The bioreactor consisted of two compartments, one for the culturing and in situ extraction and the second compartment functioned as water jacket for temperature regulation. The temperature was maintained at 30◦C. The culture chamber had a working volume of 2.5 L and a light path of 0.03 m. The pH of the medium (same as described above but without the addition of Hepes buffer) was controlled at 7.5 by automatically dosing short pulses of carbon dioxide to the cell suspension. The reactor was illuminated from one side with a high-pressure sodium lamp (Philips 400W Master SON-T PIA Green Power). The average light intensity was measured using a PAR 2 quantum sensor (SA-190, Li-cor Biosciences, Lincoln, Nebraska, USA).