FIG 1.

Organization of the wb gene clusters in the O1, O2ac, O3, O4, O5, O8, and O12 reference strains. The wb gene clusters are located between the highly conserved gnd and hisI genes (black color). The nucleotide position (in kilobases) is relative to the first nucleotide of the complete sequence submitted to GenBank. The wzm and wzt loci are shown in gray. The O1 reference strain has an additional uge gene, which is not present in the other O1 strains. The O2ac reference strain has a truncated wzt gene because of a frameshift mutation (secondary to the addition of two DNA bases, adenine and cytosine, at nucleotides 324 and 325, respectively), which is not present in the other O2ac strains.