Miniature bioreactors for automated high-throughput bioprocess design (HTBD): Reproducibility of parallel fed-batch cultivations with Escherichia coli

To verify the reproducibility of cultivations of Escherichia coli in novel millilitre-scale bioreactors, fully automated fed-batch cultivation was performed in seven parallel-operated mi-scale bioreactors with an initial volume of 10 ml/reactor. The process was automatically controlled by a liquid-handling system responsible for glucose feeding, titration and sampling. Atline analysis (carried out externally of the reaction vessel with a short time delay) comprised automated pH and attenuance measurements. The partial pressure of oxygen (pO₂) was measured online by a novel fluorimetric sensor block measuring the fluorescence lifetime of fluorophors immobilized inside the millilitre-scale bioreactors. Within a process time of 14.6 h, the parallel cultivation yielded a dry cell weight of 36.9 ± 0.9 g·l ^-1. Atline pH measurements were characterized by an S.D. of < 1.1% throughout the process. Computational-fluid-dynamics simulation of single-phase flow yields a mean power input of 21.9 W·l^-1 at an impeller speed of 2800 rev./min corresponding to a power number (N_p) of 3.7.