Fig 1.

Spontaneous deletions within the Sp11-Sp12 prophage region of Sakai. Genomic loci of Sp11 (light blue) and Sp12 (light red) are shown. Genes related to prophage regulation (blue), to integration/excision (red), to bacterial host lysis (yellow), and putatively to virulence (green) are marked by triangles. Primer pairs (see Table S1 in the supplemental material) used to estimate the range of deletions are indicated using black arrows. Three different classes of deletions were identified. One included the entire Sp11 prophage (46 kb), while the boundaries of the other two deletion types were not definite (shown by dashed lines). The estimated minimal and maximal sizes of each deletion type are listed. The designated type of deletion and the frequency of observation (indicated in parentheses) among 20 second-crossover isolates are shown to the right of each deletion scheme.