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  • 1
    Electronic Resource
    Electronic Resource
    Increased oxygen mass transfer rates from single bubbles in microbial systems at low reynolds numbers (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 647-681 
    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 presence of microorganisms have been shown to increase by over 40% the mass transfer rates from small oxygen bubbles at low Reynolds number flow. This increase was found to be due only to the microbe cells as inert particles disrupting the quasi-static liquid surface film surrounding the gas bubble and thus decreasing the gas-liquid interfacial resistance. The observed increase in oxygen mass transfer rates was not dependent on cell viability, no effect was noted due to cell-liquid interfacial resistance, nor was the phenomenon due to altering the physical properties of the liquid during cell propagation. These results were obtained in a unique plexiglass apparatus designed for observing under a microscope a small (0.4 mm dia.) stationary oxygen bubble collapsing into a flowing fluid. The oxygen bubble was injected by a small hypodermic needle and the fluid was suspensions of the yeast Candida intermedia, the bacterium Pseudomonas ovalis, 0.3μ alumina, as well as base points of cell free broth and pure water. Several well-known chemical inhibitors of oxidative phosphorylation were used to limit cell oxygen uptake. Calculations of oxygen mass transfer rates were compared with the semi-empirical model of Frössling, the circulating sphere model of Levich, and the rigid sphere concentration boundary layer model of Fried-lander, the latter two showing strong Reynolds number dependence that may be due to radial fluid motion.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260110411
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  • 2
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260110302
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  • 3
    Electronic Resource
    Electronic Resource
    Human interferon production with diploid fibroblast cells grown on microcarriers (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 21 (1979), S. 433-442 
    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 variety of diploid human fibroblast lines have been successfully grown to high densities (〉106 cell/ml) on recently developed microcarriers. Interferon induction using poly I·poly C and a superinduction procedure resulted in yields greater than 10,000 units/ml with one cell line. A direct comparison of microcarrier cultures to roller bottle cultures showed equivalent interferon yields on a per cell basis and some apparent differences relating to optimum inducer concentrations and kinetics of interferon accumulation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260210306
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  • 4
    Electronic Resource
    Electronic Resource
    Enhancing gas-liquid mass transfer rates in non-newtonian fermentations by confining mycelial growth to microbeads in a bubble column (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 25 (1983), S. 2873-2887 
    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 performance of a penicillin fermentation was assessed in a laboratory-scale bubble column fermentor, with mycelial growth confined to the pore matrix of celite beads. Final cell densities of 29 g/L and penicillin titres of 5.5 g/L were obtained in the confined cell cultures. In comparison, cultures of free mycelial cells grown in the absence of beads experienced dissolved oxygen limitations in the bubble column, giving only 17 g/L final cell concentrations with equally low penicillin titres of 2 g/L. The better performance of the confined cell cultures was attributed to enhanced gas liquid mass transfer rates, with mass transfer coefficients (kLa) two to three times higher than those determined in the free cell cultures. Furthermore, the confined cell cultures showed more efficient utilization of power input for mass transfer, providing up to 50% reduction in energy requirements for aeration.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260251206
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  • 5
    Electronic Resource
    Electronic Resource
    A mechanistic analysis of the inoculum requirement for the cultivation of mammalian cells on microcarriers (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 585-595 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For the cultivation of mammalian cells on microcarriers a minimum inoculum concentration is required to initiate cell attachment and subsequent cell growth. A critical cell number model has been proposed to elucidate the mechanism of the inoculum requirement. In this model it was hypothesized that after inoculation a critical number of cells per microcarrier is required for normal growth to occur; failure to acquire enough cells will impede cell growth. This critical cell number model was expressed mathematically and used to simulate cell distribution and growth on microcarriers under different cultivation conditions. By comparing the simulated growth kinetics with the experimental results, the actual critical cell number per microcarrier was identified. The critical number could be reduced by employing an improved medium for the cultivation.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260270507
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  • 6
    Electronic Resource
    Electronic Resource
    Fluorescence sensing of fermentation parameters using fiber optics (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 32 (1988), S. 55-63 
    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 method has been developed for measuring fermentation parameters such as dissolved oxygen, pH, and cell density that differs from traditional techniques that require electrodes and off-line samples. Fluorescent indicators, each sensitive to a single variable, are dissolved directly into a fermentation broth. A fiber-optic probe fluorimeter measures the fluorescence intensities that can then be correlated with parameter values. In addition, an integrated scatter scanning technique can be used to monitor cell density in situ. Results have been obtained using simulated baker's yeast broth and during actual baker's yeast fermentations.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260320109
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  • 7
    Electronic Resource
    Electronic Resource
    Separation and concentration of amino acids using liquid emulsion membranes (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 32 (1988), S. 604-615 
    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 separation and concentration of amino acids using liquid emulsion membranes (LEMs) are discussed. Using L- phenylalanines as a model solute, it is experimentally shown using a facilitated transport system that separation and concentration can be simultaneously achieved. The rate of separation, final product concentration, and membrane swell are shown to increase with increasing chloride driving forces in the membrane, These effects are shown to be insensitive to the particular salt used as the driving force. Changes in the carrier concentration are shown to result in higher initial fluxes and higher swell rates. Hydrodynamically induced membrane breakage is minimal for the system under consideration. Experiments indicate that osmotically induced water transport (“swelling”) in the LEM system is mediated by both the carrier and the emulsion-stabilizing surfactant. The data suggest that this swell is a diffusion-limited process. The specificity of the carrier is examined and is found to be directly related to the hydrophobicity of the solute. Strategies for optimizing LEM formulations are discussed. Emphasis is placed on the hydration characteristics of the surfactant and the specificity of the carrier.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260320505
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  • 8
    Electronic Resource
    Electronic Resource
    Production of human immune interferon by recombinant mammalian cells cultivated on microcarriers (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 33 (1989), S. 1182-1190 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recombinant Chinese hamster ovary (rCHO) cells were cultivated on microcarriers for the production of human immune (Gamma) interferon. The effect of basal medium, serum, and microcarrier concentration on interferon production was investigated. The specific interferon productivity in the post-confluent stage was similar to that in the growth stage. Control of the pH results in a significant improvement in the volumetric interferon production. The volumetric production rate of interferon by these rCHO cells did not decrease after one month of cultivation on microcarriers.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260330914
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  • 9
    Electronic Resource
    Electronic Resource
    Strategies for reducing solvent toxicity in extractive fermentations (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 716-722 
    Details
    ISSN: 0006-3592
    Keywords: κ-carrageenan matrix ; Lactobacillus delbrueckii ; toxicity ; solvent diffusion ; extractive fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The toxicity of an Alamine 336/oleyl-alcohol extraction system on Lactobacillus delbrueckii was investigated. It was shown that the solvent affected the cells through the water-soluble portion and the immiscible portion of the solvent. While immobilization significantly protected the cells from the immiscible solvent phase, the water-soluble part of the solvent still caused toxicity to the microorganisms due to diffusion of the solvent into the matrix. Adding soybean oil to the κ-carrageenan matrix could trap the diffusing solvent molecules, and therefore reduce the toxic effect from the water soluble portion of the solvent. The protective ability of soybean oil was quantified through mathematical modeling and experimentation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260370805
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  • 10
    Electronic Resource
    Electronic Resource
    Estimating cell concentration in the presence of suspended solids: A light scatter technique (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 875-888 
    Details
    ISSN: 0006-3592
    Keywords: cell concentration ; light scatter ; solid substrate ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel sensor was developed, based on light scatter, to estimate the cell concentration in the presence of suspended solids. The light scatter properties of cells in the presence of suspended solids were investigated. Two crucial observations were made: first, that the light scatter from cells is essentially a linear function of cell concentration and, second, that invariant regions are present in the light scatter spectrum of cell/solid substrate mixtures. Invariant regions are wavelength intervals of the light scatter spectrum in which the light scatter reading is independent of solid substrate concentration and only a function of cell concentration. The occurrence of invariant regions is the key behavior which allowed the quantification of cell concentration in the presence of suspended solids.An algorithm was developed for the estimation, from light scatter data, of cell concentration in the presence of solid substrate. The light scatter approach was validated by comparing cell concentrations estimated by this technique to those obtained from DNA and carbon dioxide evolution rate measurements during a series of fermentations. The model system used was Bacillus subtilis var sakainensis ATCC 21394 growing on fishmeal as the sole nitrogen source.A model was developed based on the interactions of scatter and absorbance. This model reflects the hypothesis that invariant regions are caused by changes in the absorbance of the solid substrate as a function of wavelength. © 1992 John Wiley & Sons, Inc.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260400803
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