Growth curve of Escherichia coli BL21-AI transformed with pACYCDuet-1 plasmids expressing recombinant VapB or VapC separately, or VapB and VapC together. E. coli cells carrying the empty vector were grown as control. Cells were grown in LB media at 37°C, with linear shaking (1 mm) for 15 s every 15 min. Arrow indicates expression induction by 1 mM IPTG and 0.5% (w/v) arabinose. Growth curves were initiated by adding three colonies to each well, n = 12 (each replicate consisting of three pooled colonies); error bars are standard error of mean. Results from one representative experiment, out of three with similar results are shown.