A process for the fermentative production of L-amino acids using bacteria, wherein L-proline is added to the fermentation broth as an osmoprotective substance in order to suppress the effects on the cells of the hyperosmotic stress. When the above donor element is brought into contact with a receptor and imagewise irradiated, an image is obtained which is free from contamination by the light-to-heat conversion layer. The vessel comprises a support element below said bottom of the vessel for resting on the support plate, said support element having a coefficient of friction with respect to the support plate low enough to allow the sliding and self-centering of the cooking vessel due to the effect of said lower magnetic coupling member. The driving means move the carrier body in the direction of insertion and the second body in a direction different from the insertion direction. One end of the rotating member is rotatably secured to the dragging member, the other end is rotatably secured to the supporting member.