Distribution of matches of length 10 or longer across the first 50 kilobases of the E. coli genome. Starts of individual genes are indicated by the blue crosses along the bottom, and matches to a particular genome are indicated in a line above the crosses in a particular color. The first line above the crosses indicates the coding direction of the proteins: either forward (red) or reverse (green). Names of several genes and operons are indicated at the bottom. Black squares in the bottom portion and cyan triangles in the top portion indicate matches to other portions of the E. coli genome (paralogs) are shown for completeness, but not discussed further in this work. The matching signature peptides and annotations of matched genes are enumerated for B. subtilis (black squares in the top panel) in Additional file 1, and discussed below.