Growth and kinetic parameters of ajuga hairy root in fed‐batch culture on monosaccharide medium

The batch culture of a transgenic plant, Ajuga hairy root, in sucrose and MS medium exhibited glucose and fructose accumulation with culture time and depletion of phosphate ion after 16 days. The use of a monosaccharide instead of sucrose in fed‐batch culture avoided the difficulty of estimating the concentration of saccharides. Glucose was the most adequate monosaccharide for attaining a high cell mass. In fed‐batch culture using a turbine blade fermentor, 27.2 kg‐dry cell m⁻³ was obtained at 39 days in glucose medium, with the final cell mass and production of 20‐hydroxyecdysone increasing 2.6‐fold and 2.0‐fold, respectively, compared with batch culture results with sucrose in a shake flask. The growth of the hairy root was divided into two phases, an exponential growth phase and linear growth phase. The linear growth phase from 5 through 25 kg‐dry cell m⁻³ predominated over the growth curve. On the basis of the data of the fed‐batch culture with glucose, the cell yield, 0.77 g g⁻¹, and maintenance coefficient, 0.105 g g⁻¹ day⁻¹, for Ajuga hairy root were comparable to those of various calluses. The cell yield of the plant cell was larger than the yields of microorganisms and the maintenance coefficient was smaller.