Real‐time dissolved carbon dioxide monitoring II: Surface aeration intensification for efficient CO2 removal in shake flasks and mini‐bioreactors leads to superior growth and recombinant protein yields

• Published in: Biotechnology and bioengineering Vol. 117; no. 4; pp. 992 - 998
• Main Authors: Chopda, Viki R., Holzberg, Timothy, Ge, Xudong, Folio, Brandon, Wong, Lynn, Tolosa, Michael, Kostov, Yordan, Tolosa, Leah, Rao, Govind
• Format: Journal Article
• Language: English
• Published: New York Wiley Subscription Services, Inc 01-04-2020; John Wiley and Sons Inc
• Subjects: Aeration; Bioreactors; Carbon dioxide; Cell culture; dissolved carbon dioxide; Flasks; Headspace; Low level; Mass transfer; mini‐bioreactor; Monitoring; Proteins; shake flasks; Sparging; surface aeration intensification
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.27252

Mass transfer is known to play a critical role in bioprocess performance and henceforth monitoring dissolved O2 (DO) and dissolved CO2 (dCO2) is of paramount importance. At bioreactor level these parameters can be monitored online and can be controlled by sparging air/oxygen or stirrer speed. However, traditional small‐scale systems such as shake flasks lack real time monitoring and also employ only surface aeration with additional diffusion limitations imposed by the culture plug. Here we present implementation of intensifying surface aeration by sparging air in the headspace of the reaction vessel and real‐time monitoring of DO and dCO2 in the bioprocesses to evaluate the impact of intensified surface aeration. We observed that sparging air in the headspace allowed us to keep dCO2 at low level, which significantly improved not only biomass growth but also protein yield. We expect that implementing such controlled smart shake flasks can minimize the process development gap which currently exists in shake flask level and bioreactor level results.
Surface aeration intensification was implemented in shake flasks enabled with in house developed monitoring sensors for pH, dissolved oxygen and dissolved CO2. Efficient removal of CO2 from the shake flasks and enhanced O2 supply resulted in increased biomass growth and protein yield. Improved surface aeration in shake flasks can translate into better scale down models and smoother scale up activities, and thus will bridge the gap that exists in process development.