Figure 2

Influence of fed-batch medium composition on oxygen saturation and Fab production. Dissolved oxygen tension (DOT, % of saturation) was measured online during 24 microwell plate expression of Fab fragment F1 in E. coli RV308 in the fed-batch-like EnBase medium. Fab yields in mg per liter of culture were measured by antigen-binding ELISA from cell lysate (periplasmic fraction; in black) and broth supernatant (medium fraction; in grey) at 41 h. a: Cultivation without addition of nutrients at induction; b: Cultivation with addition of complex nutrients and 3 U l^-1 biocatalyst at induction (18 h, indicated by arrows). In each case, Fab yields are shown for cultures with initial biocatalyst concentrations of 0.3, 0.6 and 1.5 U l^-1. Representative DOT graphs are shown from the cultures with initially 0.6 U l^-1 biocatalyst. DOT profiles with initial biocatalyst concentrations of 0.3 and 1.5 U l^-1 were essentially similar to the graphs shown. Standard deviations for the ELISA analysis are shown in Additional file 1.