Expression of 27.5 kDa soluble recombinant protein (marked by arrow). Expression is similar for LB and minimal medium for shake flask cultures and the same induction time. Fermenter cultivation allows a higher expression level due to longer induction time. Soluble cell fractions were prepared by chemical/enzymatic lysis. Induction 40 μM IPTG at 20°. Lane 1. SeePlus 2+ MW ladder. Lane 2. Shake flask LB, time after induction 17 h. Lane 3. Shake flask, minimal medium, time after induction 17 h. Lane 4. Fermenter 2H, 15N 5-litre scale fermentation, minimal medium, time after induction 40 h.