title: Characterization of oxygen transfer in vertical microbubble columns for aerobic biotechnological processes.
abstract: This paper presents the applicability of a microtechnologically fabricated microbubble column as a screening tool for submerged aerobic cultivation. Bubbles in the range of a few hundred micrometers in diameter were generated at the bottom of an upright-positioned microdevice. The rising bubbles induced the circulation of the liquid and thus enhanced mixing by reducing the diffusion distances and preventing cells from sedimentation. Two differently sized nozzles (21 × 40 µm(2) and 53 × 40 µm(2) in cross-section) were tested. The gas flow rates were adjustable, and the resulting bubble sizes and gas holdups were investigated by image analysis. The microdevice features sensor elements for the real-time online monitoring of optical density and dissolved oxygen. The active aeration of the microdevice allowed for a flexible oxygen supply with mass transfer rates of up to 0.14 s(-1). Slightly higher oxygen mass transfer rates and a better degassing were found for the microbubble column equipped with the smaller nozzle. To validate the applicability of the microbubble column for aerobic submerged cultivation processes, batch cultivations of the model organism Saccharomyces cerevisiae were performed, and the specific growth rate, oxygen uptake rate, and yield coefficient were investigated.
authors.affiliation: Institute of Biochemical Engineering, Technische Universität Braunschweig, Braunschweig, 38106, Germany.
authors.forename: Gena
authors.initials: G
authors.lastname: Peterat
authors.forename: Hannah
authors.initials: H
authors.lastname: Schmolke
authors.forename: Thomas
authors.initials: T
authors.lastname: Lorenz
authors.forename: Andreu
authors.initials: A
authors.lastname: Llobera
authors.forename: Detlev
authors.initials: D
authors.lastname: Rasch
authors.forename: Ala'aldeen T
authors.initials: AT
authors.lastname: Al-Halhouli
authors.forename: Andreas
authors.initials: A
authors.lastname: Dietzel
authors.forename: Stephanus
authors.initials: S
authors.lastname: Büttgenbach
authors.forename: Claus-Peter
authors.initials: CP
authors.lastname: Klages
authors.forename: Rainer
authors.initials: R
authors.lastname: Krull
mesh_terms: D000332:Aerobiosis; D019149:Bioreactors / Q000382:microbiology*; D010100:Oxygen / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D010100:Oxygen
keywords: active aeration; biotechnological application; integrated online analytics; lab-on-a-chip; screening instrument; surface-modified PDMS