title: A Novel Application for Low Frequency Electrochemical Impedance Spectroscopy as an Online Process Monitoring Tool for Viable Cell Concentrations.
abstract: New approaches in process monitoring during industrial fermentations are not only limited to classical pH, dO₂ and offgas analysis, but use different in situ and online sensors based on different physical principles to determine biomass, product quality, lysis and far more. One of the very important approaches is the in situ accessibility of viable cell concentration (VCC). This knowledge provides increased efficiency in monitoring and controlling strategies during cultivations. Electrochemical impedance spectroscopy-EIS-is used to monitor biomass in a fermentation ofE. coliBL21(DE3), producing a recombinant protein using a fed batch-based approach. Increases in the double layer capacitance (Cdl), determined at frequencies below 1 kHz, are proportional to the increase of biomass in the batch and fed batch phase, monitored in offline and online modes for different cultivations. A good correlation of Cdlwith cell density is found and in order to get an appropriate verification of this method, different state-of-the-art biomass measurements are performed and compared. Since measurements in this frequency range are largely determined by the double layer region between the electrode and media, rather minor interferences with process parameters (aeration, stirring) are to be expected. It is shown that impedance spectroscopy at low frequencies is a powerful tool for cultivation monitoring.
authors.affiliation: Research Division Biochemical Engineering, Institute of Chemical Engineering, Vienna University of Technology, Vienna 1060, Austria. christoph.slouka@tuwien.ac.at.|Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, Institute of Chemical Engineering, Vienna University of Technology, Vienna 1060, Austria. christoph.slouka@tuwien.ac.at.
authors.forename: Christoph
authors.initials: C
authors.lastname: Slouka
authors.affiliation: Research Division Biochemical Engineering, Institute of Chemical Engineering, Vienna University of Technology, Vienna 1060, Austria. david.wurm@tuwien.ac.at.
authors.forename: David J
authors.initials: DJ
authors.lastname: Wurm
authors.affiliation: Institute for Energy Systems and Thermodynamics, Vienna University of Technology, Vienna 1060, Austria. georg.brunauer@tuwien.ac.at.
authors.forename: Georg
authors.initials: G
authors.lastname: Brunauer
authors.affiliation: Research Division Electrochemistry, Institute of Chemical Technology and Analytics, Vienna University of Technology, Vienna 1060, Austria. andreas.welzl@tuwien.ac.at.
authors.forename: Andreas
authors.initials: A
authors.lastname: Welzl-Wachter
authors.affiliation: Research Division Biochemical Engineering, Institute of Chemical Engineering, Vienna University of Technology, Vienna 1060, Austria. oliver.spadiut@tuwien.ac.at.|Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, Institute of Chemical Engineering, Vienna University of Technology, Vienna 1060, Austria. oliver.spadiut@tuwien.ac.at.
authors.forename: Oliver
authors.initials: O
authors.lastname: Spadiut
authors.affiliation: Research Division Electrochemistry, Institute of Chemical Technology and Analytics, Vienna University of Technology, Vienna 1060, Austria. juergen.fleig@tuwien.ac.at.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Fleig
authors.affiliation: Research Division Biochemical Engineering, Institute of Chemical Engineering, Vienna University of Technology, Vienna 1060, Austria. christoph.herwig@tuwien.ac.at.|Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, Institute of Chemical Engineering, Vienna University of Technology, Vienna 1060, Austria. christoph.herwig@tuwien.ac.at.
authors.forename: Christoph
authors.initials: C
authors.lastname: Herwig
mesh_terms: D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D058266:Dielectric Spectroscopy / Q000379:methods*; D004926:Escherichia coli / Q000378:metabolism; D005285:Fermentation / Q000235:genetics / Q000502:physiology; D021241:Spectrometry, Mass, Electrospray Ionization
keywords: Escherichia coli; impedance spectroscopy; online biomass monitoring; viable cell count