Effect of carbon dioxide and ethylene on berberine production and cell browning in Thalictrum minus cell cultures.

Cultured cells of Thalictrum minus L. (Ranunculaceae), transferred from culture flasks to a bubble column bioreactor, produced little berberine and turned dark brown, even when supplied with sufficient oxygen. This phenomenon was ascribed to the removal of CO2 from the culture medium by bubbling air, and could be reproduced in flask cultures artificially deprived of CO2. The induction of cell browning by exogenously administered ethylene suggested that CO2 probably acts antagonistically against endogenously generated C2H4. The physiological damage caused by forced aeration could be prevented by adding 2 % CO2 to the air in the bioreactor.