Accumulation of plasmids with mutated sinI in various hosts. SinI methyltransferase was expressed from pSin32. Plasmids were isolated at various intervals and screened (by transformation in McrBC+ and McrBC- hosts) for mutations resulting in loss of function of the enzyme. Error bars represent 95% confidence intervals for the average of 3 independent measurements of mutant plasmid ratios. ANOVA revealed a significance of p < 0.005. Pairwise t-tests of each MDS42pdu-T7 sample were done with the corresponding MDS42-T7 and BL21(DE3)mcrBC sample, respectively. Starting from 10 hours, all MDS42pdu-T7 samples differed significantly from the MDS42-T7 (p < 0.01) or BL21(DE3)mcrBC (p < 0.005) samples.