Optimisation of a bioreactor culture of the moss Physcomitrella patens for mass production of protoplasts

/ 11 Abstract / 12 / 13 One prerequisite for plant functional genomic projects is the development of a high-throughput transformation platform. As the / 14 moss Physcomitrella patens can be transformed via PEG-mediated DNA-uptake into protoplasts, a semi-continuous bioreactor / 15 culture of this plant was optimised regarding protoplast isolation efficiencies. Under standard conditions protoplast yields were / 16 2.8 /10/mg dry weight. This yield was increased sixfold by supplementation of the medium with 460 mg/l ammonium tartrate. The / 17 same effect was achieved by controlling the pH-value in the bioreactor culture with a setpoint of 4.5. In contrast, pH control with a / 18 setpoint of 7.5 reduced the protoplast yield compared to a culture without pH control to 11%. A semi-continuous culture of / 19 Physcomitrella in a 5-l bioreactor grown at pH 4.5 yielded sufficient cell material for more than 100 transformations per day. / 20 /# 2002 Published by Elsevier Science Ireland Ltd.