250ml were inoculated with 5ml of preculture and incubated until they reached an OD of 0,5. After centrifugation, the cell pellet was washed with HTP buffer and resuspended in 3ml HTP buffer. In the end, 225µl DMSO was added to an end concenctration of 6-7%. The 50µl aliquots were frozen in N2(l) and stored at -80°C.