title: Correlation between mass transfer coefficient kLa and relevant operating parameters in cylindrical disposable shaken bioreactors on a bench-to-pilot scale.
abstract: BACKGROUND
  Among disposable bioreactor systems, cylindrical orbitally shaken bioreactors show important advantages. They provide a well-defined hydrodynamic flow combined with excellent mixing and oxygen transfer for mammalian and plant cell cultivations. Since there is no known universal correlation between the volumetric mass transfer coefficient for oxygen kLa and relevant operating parameters in such bioreactor systems, the aim of this current study is to experimentally determine a universal kLa correlation.
  
  
  RESULTS
  A Respiration Activity Monitoring System (RAMOS) was used to measure kLa values in cylindrical disposable shaken bioreactors and Buckingham's π-Theorem was applied to define a dimensionless equation for kLa. In this way, a scale- and volume-independent kLa correlation was developed and validated in bioreactors with volumes from 2 L to 200 L. The final correlation was used to calculate cultivation parameters at different scales to allow a sufficient oxygen supply of tobacco BY-2 cell suspension cultures.
  
  
  CONCLUSIONS
  The resulting equation can be universally applied to calculate the mass transfer coefficient for any of seven relevant cultivation parameters such as the reactor diameter, the shaking frequency, the filling volume, the viscosity, the oxygen diffusion coefficient, the gravitational acceleration or the shaking diameter within an accuracy range of +/- 30%. To our knowledge, this is the first kLa correlation that has been defined and validated for the cited bioreactor system on a bench-to-pilot scale.
authors.forename: Wolf
authors.initials: W
authors.lastname: Klöckner
authors.forename: Riad
authors.initials: R
authors.lastname: Gacem
authors.forename: Tibor
authors.initials: T
authors.lastname: Anderlei
authors.forename: Nicole
authors.initials: N
authors.lastname: Raven
authors.forename: Stefan
authors.initials: S
authors.lastname: Schillberg
authors.forename: Clemens
authors.initials: C
authors.lastname: Lattermann
authors.affiliation: AVT, Biochemical Engineering, RWTH Aachen University, Worringerweg 1, Aachen 52074, Germany. Jochen.Buechs@avt.rwth-aachen.de.
authors.forename: Jochen
authors.initials: J
authors.lastname: Büchs