Fig. 5.

Growth of E. coli BL21(DE3) [pET29a(+)+V-atp] and E. coli BL21(DE3) [pET29a(+)] in M9 media at different pH. In all, 0.3 ml of the mother culture with an OD₆₀₀ of ~1.8 was inoculated into 100 ml of M9 medium with 50 μg ml⁻¹ kanamycin and 0.25 mM IPTG at pH 4.2 (a), 4.5 (b), 5.0 (c), and 7.0 (d), respectively, and incubated at 37 °C with shaking at 200 rpm. Growth of E. coli and media pH were determined at ~2-h intervals. Error bars represent the standard errors of triplicate incubations. Error bars smaller than symbols are not shown.