AUTOMATIC-CONTROL OF MICROPROPAGATION MEDIUM SUCROSE CONCENTRATION

A whole plant liquid/membrane micropropagation bioreactor system was m odified to allow the culture process to operate semicontinuously. The medium composition control (MCC) system allowed bioreactor medium to b e sampled automatically at 3-h intervals and an aliquot analyzed for s ucrose and dextrose concentration. Data obtained were used as the inpu t to a three-state on/off control system which maintained medium sucro se within a preset threshold of +5% of the desired concentration and m edium volume levels within a +2.5% threshold. The MCC system performan ce testing, without explant tissue, showed it to respond within these design limits when disturbances and setpoint changes were imposed on t he system. Stage I Nicotiana tabacum (tobacco) explants cultured in th e MCC system were found to have both large fresh weight gains and prol ific shoot production. The MCC-grown explants showed increased tissue fresh weight gains over previous bioreactor studies including treatmen ts on conventional agar-based medium, on static-liquid medium, in a li quid/membrane bioreactor with seven-day fresh medium replacement and i n a liquid/membrane bioreactor equipped for monitoring sucrose concent rations.