Fed-batch culture of hairy root using fructose as a carbon source

Repeated-batch and fed-batch cultures using sucrose or fructose as a carbon source were carried out in a bioreactor to attain a high cell density of carrot hairy root. From the batch culture experiment, cell yields for main components in the medium were determined and the composition of the medium was modified. In the case of the repeated-batch culture using sucrose, the concentrations of the medium components were kept almost constant and after 40 d the final cell mass increased two-fold, i.e. 19 g-dry weight/l compared with the batch culture. In the fed-batch culture using sucrose, 17 g-dry weight/l of the hairy root was obtained after 48 d by keeping the conductivity of the culture medium constant. Although the concentrations of the medium components including sucrose were kept almost constant, it was found that fructose and glucose accumulated in the culture medium up to 30 g/l. This accumulation could be avoided by using a monosaccharide, e.g. fructose in a fed-batch culture, and the final biomass concentration reached 30.1 g-dry weight/l after 38 d. This study shows that the plant cell density in the bioreactor can be greatly improved by feeding with a monosaccharide as the carbon source in fed-batch culture.