The closely related and fully sequenced E. coli strains W3110 and MG1655 represent an excellent test for the accuracy of resequencing technology. Hayashi et al. [13] compared the genome sequences of these two strains and resolved all discrepancies, generating a pair of highly accurate genome sequences. The genome sequence of strain W3110 differs from MG1655 by seven single nucleotide polymorphisms (SNPs), one 2 bp insertion, 12 IS element insertions, one deletion of 6.6 kb, and an inversion of 783.1 kb [13] . A summary of all sequence differ-ences between strain MG1655 and W3110 is presented in Table 1 .