GD1 E. coli proliferate more slowly than either wild-type or ATP synthase mutant E. coli. Overnight cultures of the indicated E. coli strains were adjusted to an optical density (A600 nm) of 0.1 in LB medium containing the appropriate antibiotic. The increase in cell number was assayed over time. Solid grey line with open squares, GD1; dotted grey line with +, AN120 (ATP synthase mutant); solid black line with open squares, OP50; dotted black line with X, AN180 (wild-type parental strain of AN120). Asterisks indicate p-value < 0.05 when compared with A600nm of OP50 culture at the 5 and 25 h time points. Data were subjected to one-way ANOVA with Fisher’s test at a significance level of p < 0.05 at each time point indicated.