FIG. 1.

PCR/RFLP typing of genes of the Stx1 family. PCR amplification of Stx1 family genes with primers Stx1com-F and Stx1com-R results in a 282-bp (stx₁, stx_1-O48, stx_1-CB168, and stx_1d) or a 283-bp (stx_1c) fragment. The PCR fragments were digested separately with BstEII (lanes 1 to 3), HaeII (lanes 4 to 6), or PflMI (lanes 7 to 9), yielding RFLP patterns characteristic of stx₁, stx_1c, and stx_1d, respectively (Table 2). Lanes M, molecular size standards; lanes 1, 4, and 7, C600(H19) stx₁ (GenBank accession no. M16625); lanes 2, 5, and 8, DG131/3 stx_1c (GenBank accession no. Z36901); lanes 3, 6, and 9, MHI813 stx_1d (GenBank accession no. AY17085).