Escherichia coli is often a preferred microbial host for the production of therapeutic proteins. At Boehringer Ingelheim (BI), we developed a wide variety of expression tools for E. coli. The established toolbox allows successful expression of diverse and challenging candidate proteins. It includes a set of different bacterial strains, various promoters, and leader peptides. Apart from plasmid-borne expression, the toolbox also comprises the option of genomic integration of the target gene expression cassette and the co-synthesis of helper factors.
Combination of toolbox elements produces a large number of different expression strains and, thus, requires an efficient screening strategy to select candidates for further development. To facilitate high-throughput screening at the early stages of process development, a fully automated bioreactor system with up to 32 parallel operating miniaturized 10-mL stirred-tank reactors was established at BI. Each disposable reactor vessel is equipped with fluorimetric sensors for control of pH and DO. A liquid handling robot enables fully automated inoculation, sampling and optical density at-line measurement as well as intermittent fed-batch operation for individual feed and pH profiles for each reactor.
In experiments comparing different fermentation scales the reproducibility of expression results could be shown. The fermentation screening system represents a powerful platform offering new possibilities to reduce turnaround times and save resources.
An overview of implemented data structure, storage and visualization tools will be presented. In the long run, efficient data handling and interpretation ensures effective process development in a fast-changing environment.