Construction of two capsule defective mutants, Δcps and Δwzabc. A. Genetic loci that were deleted in the two mutants ∆wzabc and ∆cps. A portion of the capsule export system within the capsule biosynthesis cluster was deleted in ∆wzabc whereas the entire biosynthesis cluster was deleted in ∆cps. The deletions in both mutants left behind an 81 bp scar region (red box). The triangles indicate the CDSs inside the gene clusters. B. Gel image confirming the deletions in both mutants. Two primer pairs (1 and 2 for ∆wzabc; 3 and 4 for ∆cps) were used to verify the deletions by PCR. The small arrows in part A denote the approximate binding location of the primers used to generate these amplicons. Pairs 1 and 3 were designed to amplify the 5′ and 3′ junctions of the wild-type sequence, respectively, while pairs 2 and 4 were designed such that either the forward or reverse primer from each pair bound inside the scar region. In this way, pairs 1 and 3 will produce a PCR amplicon if the wild-type sequence is still present, whereas pairs 2 and 4 amplify only if the correct target locus has been deleted. The amplicon sizes are: pair 1, 833 bp; pair 2, 741 bp; pair 3; 602 bp; pair 4, 428 bp.