Cultivation of CR.pIX cells in 1 L stirred tank reactor. A: viable cell concentration (■) and viability (●) with the time frame used for MFA indicated by a pale blue box. Bands around data points indicate standard deviation from triplicate measurements. B: extracellular concentrations glucose (■) and lactate (♦); C: extracellular concentrations of glutamine (▲) and ammonia (►). Bands around data points indicate measurement errors from assay validations (see Additional file 1: Table S3).