The advancement of microbioreactor technology in recent years has transformed early- and mid-stage process development. Their monitoring and control capabilities not only promote the rapid accumulation of process knowledge, but also led to an increased scalability when compared to traditionally used systems such as shake flasks and microtiter plates. This study seeks to establish a framework for the micro-Matrix microbioreactor (Applikon-Biotechnology BV) as process development tool. Using experimental methodologies, the system was initially characterised for oxygen mass transfer and mixing time. A problem specific to pH-controlled small- and benchtop-scale bioreactors was highlighted - the efficient removal of CO2 at the investigated scales caused the pCO2 to drop to 0 mmHg during the cultivation. This was shown to negatively affect the maximum viable cell concentration. Therefore, a combination of matched mixing time and matched CO2 addition profile was proposed as a scale-down criterion between 5 L STR and micro-Matrix. Growth trends, maximum viable cell concentrations, final titre, and glycoprofiles were nearly identical at both scales. The scale-down model was then employed to optimise a bolus feeding regime using response surface methodology, which led to a 25% increase of the space-time yield and the final titre.
1. Understand the methods used for characterisation of microbioreactors
2. Evaluate different methods for scale translation from shaken to stirred bioreactors
3. Learn about application of Design of Experiment methodology for process optimisation