title: Newly designed and validated impedance spectroscopy setup in microtiter plates successfully monitors viable biomass online.
abstract: In microtiter plates, conventional online monitoring of biomass concentration based on optical measurements is limited to transparent media: It also cannot differentiate between dead or viable biomass or suspended particles. To address this limitation, this study introduces and validates a new online monitoring setup based on impedance spectroscopy for detecting only viable biomass in 48- and 96-well microtiter plates. The setup was first validated electronically and characterized by determining the cell constants of the measuring geometry. Defined cell suspensions of Ustilago maydis, Hansenula polymorpha, Escherichia coli and Bacillus licheniformis were characterized to find, among other parameters, the most suitable frequency range and the characteristic frequency of β-dispersion for each organism. Finally, the setup was exemplarily applied to monitor the growth of Hansenula polymorpha online. As reference, three different parallel cultures were performed in established cultivation systems. This new online monitoring setup based on impedance spectroscopy is robust and enables precise measurements of microbial biomass concentration. It is promising for future high-throughput applications.
authors.affiliation: AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Luchterhand
authors.affiliation: AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Jannis
authors.initials: J
authors.lastname: Nolten
authors.affiliation: Zurich Instruments AG, Zurich, Switzerland.
authors.forename: Sadik
authors.initials: S
authors.lastname: Hafizovic
authors.affiliation: AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Tino
authors.initials: T
authors.lastname: Schlepütz
authors.affiliation: AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Sandra Janine
authors.initials: SJ
authors.lastname: Wewetzer
authors.affiliation: AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Pach
authors.affiliation: AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Meier
authors.affiliation: AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Wandrey
authors.affiliation: AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany. jochen.buechs@avt.rwth-aachen.de.
authors.forename: Jochen
authors.initials: J
authors.lastname: Büchs
mesh_terms: D018533:Biomass; D019149:Bioreactors; D018929:Cell Culture Techniques / Q000295:instrumentation / Q000379:methods*; D058266:Dielectric Spectroscopy / Q000295:instrumentation / Q000379:methods*; D004553:Electric Conductivity; D004867:Equipment Design; D005285:Fermentation; D057166:High-Throughput Screening Assays; D010843:Pichia / Q000378:metabolism; D015203:Reproducibility of Results
keywords: Biomass determination; High-throughput system; Impedance spectroscopy; Microtiter plate; Online-monitoring