Fed-batch like cultivation in a micro-bioreactor: screening conditions relevant for Escherichia coli based production processes

OBJECTIVES: Recombinant protein production processes in Escherichia coli are usually operated in fed-batch mode; therefore, the elaboration of a fed-batch cultivation protocol in microtiter plates that allows for screening under production like conditions is particularly appealing. RESULTS: A highly reproducible fed-batch like microtiter plate cultivation protocol for E. coli in a micro-bioreactor system with advanced online monitoring capabilities was developed. A synthetic enzymatic glucose release medium was employed to provide carbon limited growth conditions without external substrate feed and the required buffer capacity to keep the pH value within 7 ± 1. Accurate process design allowed for cultivation up to cell densities of 10 g biomass l(−1) without any limitations in oxygen supply [dissolved oxygen (DO) level above 30 %]. In the micro-bioreactor system (BioLector) online monitoring of cell growth, DO and pH was performed. Furthermore, the influence of the cultivation temperature, the applicability for different host strains as well as the transferability of results to lab-scale bioreactor cultivations was evaluated. CONCLUSION: This robust microtiter plate cultivation protocol allows for screening of E. coli systems under conditions comparable to lab-scale bioreactor cultivations.