Fig. 2

The tri-stable-switch circuit was efficient under a range of pH values in vitro. a The pH variation (mean ± S.E.M.) that occurred within bacterial cultures during 12 h of growth under different initial pH conditions. b The β-galactosidase (β-GAL) activity (mean ± S.E.M.) that occurred within bacterial cultures grown for 12 h under different initial pH conditions. c The L-lactate dehydrogenase (L-LDH) activity (mean ± S.E.M.) within bacterial cultures that were grown for 12 h under different initial pH conditions. In all panels, the control culture (BL21: pETDuet1-0) is colored in orange, while the test culture (BL21: pETDuet1-1) is colored in blue. All of the data were produced using three parallel experiments