On-Line Monitoring of Biomass Concentration Based on a Capacitance Sensor: Assessing the Methodology for Different Bacteria and Yeast High Cell Density Fed-Batch Cultures

Abstract

-The performance of an in-situ capacitance sensor for on-line monitoring of biomass concentration was evaluated for some of the most important microorganisms in the biotechnology industry: Escherichia coli, Saccharomyces cerevisiae, Pichia pastoris and Bacillus megaterium. A total of 33 batch and fed-batch cultures were carried out in a bench-scale bioreactor and biomass formation trends were followed by dielectric measurements during the growth phase as well as the induction phase, for 5 recombinant E. coli strains. Permittivity measurements and viable cellular concentrations presented a linear correlation for all the studied conditions. In addition, the permittivity signal was further used for inference of the cellular growth rate. The estimated specific growth rates mirrored the main trends of the metabolic states of the different cells and they can be further used for setting-up control strategies in fed-batch cultures.

High level extracellular production of recombinant human interferon alpha 2b in glycoengineeredPichia pastoris:culture medium optimization, high cell density cultivation and biological characterization

“…; Horta et al . ; Mohan and Sivaprakasam ). The probe tip consists of a ceramic portion with two annular rings surrounding it, and produces an electric field at an applied frequency.…”

“…Bioreactor set-up was equipped with a capacitance probe (Aber Instruments, Aberystwyth, UK), for monitoring the VCV of P. pastoris (Wechselberger et al 2013;Horta et al 2015;Mohan and Sivaprakasam 2017). The probe tip consists of a ceramic portion with two annular rings surrounding it, and produces an electric field at an applied frequency.…”

Application of In-Situ and Soft-Sensors for Estimation of Recombinant P. pastoris GS115 Biomass Concentration: A Case Analysis of HBcAg (Mut+) and HBsAg (MutS) Production Processes under Varying Conditions

“…Dielectric properties of the cell suspension, such as capacitance (pF) and permittivity (pF/cm), proportionally relate to viable cell volume. This phenomenon is used by in-situ permittivity sensors [ 26 , 27 ] and Coulter-counters [ 28 , 29 ]. Modern instruments use frequency-scanning techniques in a range from 100 KHz to 20 MHz, capable for cell size and biomass concentration estimation (dielectric spectroscopy).…”

“…Reported measurement ranges are up to 35–155 DCW [ 26 , 30 ] in high cell density cultures. The reported method demonstrates limited applicability in low biomass (<~5–10 g/L [ 29 , 30 ]) and high conductivity conditions [ 12 , 13 ]. In the reported research, linear [ 26 , 29 ] or mixed linear-nonlinear [ 29 ] relationships between DCW and permittivity can be observed for various bacterial and yeast cultures cultivated under varying conditions.…”

“…The reported method demonstrates limited applicability in low biomass (<~5–10 g/L [ 29 , 30 ]) and high conductivity conditions [ 12 , 13 ]. In the reported research, linear [ 26 , 29 ] or mixed linear-nonlinear [ 29 ] relationships between DCW and permittivity can be observed for various bacterial and yeast cultures cultivated under varying conditions. As the permittivity measurement selectively accounts for the viable cell volume (compared to DCW, in which also nonviable cells are counted), it is obvious that under varying process conditions the correlation between permittivity and DCW may differ.…”