PLANT-CELL SUSPENSION-CULTURE IN A BENCH-SCALE FERMENTER WITH A NEWLYDESIGNED MEMBRANE STIRRER FOR BUBBLE-FREE AERATION

In this paper, tests of an optimized membrane-stirrer geometry for bub ble-free aeration of a plant cell suspension culture are described. Ce ll attachment and clogging of a previously described system [Piehl et al. (1988) Appl Microbiol Biotechnol 29:456-461] led to the developmen t of a new stirrer. The volumetric oxygen transfer capacity has been m easured in aqueous medium. The mass transfer coefficient, k(1)a, was 3 .75 h(-1) at 25 degrees C and at a stirrer speed of 34 rpm. The overal l oxygen transfer capacity was investigated with a suspension culture of Aesculus hippocastanum It was shown that the oxygen mass transfer w as sufficient even at the maximum biomass of 10-12 g dry weight/l, whi ch was obtained by using this system. Furthermore, special attention w as given to medium components like C and N sources, to avoid growth li mitation due to a shortage of nutrients.