Fig. 3

The effects of different culture media and different concentrations of IPTG on the production of γ-CGTase-PHA nanogranules by recombinant E. coli BL21 (DE3). a Comparison of cell growth in different shake-flask cultures supplemented with different concentrations of IPTG. b SDS–PAGE analysis of γ-CGTase-PHA beads expressed by recombinant E. coli BL21 (DE3) cultured in different shake-flask cultures supplemented with different concentrations. Lane M, protein ladder; Lanes 1–3, LB medium supplemented with 1 mM, 0.5 mM, 0.2 mM IPTG, respectively; Lanes 2–4, TB medium supplemented with 1 mM, 0.5 mM, or 0.2 mM IPTG, respectively; Lanes 5–7, MM medium supplemented with 1 mM, 0.5 mM, or 0.2 mM IPTG, respectively. c, d Comparison of hydrolysis activities (c) and cyclization activities (d) of γ-CGTase-PHA beads in different shake-flask cultures supplemented with different concentrations of IPTG. e–h Transmission electron microscopy analysis of unmodified E. coli cells (e), recombinant E. coli carrying pCDFD-ABC-cgt cultured in LB (f), TB (g), and MM (h) medium after 0.5 mM IPTG induction