wPin , biomass specific intracellular product
concentration [mg/g]; wPex , biomass specific
extracellular product concentration [mg/g].
Results and Discussion
The process parameters temperature and ยต are important factors in
bioprocess development and are known to have an impact on leakiness of
different E. coli strains (Table 1). Although conclusive,
mechanistic understanding is still missing. In this study, we performed
characterization of the novel E. coli X-press strain in fed batch
cultivations by investigating the influence of temperature andqS,0 (qS at the beginning
of induction) on growth, productivity, lysis and leakiness, with the aim
of understanding the behavior of the strain and finding a cultivation
strategy that allows the successful control of product location. For
comparison of the X-press strain to a benchmark strain, we choseE. coli BL21(DE3), since it is the most widely used E.
coli strain for recombinant protein production (Jia & Jeon, 2016;
Rosano, Morales, & Ceccarelli, 2019). Three combinations of cultivation
temperature and qS,0 (30/0.25, 25/0.13, 35/0.13)
were first applied using the model protein SpA. The most favorable
production conditions were then tested again with the second model
protein VHH.