Fig. 6

Two-stage glycerol feeding strategy cultivation of E. coli and production of soluble recombinant γ-CGTase. a The DCW achieved in the absence of cyclodextrin; b the DCW achieved in the presence of β-cyclodextrin; c the soluble γ-CGTase activity obtained in the absence of β-cyclodextrin; and d the soluble γ-CGTase activity achieved in the presence of β-cyclodextrin. Curves represent lactose feeding rates of 0.15 g·L^− 1·h^− 1 (triangle), 0.30 g·L^− 1·h^− 1 (square) and 0.60 g·L^− 1·h^− 1 (circle). The solid plot symbols represent the DCW and total soluble γ-CGTase activity, while the hollow symbols represent the extracellular γ-CGTase activity. CD, cyclodextrin; DCW, dry cell weight. The results were obtained from three independent experiments