Advancement of the cultivation and upscaling of photoautotrophic suspension cultures using Chenopodium rubrum as a case study

Abstract

Photoautotrophic (PA) suspension cultures combine the advantages of cell suspensions with carbon autotrophy and have been used for various applications including studies on photosynthesis, sugar signal transduction, herbicide action, and stress responses. A major practical drawback is the requirement for elevated CO2, which is typically generated by a buffer system in two-tier flasks that need to be custom made and require time-consuming handling. In this study, we substantially simplified and improved the cultivation of a PA culture of Chenopodium rubrum as a case study in Erlenmeyer flasks shaken in a CO2 enriched photoincubator. Growth rates and photosynthetic activity were found to be comparable to those in two-tier flasks but with the advantage of constant CO2 level throughout the cultivation. In addition, it was possible to establish the cultivation in a commercial laboratory-scale photobioreactor with various options to control and continuously measure the culture conditions and regimes and assess the physiological status. Although the relative biomass yield and photosynthetic performance of the batch cultures was not fully reached, the continuous cultivation system provides a good basis for future scale-up if larger amounts of biomass are needed or to impose specific cultivation regimes in combination with comprehensive online monitoring. The different improvements should contribute to the more widespread use of higher plant PA cultures and also facilitate the cultivation of microalgae.