Tyrosinase production of freshly transformed E. coli JM109 (pMFvpt) during the fed-batch cultivation. Cells were grown at 32°C and induced with 1.25 mM IPTG at an OD600 value of 34. (A) Example of the fed-batch process applied in this study. The time course of the dissolved oxygen (pO2) (blue color), pure oxygen input (red color) and the OD600 values (green color) is shown. The dashed arrow indicates the time when feeding started; the solid arrow indicates the onset of induction. (B) Time-profiles of cell density (OD600) and volumetric activity (U mL-1) of tyrosinase during the fed-batch cultivation. The dashed arrow indicates the time when feeding started, the solid arrow indicates the onset of induction. (C) SDS-PAGE of proteins prepared from extracts of E. coli JM109 (pMFvpt). Samples were taken after 22 h just before induction (lanes 1, 4 and 7), after 28 h (6 h induction, lanes 2, 5 and 8), and after 40 h (18 h induction, lanes 3, 6 and 9). Lanes 1–3, insoluble proteins; Lanes 4–6, soluble proteins; lanes 7–9, total proteins. The arrow indicates the position of tyrosinase in the gel. Molecular weight standards are shown on the left.