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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 53 (1997), S. 372-378 
    ISSN: 0006-3592
    Keywords: glucose ; lactate ; on-line monitoring ; mammalian cell culture ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: On-line monitoring and control of cell culture fermentation is important for optimal and consistent production of biologicals. In this work, glucose and lactate concentrations are monitored on-line using a commercially available analyzer (Model 2700, Yellow Springs Instruments, Yellow Springs, OH) during batch and perfusion hybridoma cell fermentation. Cell free samples from the reactor are obtained using a 0.45 μm hollow fiber filtering system placed in a circulation loop. The samples were analyzed at specified times and the data are collected on a computer. A process control strategy was developed to control the concentrations of glucose and lactate in a perfusion reactor where the feed rate is adjusted to maintain their concentrations at desired set points. Hybridoma cells (A10G10) were cultivated in a high density perfusion culture where cell density increased from 2 to 14 million cells/mL. During this period the control algorithm successfully adjusted the perfusion rate while maintaining constant glucose and lactate concentrations. Glucose consumption and lactate accumulation rates as well as net lactate yield on glucose were monitored continuously during perfusion culture. These metabolic rates were observed to be independent of cell concentration and were used for the estimation of viable cell density in the reactor. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 372-378, 1997.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0006-3592
    Keywords: one-line monitoring ; fermentation ; cell culture ; monoclonal antibodies ; real-time immunoassays ; BioCad/RPM ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: On-line, “real-time” monitoring of product concentration is important for mammalian cell culture fermentation. The continuous measurement of monoclonal antibodies allows for instantaneous determination of cell productivity and effective manipulation of the fermentor operating conditions for optimal production. This article will present the evaluation and application of a BioCad/RPM system (Per Septive Biosystems) for rapid analysis of lgG concentration for hybridoma cell cultivation. Several commercial crossflow filtration devices are tested for low protein retention and fouling properties. A protein G column is used successfully for analyzing about 400 samples of lgG1, without significant loss in separation efficiency. The Immuno Detection system is integrated into a computer-controlled 15-L fermentor. This fermentor could be operated in batch and perfusion modes with cell densities up to 20 million cells/mL. A continuous cell-free sample stream obtained by a hollow fiber filter system is introduced to the BioCad/RPM for analysis. The speed of this system allows for real-time monitoring even at high densities with fast dynamics. A murine hybridoma cell (A10G10) is cultivated in batch and continuous reactors and antibody concentration is measured continuously with complete sterility. The results are compared to offline measurements with good agreement. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 495-502 
    ISSN: 0006-3592
    Keywords: optical cell density probes ; turbidity probes ; on-line monitoring ; in situ probes ; mammalian cell bioreactors/fermentors ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: On-line optical cell density probes were implemented to continuously monitor the cell densities in mammalian cell bioreactor and to achieve advanced bioreactor controls. We tested cell density probes from six manufacturers in high cell density bioreactors. When externally calibrated, Aquasant and Ingold backscattering probes produced the most linear probe responses (PR) versus cell density (CD), followed by the ASR and Cerex laser probes. Monitek and Wedgewood transmission probes had lower resolutions. All probes were tested in two murine hybridoma fermentations. Cell densities varied between 1 × 106 cells/mL to 20 × 106 cells/mL and the bioreactors were operated for 5 to 7 weeks. For our bioreactors, Aquasant, Ingold, ASR, Wedgewood, and Monitek probes gave satisfactory responses. Little fouling was observed with any probe at the end of 2 weeks. Fouling was a possibility after 3 weeks in one bioreactor but its effect can be easily corrected. Cell density control and specific perfusion control of bioreactors based on the Aquasant probe were achieved. Implementation of cell density probe based perfusion control, instead of “step perfusion adjustments” based on manual hemacytometer control, will result in smoother operation, healthier cultures, increased medium delivery efficiency, and reduced operational excursions. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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