell cultures for the production of ammonia and lactic acid over a wide range of substrate concentration. The model describes the product formation in all these cultures satisfactorily. Using this model, the range of residual substrate concentration, in which the product formation is affected, can be quantitatively assessed. © 1995 John Wiley & Sons, Inc.
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    Citric acid production by Candida lipolytica Y 1095 in cell recycle and fed-batch fermentors (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 325-332 
    Details
    ISSN: 0006-3592
    Keywords: cell recycle ; fed-batch ; oxygen uptake ; dissolved oxygen ; Candida lipolytica ; citric acid ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of dissolved oxygen on citric acid production and oxygen uptake by Candida lipolytica Y 1095 was evaluated in cell recycle and fed-batch fermentation systems. The maximum observed volumetric productivity, which occurred at a dilution rate of 0.06 h-1, a dissolved oxygen concentration of 80%, and a biomass concentration of 5% w/v, in the cell recycle system, was 1.32 g citric acid/L · h. At these same conditions, the citric acid yield was 0.65 g/g and the specific citric acid productivity was 24.9 mg citric acid/g cell · h. In the cell recycle system, citric acid yields ranged from 0.45 to 0.72 g/g. Both the volumetric and specific citric acid productivities were dependent on the dilution rate and the concentration of dissolved oxygen in the fermentor. Similar productivities (1.29 g citric acid/L · h) were obtained in the fed-batch system operated at a cycle time of 36 h, a dissolved oxygen concentration of 80%, and 60 g total biomass. Citric acid yields in the fed-batch fermentor were consistently lower than those obtained in the cell recycle system and ranged from 0.40 to 0.59 g/g. Although citric acid yields in the fed-batch fermentor were lower than those obtained in the cell recycle system, higher citric:isocitric acid ratios were obtained in the fed-batch fermentor. As in the cell recycle system, both the volumetric and specific citric acid productivities in the fed-batch fermentor were dependent on the cycle time and dissolved oxygen concentration. © 1995 John Wiley & Sons, Inc.
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    Cell cycle and cell size dependence of susceptibility to hydrodynamic forces (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 88-92 
    Details
    ISSN: 0006-3592
    Keywords: cell cycle ; hydrodynamic forces ; apoptosis ; cell culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Exposure of animal cells to intense hydrodynamic forces exerted in turbulent capillary flow, and by controiled agitation and aeration, resulted in preferential destruction of S and G2 cells and the extent of destruction of these cells was dependent upon the intensity of the action. The loss of these cells was possibly due to their larger size. However, the appearance of large numbers of membrane-bound vesicular structures similar to apoptotic bodies as well as cells with low DNA stainability (in a sub-G1 peak) suggested that the action of adverse hydrodynamic forces on these large cells may at least in part be to induce an apoptotic response. © 1995 John Wiley & Sons, Inc.
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    Photochemistry of a photosynthetic reaction center immobilized in lipidic cubic phases (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 93-98 
    Details
    ISSN: 0006-3592
    Keywords: photosynthetic reaction center ; liquid crystals ; cubic phases ; immobilization ; Chloroflexus aurantiacus ; photochemistry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Photosynthetic reaction centers, isolated and purified from the facultative phototrophic bacterium Chloroflexus aurantiacus, were immobilized in optically transparent lipidic cubic phases composed of 42% (w/w) 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine and 58% (w/w) water. The immobilized photosynthetic protein retains its native properties, as indicated by visible and circular dichroic spectra. The ground state visible spectrum of the immobilized reaction centers is very similar to the corresponding spectrum in aqueous solution, indicating that the protein pigments are not extracted into the lipidic regions of the cubic phase. The secondary structure of the protein is maintained in the immobilized state, as determined by far-UV circular dichroism spectroscopy in the 200- to 250-nm range. Moreover, immobilized reaction centers retain their photochemical activity: a reversible photo-oxidation of the primary electron donor (P) is seen upon continuous illumination. Furthermore, the entrappment of reaction centers does not affect the kinetics of charge recombination between the photo-oxidized primary donor (P+) and the photoreduced primary quinone acceptor, generated by a short flash of light. Reaction centers devoided of the secondary quinone acceptor can be easily reconstituted in cubic phases by means of their coimmobilization with 1,4-naphtoquinone. Indeed, the kinetics for charge recombination in reconstituted reaction centers is dramatically slower than the corresponding kinetics in the unreconstituted protein. Interestingly, immobilized reaction centers are significantly stabilized as compared with reaction centers in aqueous solution: the integrity of the protein in the cubic phase is maintained for at least 5 months, whereas in water solution 50% of the activity is lost within 2 months. © 1995 John Wiley & Sons, Inc.
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    Metabolic flux distributions in Penicillium chrysogenum during fed-batch cultivations (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 117-131 
    Details
    ISSN: 0006-3592
    Keywords: biochemical model ; Penicillium chrysogenum ; flux analysis ; penicillin ; metabolic engineering ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Based on a review of the Penicillium chrysogenum biochemistry a stoichiometric model has been set up. The model considers 61 internal fluxes and there are 49 intracellular metabolites which are assumed to be in pseudo-steady state. In addition to the intracellular fluxes the model considers the uptake of 21 amino acids. From the stoichiometric model the maximum theoretical yield of penicillin V is calculated to 0.43 mol/mol glucose. If biosynthesis of cysteine is by direct sulfhydrylation rather than by transsulfuration, the maximum theoretical yield is about 20% higher, i.e., 0.50 mol/mol glucose. The theoretical yield decreases substantially if α-aminoadipate is converted to 6-oxo-piperidine-2-carboxylic acid (OPC). If only 40% of the α-aminoadipate is recycled, the maximum theoretical yield is 0.31 mol/mol glucose. The uptake rates of glucose, lactate, γ-aminobutyrate, and 21 amino acids were measured during fed-batch cultivations. The rates of formation of penicillin V, δ-(L-α)-aminoadipyl-L-cysteinyl-D-valine (ACV), OPC, and the pool of isopenicillin N, 6-APA, and 8-HPA were also measured. Finally the synthesis rates of the biomass constituents RNA/DNA, protein, lipid, carbohydrate, and amino carbohydrate were measured. From these measured rates and the stoichiometric model the metabolic fluxes through the different intracellular pathways are calculated. The calculations show that penicillin formation is accompanied by a large flux through the pentose phosphate (PP) pathway due to a large requirement for nicotinamide-adenine dinucleotide phosphate (NADPH) used in the biosynthesis of cysteine. If cysteine is added to the medium, the flux through the PP pathway decreases. From the stoichiometric model YxATP is calculated to 87 mmol adenosine triphosphate (ATP)/g dry weight (DW), and from the flux calculations mATP is found to 3 mmol ATP/g DW/h. © 1995 John Wiley & Sons, Inc.
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    Reversed micellar extraction of trypsin: Effect of solvent on the protein transfer and activity recovery (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 172-174 
    Details
    ISSN: 0006-3592
    Keywords: reversed micelles ; extraction ; trypsin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: By using trypsin as the model protein and AOT as the model surfactant, the effect of a variety of solvents on protein transfer and activity recovery during the liquid-liquid reversed micellar extraction was investigated. It was found that several solvents, including isooctane, octane, heptane, and kerosene, had a similar effect on the recovery of trypsin activity after a full cycle of forward and backward extraction, and could all be used as the solvents for AOT-reversed micelles in trypsin extraction. Two other solvents (hexane and cyclohexane), however, were not so efficient. © 1995 John Wiley & Sons, Inc.
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    Relationship between loss of heavy chains and the appearance of nonproducing hybridomas (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 270-275 
    Details
    ISSN: 0006-3592
    Keywords: hybridoma ; antibody ; heavy chain ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: One drawback to the in vitro production of monoclonal antibodies is the loss of productivity exhibited by hybridomas over time, which has been shown to correspond to the appearance of a nonproducing subpopulation. In this study, we monitored the presence of antibody components, both intra- and extracellular, between producing and nonproducing hybridomas. A nonproducing cell population appeared which lacked heavy chain, while all cultures continued to produce light chain, indicating that the loss in antibody production resulted from the absence of heavy chain and occurred before protein assembly or secretion. © 1995 John Wiley & Sons, Inc.
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    Affinity purification of proteins using ligands derived from peptide libraries (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 288-297 
    Details
    ISSN: 0006-3592
    Keywords: protein purification ; peptide libraries ; ligands ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Peptide libraries can be used to identify ligands that bind specifically to a desired protein. These peptides may have significant advantages as specific ligands for affinity chromatography separations. This article describes the use of one of such peptide, Try-Asn-Phe-Glu-Val-Leu, as a ligand for the purification of S-protein using affinity chromatography. General strategies for peptide immobilization are discussed and the conditions for peptide immobilization to Emphaze™ gel are optimized. The effects of peptide orientation and peptide densities on protein binding are studied. Results indicate that the peptide affinity is not affected by the orientation of the peptide during immobilization, but association constants can be reduced by one order of magnitude when compared with the values in solution.With increased peptide density, the protein binding capacity of the gel increases, but both the percentage of peptide utilization and apparent binding constant between immobilized peptide and S-protein decrease. S-protein is separated from a mixture with BSA via affinity chromatography using specific elution with the peptide in solution.Finally, direct purification of S-protein from an enzymatic digestion mixture of ribonuclease A is demonstrated.© 1995 John Wiley & Sons, Inc
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    A structured metabolic model for anaerobic and aerobic stoichiometry and kinetics of the biological phosphorus removal process (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 277-287 
    Details
    ISSN: 0006-3592
    Keywords: phosphorus removal ; biological ; kinetics ; metabolic model ; polyphosphate ; PHB ; glycogen ; batch reactor, sequenced ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A structured metabolic model is developed that describes the stoichiometry and kinetics of the biological P removal process. In this approach all relevant metabolic reactions underlying the metabolism, considering also components like adenosine triphosphate (ATP) and nic-otinamide-adenine dinucleotide (NADH2) are describedbased on biochemical pathways. As a consequence of the relations between the stoichiometry of the metabolic reactions and the reaction rates of components, the required number of kinetic relations to describe the process is reduced. The model describes the dynamics of the storage compounds which are considered separately from the active biomass. The model was validated in experiments at a constant sludge retention time of 8 days, over the anaerobic and aerobic phases in which the external oncentrations as well as the internal fractions of the relevant components involved in the P-removal process were monitored. These measurements include dissolved acetate, phosphate, and ammonium; oxygen consumption; poly-β-hydroxybutyrate (PHB); glycogen; and active biomass. The model satisfactorily describes the dynamic behavior of all components during the anaerobicand aerobic phases.© 1995 John Wiley & Sons, Inc
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    In-situ removal of ammonium and lactate through electrical means for hybridoma cultures (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 308-318 
    Details
    ISSN: 0006-3592
    Keywords: hybridoma ; cell growth ; antibody production ; toxic waste removal ; electrical technique ; electrokinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ammonium and lactate are two known toxic products detrimental to mammalian cell growth and productivity. An electrokinetic technique, utilizing an electrophoretic mechanism, was developed to remove these cellular wastes in-situ from suspension hybridoma (ATCC CRL-1606) cultures to enhance cell growth and productivity. This technique applies continuously a dc electric field to selectively remove the electrically charged wastes. The experiments were shown to be successful in the removal of externally added 10 rnM ammonium and 45 mM lactate while maintaining the chemostatic condition of culture medium in a cell-free condition under an electric current density of 50 A/m2. Toxic levels of ammonium were added, ranging from 7.5 to 12.5 mM, at the start of the hybridoma culture, and the applied dc electric fields were able to completely remove these added materials. This in turn released the inhibition and restored the cell growth. Finally, this electrokinetic technique was applied to the batch and glutamine fed-batch hybridoma cultures. At an applied electric current density of 50 A/m2, this was able to completely remove cell-produced ammonium and increased the cell growth and antibody titer by 30% to 50%, respectively, compared to the control experiment in the absence of the electric field. Lastly, the applied electric current density of 50 A/m2 did not affect cellular functionalities such as glucose and glutamine consumption and antibody productivity.© 1995 John Wiley & Sons, Inc
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    High-rate continuous biodegradation of concentrated chlorinated aliphatics by a durable enrichment of methanogenic origin under carrier-dependent conditionsDedicated to the memory of Jean-Baptiste Boucquey (1970-1994). (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 298-307 
    Details
    ISSN: 0006-3592
    Keywords: anaerobic biodegradation ; polychlorinated aliphatics ; acclimation ; enrichment ; polyurethaneactivated carbon carrier ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The simultaneous biodegradation of toxic compounds in mixtures is a major current concern. To bioremediate a toxic mixture, we designed a strategy combining an ad-sorbent carrier with an ecological and nutritional system which allowed work close to heavily polluted conditions in nature. Starting from a methanogenic community, we developed a microbial consortium acclimated to a mixture of about 30 chlorinated aliphatics in a fixed-film stationary-bed bioreactor. Prior to the establishment of a durable period of dechlorination, an interval of progressive dechlorination of the toxic mixture was observed during which the excess of the toxic compounds was stored on the carrier. The latter, consisting of activated carbon in a polyurethane foam, allowed us to work at concentrations far above the solubility of the toxic compounds (apparent concentrations of about 10 g/L). The complete disappearance of hexachloroethane as well as its lower homologues, penta-, tetra-, and trichloroethane, present in the toxic mixture, was observed. Additionally, octachlorocyclopentene, carbon tetrachloride, trichloro-ethylene, tetrachloroethylene, and hexachloro-1,3-butadiene also completely disappeared. For the four latter compounds, from mass balances in the bioreactor, degradation rates around 10 μmol/L per day were determined with total dechlorination. The enrichment culture thus developed exhibited high degradation performances similar to those reported in the literature for pure or enriched anaerobic microbial cultures in contact with a single toxic compound. The results demonstrate the possibility of concurrent high-rate degradation of several highly chlorinated toxic compounds, under conditions approximating field situations.© 1995 John Wiley & Sons, Inc
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    Effect of different cell culture conditions on the polypeptide integrity and N-glycosylation of a recombinant model glycoprotein (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 536-544 
    Details
    ISSN: 0006-3592
    Keywords: protein glycosylation ; recombinant proteins ; process control ; product integrity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of different short-term controlled cell culture conditions on the product quality of a genetically engineered human interleukin-2 N-glycosylation variant protein expressed from a baby hamster kidney cell line (BHK-21) has been investigated. A perfused 2-L stirred tank reactor was used. Products purified from the culture supernatant of cells grown under experimentally initiated nutrient limitations (glucose, amino acids, pO2) were characterized by their HPLC-elution profile, SDS-PAGE and western blotting, amino acid sequencing as well as for their N-linked carbohydrates, using “HPAEC-PAD fingerprinting” and methylation analysis. The glycoprotein products secreted from cells under the different culture conditions (kept for 24 h, after an adaption time period of 48 h) showed an almost identical oligosaccharide pattern. By contrast, short-term changes of the culture condition led to considerable differences in the ratio of glycosylated to unglycosylated protein forms. Significant amounts of NH2-terminally truncated polypeptide forms were observed. They lacked proponderantly the first two amino acids; however, under certain culture conditions forms lacking up to eight NH2-terminal amino acids were detected. © 1995 John Wiley & Sons, Inc.
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    Kinetics of nitrate inhibition of carbon tetrachloride transformation by a denitrifying consortia (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 279-284 
    Details
    ISSN: 0006-3592
    Keywords: carbon tetrachloride ; nitrate inhibition ; biodegradation ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of nitrate inhibition of carbon tetrachloride (CT) transformation were examined using a denitrifying consortium. Comparison of data from fed-batch experiments to the model reported by Hooker et al. indicate that the inhibition constant ranges between 3.2 and 21 mg/L, with an average of 8.8 mg/L. This range is much lower than the previously reported value of 169 mg/L. Simulations using the corrected parameter accurately reflect this new data and the data reported by Hooker et al. In contrast, the earlier reported coefficient value does not reflect the data reported in this work. © 1995 John Wiley & Sons, Inc.
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    Development of optimized transfectoma cell lines for production of chimeric antibodies in hollow fiber cell culture systems (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 310-319 
    Details
    ISSN: 0006-3592
    Keywords: chimeric antibodies ; transfectoma cells ; hollow fiber fermentor ; immunoglobulin enhancer ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Methods for the selection of transfectoma cells that express large quantities of mouse-human chimeric antibodies have been develped. SP2/0 mouse myeloma cells were transfected with pSV2-gpt and pSV2-neo based immunoglobulin expression vectors. Double transfectants were selected using the xanthine-guanine phosphoribosyl transferase (gpt)and the neomycin (neo) selection marker genes. ELISA-based screening of transfectoma clones resulted in the isolation of IgG-producing transfectomas. Introduction of the kappa light-chain 3′-enhancer into the light-chain expression vector significantly increased immunoglobulin expression, but only when the enhancer was located at its physiological site, 9 kb downstream of the kappa constant region exon. With some of the transfectomas, final yields of up to 80 mg/L of chimeric IgG were obtained in conventional flask cultures using serum-free growth medium. A pilot-scale AcuSyst Maximizer hollow fiber cell culture system was used for the production of gram amounts of chimeric IgG. Results obtained with different transfectoma clones in conventional culture were not fully predictive for yields in the hollow fiber system. In contrast, differences in productivity between individual clones in the laboratory-scale Tecnomouse cell culture unit were comparable with those in the Maximizer system. Up to 200 mg of chimeric IgG were produced per day in one Maximizer bioreactor. © 1995 John Wiley & Sons, Inc.
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    Kinetics of ethanol production by recombinant Escherichia coli KO11 (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 356-365 
    Details
    ISSN: 0006-3592
    Keywords: Escherichia coli KO11 ; ethanol production ; kinetic model ; lignocellulosic hydrolysate ; fermentation, mixed sugar ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The fermentation kinetics for separate as well as simultaneous glucose and xylose fermentation with recombinant ethanologenic Escherichia coli KO11 are presented. Glucose and xylose were consumed simultaneously and exhibited mutual inhibition. The glucose exhibited 15 times stronger inhibition in xyclose fermentation than vice versa. The fermentation of condensate from steampretreated willow (Salix) was investigated. The kinetics were studied in detoxified as well as in nondetoxified condensate. The fermentation of the condensate followed two phases: First the glucose and some of the pentoses (xylose in addition to small amounts of arabinose) were fermented simultaneously, and then the remaining part of the pentoses were fermented. The rate of the first phase was independent of the detoxification method used, whereas the rate of the second phase was found to be strongly dependent. When the condensate was detoxified with overliming in combination with sulfite, which was the best detoxification method investigated, the sugars in the condensate, 9 g/L, were fermented in 11 h. The same fermentation took 150 h in nondetoxified condensate. The experimental data were used to develop an empirical model, describing the batch fermentation of recombinant E. coli KO11 in the condensate. The model is based on Monod kinetics including substrate and product inhibition and the sum of the inhibition exerted by the rest of the inhibitors, lumped together. © 1995 John Wiley & Sons, Inc.
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    Masthead (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260450501
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    Working at controlled water activity in a continuous process: The gas/solid system as a solution (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 387-397 
    Details
    ISSN: 0006-3592
    Keywords: transesterification ; water activity ; lipolytic enzymes ; gas ; bioreactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fusarium solani cutinase and Candida cylindracea lipase were used to catalyze a transesterification reaction in a continuous gas/solid bioreactor. In this system, a solid phase composed of a packed enzymatic preparation was continuously percolated with carrier gas which fed substrate and removed reaction products simultaneously. Different conditions of immobilization were used and compared to the results obtained with a nonsupported enzyme. The enzymatic activity was found to be highly dependent of a key parameter: water activity (aw). Biocatalyst stability was greatly influenced by water activity and the choice of immobilization technique for the enzymatic material. For free and adsorbed enzymes, water requirements exhibited optima which corresponded to the complete hydration coverage of the protein. These optima presented a good correlation with the isotherm sorption curves obtained for the different preparations. In this work are reported the results concerning the possibility of using a continuous system able to operate at controlled water activity in a heterogeneous medium. Lipolytic enzyme in such a system appears to be a new process for the biotransformation of volatile esters. © 1995 John Wiley & Sons, Inc.
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    High viable cell concentration fed-batch cultures of hybridoma cells through on-line nutrient feeding (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 579-587 
    Details
    ISSN: 0006-3592
    Keywords: hybridoma cells ; process control ; energy metabolism ; on-line nutrient feeding ; fed-batch culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A hybridoma cell line was cultivated in fed-batch cultures using a low-protein, serum-free medium. On-line oxygen uptake rate (OUR) measurement was used to adjust the nutrient feeding rate based on glucose consumption, which was estimated on-line using the stoichiometric relations between glucose and oxygen consumption. Through on-line control of the nutrient feeding rate, not only sufficients were supplied for cell growth and antibody production, but also the concentrations of glucose and other important nutrients such as amino acids were maintained at low levels during the cell growth phase. During the cultivation, cell metabolism changed from high lactate production and low oxygen consumption to low lactate production and high oxygen consumption. As a result the accumulation of lactate was reduced and the growth phase was extended. In comparison with the batch cultures, in which cells reached a concentration of approximately 2 × 106 cells/mL, a very high concentration of 1.36 × 107 cells/mL with a high cell viability (〉90%) was achieved in the fed-batch culture. By considering the consumption of glucose and amino acids, as well as the production of cell mass, metabolites, and antibodies, a well-closed material balance was established. Our results demonstrate the value of coupling on-line OUR measurement and the stoichiometric realations for dynamic nutrient feeding in high cell concentration fed batch cultures. © 1995 John Wiley & Sons, Inc.
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    Transformation capacities of chlorinated organics by mixed cultures enriched on methane, propane, toluene, or phenol (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 440-449 
    Details
    ISSN: 0006-3592
    Keywords: transformation capacity ; product toxicity ; oxygenase enzymes ; chlorinated organics ; trichloroethylene ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The degradation of trichloroethylene (TCE), chloroform (CF), and 1,2-dichloroethane (1,2-DCA) by four aerobic mixed cultures (methane, propane, toluene, and phenol oxidizers) grown under similar chemostat conditions was measured. Methane and propane oxidizers were capable of degrading both saturated and unsaturated chlorinated organics (TCE, CF, and 1,2-DCA). Toluene and phenol oxidizers degraded TCE but were not able to degrade CF, 1,2-DCA, or other saturated organics. None of the cultures tested were able to degrade perchloroethylene (PCE) or carbon tetrachloride (CC4). For the four cultures tested, degradation of each of the chlorinated organics resulted in cell inactivation due to product toxicity. In all cases, the toxic products were rapidly depleted, leaving no toxic residues in solution. Among the four tested cultures, the resting cells of methane oxidizers exhibited the highest transformation capacities (Tc) for TCE, CF, and 1,2-DCA. The Tc for each chlorinated organic was observed to be inversely proportional to the chlorine carbon ratio (Cl/C). The addition of low concentrations of growth substrate or some catabolic intermediates enhanced TCE transformation capacities and degradation rates, presumably due to the regeneration of reducing energy (NADH); however, addition of higher concentrations of most amendments reduced TCE transformation capacities and degradation rates. Reducing energy limitations and amendment toxicity may significantly affect Tc measurements, causing a masking of the toxicity associated with chlorinated organic degradation. © 1995 John Wiley & Sons, Inc.
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    Growth kinetics of glucose-limited petunia hybrida cells in chemostat cultures: Determination of experimental values for growth and maintenance parameters (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 42-52 
    Details
    ISSN: 0006-3592
    Keywords: Petunia hybrida ; chemostat cultures ; growth ; true growth yield ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: With glucose-limited continuous cultures of Petunia hybrida six steady states were obtained at specific growth rates varying from 0.0035 to 0.012 h-1 (corresponding with culture residence times varying from 285 to 85 h). The macromolecular and the elemental biomass composition which were determined in four steady states showed no major differences over the range of growth rates examined. During all six steady states specific subtrate and oxygen consumption as well as biomass and extracellular product formation rates were monitored. Moreover the specific activities of the mitochondrial cytochrome and alternative pathway were determined and used to estimate specific adenosine triphosphate (ATP) production rates. Data thus obtained were used in the determination of maintenance and true growth yield parameters. For the maintenance on glucose and ATP values of 0.0070 C-mol/C-mol/h and 0.034 mol/C-mol/h were obtained, respectively. True yields of biomass on glucose and ATP were 0.50 C-mol/C-mol and 0.28 C-mol/mol, respectively. © 1995 John Wiley & Sons, Inc.
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    Fundamental denitrification kinetic studies with Pseudomonas denitrificans (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 26-41 
    Details
    ISSN: 0006-3592
    Keywords: nitrate ; nitrite ; denitrification ; kinetics ; T effects ; pH effects ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fundamental kinetic studies on the reduction of nitrate, nitrite, and their mixtures were performed with a strain of Pseudomonas denitrificans (ATCC 13867). Methanol served as the carbon source and was supplied in excess (2:1 mole ratio relative to nitrate and/or nitrite). Nitrate and nitrite served as terminal electron acceptors as well as sources of nitrogen for biomass synthesis. The results were explained under the assumption that respiration is a growth-associated process. It was found that the sequence of complete reduction of nitrate to nitrogen gas is via nitrite and nitrous oxide.It was found that the specific growth rate of the biomass on either nitrate or nitrite follows Andrews inhibitory kinetics and nitrite is more inhibitory than nitrate. It was also found that the culture has severe maintenance requirements which can be described by Herbert's model, i.e., by self-oxidation of portions of the biomass. The specific maintenance rates at 30°C and pH 7.1 were found to be equal to about 28% of the maximum specific growth rate on nitrate and 23% of the maximum specific growth rate on nitrite. Nitrate and nitrite were found to be involved in a cross-inhibitory noncompetitive kinetic interaction. The extent of this interaction is negligible when the presence of nitrite is low but is considerable when nitrite is present at levels above 15 mg/L.Studies on the effect of temperature have shown that the culture cannot grow at temperatures above 40°C. The optimal temperature for nitrate or nitrite reduction was found to be about 38°C. Using an Arrhenius expression to describe the effect of temperature on the specific growth rates, it was found that the activation energy for the use of nitrate by the culture is 8.6 kcal/mol and 7.21 kcal/mol for nitrite. Arrhenius-type expressions were also used in describing the effect of temperature on each of the parameters appearing in the specific growth rate expressions. Studies on the effect of pH at 30°C have shown that the culture reduces nitrate optimally at a pH between 7.4 and 7.6, and nitrite at a pH between 7.2 and 7.3. © 1995 John Wiley & Sons, Inc.
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    Two-stage batch process for the production of ajmalicine by Catharanthus roseus: The link between growth and production stage (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 53-59 
    Details
    ISSN: 0006-3592
    Keywords: ajmalicine ; Catharanthus roseus ; alkaloid formation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The link between the growth stage and the production stage in a two-stage batch process was investigated using (filtered) inocula from different periods of the stationary phase of the growth cycle. In the production stage, ajmalicine production by Catharanthus roseus in a 3-L stirred tank reactor was induced with a high glucose concentration (80 g/L). Ajmalicine production in cultures started with cells from the late stationary phase was five times higher than in cultures started with cells from the early stationary phase. After transfer to the production stage, cells from the early stationary phase showed a transient increase in respiration and enzyme induction, followed by culture browning. In contrast, cells in the late stationary phase showed a typical induction pattern: constant respiration, and permanent enzyme induction. A striking similarity between the geraniol-10-hydroxylase (G10H) activity and the ajmalicine accumulation profile could be observed in all cultures, suggesting that G 10H regulated ajmalicine production in this investigation. The intracellular nitrate concentration was significantly higher in the inoculum showing a high ajmalicine production than in the inoculum with a low production. Consequently, nitrate may act as a marker for the start of the production stage: as soon as the nitrate is depleted in the growth medium secondary metabolism can be induced. © 1995 John Wiley & Sons, Inc.
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    Announcement from the publisher (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. ii 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260480202
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    Effect of cDNA copy number on secretion rate of activated protein C (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 22-27 
    Details
    ISSN: 0006-3592
    Keywords: cDNA copy number ; gene dosage ; recombinant protein production ; posttranslational modification ; BHK ; secretion ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The secretion rate of activated protein C (APC) by BHK cells was increased 35-fold by increasing the cDNA copy number per cell from 50 to 240. In this range, the relation between APC secretion and cDNA copy number was not linear and the rate of APC secretion per cDNA copy increased sevenfold. This apparent cooperative effect of multiple cDNA copies could be related to their integration in tandem. For cDNA copy numbers higher than 240, the APC secreation rate per cDNA and per cell decreased dramatically. The γ-carboxylation of glutamic acid residues, a posttranslational modification required for APC biological activity, was also investigated. The proportion of APC that was fully γ-carboxylated decreased as the secretion rate of APC increased. © 1995 John Wiley & Sons, Inc.
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    Selective adsorption of proteins to their ligands covalently immobilized onto microfibers (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 557-566 
    Details
    ISSN: 0006-3592
    Keywords: polyester fiber ; immobilization ; protein A ; antigen ; antibody ; immunoadsorbent ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Following ozone oxidation of polyester microfibers of 3.5 μm average diameter and 0.83 m2/g specific area, the fiber surface was subjected to graft polymerization of acrylic acid and subsequently immobilized with serologically active proteins including Staphylococcus aureus protein A, a specific antigen, and a specific antibody. The immobilization reaction was mediated by a watersoluble carbodiimide, which allowed formation of a co-valent linkage between the ligand proteins and the grafted poly(acrylic acid)chains. The yields of the immobilized ligand proteins were of the order of 1 mg/g fiber. Their binding affinity and capacity to respective specific proteins were studied in vitro from a buffered solution and serum. It was found that the specific proteins were selectively adsorbed with dissociation constants as low as 1× 10-6 M, suggesting the adsorption to take place through highly specific protein-protein interaction. An addition of serum albumin did not significantly affect the specific binding, regardless of the ligand proteins. The binding capacity ranged from 1 × 10-13 to 1× 10-11 mol/cm2 primarily depending on the surface density of the immobilized ligands and the number of their binding sites per molecule. © 1995 John Wiley & Sons Inc.
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    Membrane anchored protein production from spheroid, porous, and solid microcarrier chinese hamster ovary cell cultures (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 550-556 
    Details
    ISSN: 0006-3592
    Keywords: spheroids ; porous and solid microcarriers ; CHO ; controlled release ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of the microcarrier type on the performance of a controlled release process used to produce a recombinant glycosyl-phosphatidylinositol anchored protein was investigated. Chinese hamster ovary (CHO) cells expressing the human melanoma tumor antigen (p97) were cultured in 10% serum on Cultispher-GH porous microcarriers and then, for protein production, maintained in 2% serum. Cells were harvested every 48 h and p97 was recovered at 90 μg/mL and 40% purity. Harvested p97 concentrations were increased by harvestingfrom spheroid (241 μg/mL) and smaller porous microcarrier, Cultispher-G (167 μg/mL) cultures. The low total cell specific p97 production of cells cultured on Cultispher-GH was due to necrosis of cells within the beads, decreased p97 expression of the immobilized cells, dilution by the liquid (up to 40% volume) associated with settled beads, and incomplete recovery of p97 from within the beads. Cells cultured on solid microcarriers, Cytodex-1, had the highest cell viability and cell specific p97 production, It is recommended that a two-stage cyclic harvesting process of cells cultured on small Cultispher-G or on Cytodex-1 beads would minimize protein loss and maximize cell specific protein recovery. © 1995 John Wiley & Sons Inc.
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    Overexpression of bcl-2, apoptosis suppressing gene: Prolonged viable culture period of hybridoma and enhanced antibody production (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 118-122 
    Details
    ISSN: 0006-3592
    Keywords: apoptosis ; bcl-2 ; hybridoma ; cell survival ; antibody productivity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Human bcl-2 DNA was introduced into mouse hybridoma 2E3 cells and expressed at a high level by using BCMGSneo vector, which reportedly amplifies as multiple copies in the cells independently of their chromosomes. The high expression of bcl-2 in BCMGSneo-bcl-2 transfectants was confirmed by western blotting. In batch cultures, the overexpression of bcl-2 raised the maximum viable cell density by 45%, delayed the initiation of apoptosis by 2 days, and prolonged the viable culture period by 4 days. The delayed initiation of apoptosis was detected by emergence of the ladder pattern on DNA electrophoresis and increase of the dead cell number. The bcl-2 transfectants produced lgG1 fourfold per batch culture in comparison with 2E3 cells transfected with BCMGSneo but not with bcl-2: a little less than twofold due to the improved survival of the cells and more than twofold due to the enhanced lgG1 production rate per cell of the bcl-2 transfectants. The method to engineer hybridoma cells genetically with bcl-2 using BCMGSneo vector for increasing viability and productivity would be widely applied for improving antibody productivity of hybridoma cultures. © 1995 John Wiley & Sons, Inc.
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    Enzymatic glucosylation of hydrophobic alcohols in organic medium by the reverse hydrolysis reaction using almond-β-D-glucosidase (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 109-116 
    Details
    ISSN: 0006-3592
    Keywords: glucosylation ; alcohol ; hydrolysis, reverse ; galactoside ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Alkyl β-D-glucosides were synthesized from D-glucose and alcohols by reverse hydrolysis using the commercially available almond β-D-glucosidase in 9:1 (v/v) acetonitrile-water medium. The main characteristics of this enzyme-catalyzed glucosylation were established by using 2-hydroxybenzyl alcohol. The reaction is entirely regio- and stereoselective. The solvent plays a fundamental role because, by decreasing the water concentration in the medium, the shift of the reaction equilibrium toward synthesis is realized without using an excessive amount of alcohol. Nevertheless, a minimum amount of water is necessary to maintain the enzyme activity. In contrast to the use of the enzyme in aqueous medium, the pH of the added water in acetonitrile did not influence the synthesis. Using this procedure, we have conducted systematic glucosylation of numerous alcohols and we have investigated enzyme specificity and alcohol reactivity. The enzyme has a pronounced affinity for the alcohols containing a phenyl group, and enantioselectivity for the aglycon is obtained with 1-phenylethyl alcohol. Moreover, by using almond β-D-glucosidase it was also possible to synthesize alkyl β-D-galactosides. © 1995 John Wiley & Sons, Inc.
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    Development of a predictive description of an immobilized-cell, three-phase, fluidized-bed bioreactor (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 139-146 
    Details
    ISSN: 0006-3592
    Keywords: fluidized-bed bioreactor ; concentration profile ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A fully predictive mathematical description of a three-phase, tapered, fluidized-bed bioreactor is developed. This mathematical model includes the effects of the tapered bed, variable dispersion coefficient, and variable solid holdup upon the concentration profiles developed in the bed. In addition, the effect of the concentration profile which is developed inside the biocatalyst bead is included by means of an effectiveness factor calculation. Using accepted correlations for the dispersion coefficient and for the liquid, gas, and solid holdup in the bed, the model is fully predictive. The model was found to adequately predict experimental obtained concentration profiles. Then, the model was used to examine the various phase holdups through the bed and the degree to which the dispersion coefficient varied through the bed. The effect of changes in these calculated variables upon the reaction rate is discussed. © 1995 John Wiley & Sons, Inc.
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    Fed-batch feeding and induction policies that improve foreign protein synthesis and stability by avoiding stress responses (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 596-608 
    Details
    ISSN: 0006-3592
    Keywords: amino acid addition ; protein stability ; protease ; fed-batch ; Escherichia coli ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this work, feeding policies aimed to avoid cellular stress responses as indicated by an increase in ATP-dependent proteolysis are tested. A set of experiments was carried out where glucose, IPTG (inducer), and phenylalanine (rate-limiting precursor) were added gradually in a fed-batch fashion. A significant increase in CAT activity was found compared with pulse-induction. In addition, there was a substantial increase in the rate of CAT synthesis as well as in the final specific CAT activity when phenylatanine and the inducer were added simultaneously. CAT degradation was confirmed through Western blotting analysis. Protease analysis (SDS-GPAGE) indicated lower proteolytic activity for the IPTG and phenylalanine fed-batch cases. GroEL immunoas-says indicated that amplification of stress proteins occurred upon CAT induction. This research impacts the yield of soluble cytoplasmic proteins in Escherichia coli and suggests that metabolically based induction/feeding policies are beneficial. © 1995 John Wiley & Sons Inc.
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    Formation of nitrifying biofilms on small suspended particles in airlift reactors (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 585-595 
    Details
    ISSN: 0006-3592
    Keywords: biofilm ; wastewater treatment ; airlift reactor ; nitrification ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For a stable and reliable operation of a BAS-reactor a high, active biomass concentration is required with mainly biofilm-covered carriers. The effect of reactor conditions on the formation of nitrifying biofilms in BAS-reactors was investigated in this article. A start-up strategy to obtain predominantly biofilm-covered carriers, based on the balancing of detachment and a biomass production per carrier surface area, proved tp be very successful. The amount of biomass and the fraction of covered carrier were high and development of nitrification activity was fast, leading to a volumetric conversion of 5 kgN · m-3 · d-1 at a hydraulic retention time of 1h. A 1-week, continuous inoculation with suspended purely nitrifying microorganisms resulted in a swift start-up compared with batch addition of a small number of biofilms with some nitrification activity. The development of nitrifying biofilms was very similar to the formation of heterotrophic biofilms. In contrast to heterotrophic bio-films, the diameter of nitrifying biofilms increased during start-up. The detachment rate from nitrifying biofilms decreased with lower concentrations of bare carrier, in a fashion comparable with heterotrophic biofilms, but the nitrifying biofilms were much more robust and resistant. Standard diffusion theory combined with reaction kinetics are capable of predicting the activity and conversion of biofilms on small suspended particles. © 1995 John Wiley & Sons Inc.
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    Thermal isoelectric precipitation of α-lactalbumin from a whey protein concentrate: Influence of protein-calcium complexation (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 121-130 
    Details
    ISSN: 0006-3592
    Keywords: α-lactalbumin ; whey ; isoelectric precipitation ; calcium complexation ; modeling ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The selective precipitation of α-lactalbumin (α-LA) at a pH around its isoelectric point (4.2) under heat treatment is the basis for a fractionation process of whey proteins. As precipitation is a phenomenon dependent on the protein hydrophobicity, and as the release of the tightly bound calcium occurring at pH around 4 modifies the α-LA hydrophobicity, the specific role of calcium on isoelectric precipitation is investigated. A study of the extent of α-LA precipitation in a whey protein concentrate under various operating conditions of pH, temperature, protein concentration, and calcium content is presented. We propose a mechanism for this phenomenon as a combination of a complexation equilibrium and of an irreversible precipitation, to account for the influence of temperature, α-LA concentration total ionic content, and calcium concentration, and also to estimate the complexation equilibrium constant. © 1995 John Wiley & Sons, Inc.
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    Influence of substrate oscillations on acetate formation and growth yield in Escherichia coli glucose limited fed-batch cultivations (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 139-146 
    Details
    ISSN: 0006-3592
    Keywords: Escherichia coli ; fed-batch ; acetate ; glucose ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A Large bioreactor is an inhomogenous system with concentration gradients which depend on the fluid dynamics and the mass transfer of the reactor, the feeding strategy, the saturation constant, and the cell density. The responses of Escherichia coli cells to short-term oscillations of the carbon/energy substrate in glucose limited fed-batch cultivations were studied in a two-compartment reactor system consisting of a stirred tank reactor (STR) and an aerated plug flow reactor (PFR) as a recycle loop. Short-term glucose excess or starvation in the PFR was simulated by feeding of glucose to the PFR or to the STR alternatively. The cellular response to repeated short-term glucose excess was a transient increase of glucose consumption and acetate formation. But, there was no accumulation of acetate in the culture, because it was consumed in the STR part where the glucose concentration was growth limiting. However, acetate accumulated during the cultivation if the oxygen supply in the PFR was insufficient, causing higher acetate formation. The biomass yield was then negatively influenced, which was also the case if the PFR was used to simulate a glucose starvation zone. The results suggest that short-term heterogeneities influence the cellular physiology and growth, and can be of major importance for the process performance. © 1995 John Wiley & Sons, Inc.
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    Growth kinetics of vitis vinifera cell suspension cultures: I. Shake flask cultures (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 131-138 
    Details
    ISSN: 0006-3592
    Keywords: Vitis vinifera ; plant cell culture ; nutrients ; cell division ; growth ; oxygen consumption ; anthocyanins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Vitis vinifera cell suspension cultures carried out in shake flasks were closely examined for biomass growth and cell division in relation to carbohydrate, NH4, NO3PO4, and dissolved oxygen (DO)consumption. After inoculation, the oxygen uptake rate of the cultures measured on-tine was observed to increase continuously to a maximum value of 3.8 mmol O2L-1h-1 at day 7 when cell division ceased and dissolved oxygen reached its lowest level of 17% air saturation. During this first phase of growth, the specific oxygen uptake rate remained constant at ∼0.6 mmol 02 O2 g-1 dw h-1or ∼2.2 μmol O2, (106 cells)-1 h-1 whereas dry biomass concentration increased exponentially from 1.5 to 6.0 g dw L-1. Thereafter, dry biomass concentration increased linearly to ∼14 g dw L-1 at day 14 following nitrate and carbohydrate uptake. During this second phase of growth, the biomass wet-to-dry weight ratio was found to increase in an inverse relationship with the estimated osmotic pressure of the culture medium. This corresponded to inflection points in the dry and wet biomass concentration and packed cell volume curves. Furthermore, growth and nutrient uptake results suggest that extracellular ammonium or phosphate ion availability may limit cell division. These findings indicate that cell division and biomass production of plant cell cultures may not always be completely associated, which suggests important new avenues to improve their productivity. © 1995 John Wiley & Sons, Inc.
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    Production and properties of a bifunctional fusion protein that mediates attachment of vero cells to cellulosic matrices (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 147-154 
    Details
    ISSN: 0006-3592
    Keywords: arg-gly-asp ; cellulose ; protein production ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The sequence Arg-Gly-Asp (RGD) in extracellular matrix proteins such as fibronectin, collagen, and laminin mediates cell attachment by interacting with proteins of the integrin family of cell surface receptors. A gene fusion encoding the RGD-containing peptide, fused to the C-terminus of a cellulose-binding domain (CBD/RGD), was expressed in Escherichia coli. Cultures produced up to 50 mg of CBD/RGD per liter, most of which was extracellular. It was purified from the culture supernatant by affinity chromatography on cellulose. CBD/RGD promoted the attachment of green monkey Vero cells to polystyrene and cellulose acetate. Attachment was inhibited by small synthetic peptides containing the RGD sequence. CBD/RGD was as effective as collagen in promoting the attachment of Vero cells to Cellsnow™ microcarriers. © 1995 John Wiley & Sons, Inc.
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    Protein recovery from cell debris using rotary and tangential crossflow microfiltration (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 155-164 
    Details
    ISSN: 0006-3592
    Keywords: cell debris ; protein recovery ; membranes ; microfiltration ; bacterial lysate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Protein recovery from a bacterial lysate was accomplished using microfiltration membranes in a flat crossflow filter and in a cylindrical rotary filter. Severe membrane fouling yielded relatively low long-term permeate flux values of 10-4-10-3 cm/s (where I cm/s = 3.6 × 104 L/m2 - h). The permeate flux was found to be nearly independent of transmembrane pressure and to increase with increasing shear rate and decreasing solids concentration. The flux increased with shear to approximately the one-third power or greater for the flat filter and the one-half power or greater for the rotary filter; the stronger dependence for the rotary filter is thought to result from Taylor vortices enhancing the back transport of debris carried to the membrane surface by the permeate flow. The average protein transmission or sieving coefficient was measured at approximately 0.6, but considerable scatter in the transmission data was observed. The largest sieving coefficients were obtained for dilute suspensions at high shear rate. The rotary filter provided higher fluxes than did the flat filter for dilute suspensions, but not for concentrated suspensions. © 1995 John Wiley & Sons, Inc.
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    On-line state recognition in a yeast fed-batch culture using error vectors (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 165-173 
    Details
    ISSN: 0006-3592
    Keywords: error vector ; physiological state recognition ; fuzzy inference ; metabolic reaction model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The physiological states with respect to cell growth and ethanol production in a yeast fed-batch culture expressed in linguistic form could be recognized on-line by fuzzy inferencing based on error vectors. The error vector was newly defined here in a macroscopic elemental balance equation. The physiological states for cell growth and ethanol production were characterized by error vectors using many experimental data from fed-batch cultures. Fuzzy membership functions were constructed from the frequency distributions of the error vectors and state recognition was performed by fuzzy inferencing. In particular, an unusual physiological state for a yeast cultivation, in which aerobic ethanol production was accompanied by very low cell growth, could be recognized accurately. According to the results of the state recognition, an energy parameter, the P/O ratio in the metabolic reaction model was adaptively estimated, and the cell growth was successfully evaluated with the estimated P/O. © 1995 John Wiley & Sons, Inc.
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    Effect of membrane morphology and operation on protein deposition in ultrafiltration membranes (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 174-180 
    Details
    ISSN: 0006-3592
    Keywords: ultrafiltration membranes ; protein fouling ; BET measurements ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Membrane morphology is compared to protein depostion under passive adsorption and ultrafiltration conditions. Solute resistance of protein deposits for membranes of varying roughness, structure, and permeability can vary dramatically with operating conditions. Using Brunauer-Emmett-Teller adsorption isotherm (BET), study of the internal area and accessibility of several uttrafiltration membranes to protein deposition allows better understanding of the fouling mechanisms and interpretation of adsorbed protein quantities. © 1995 John Wiley & Sons, Inc.
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