Chromosomal arrangements of the core genes along each genome in Bacillaceae (left) and Enterobacteriaceae (right). Here, only OGs that are universally conserved in a one-to-one correspondence are connected. Core OGs are colored from red to yellow to green according to the chromosomal positions in the reference genomes (B. subtilis and E. coli), and non-core OGs are drawn in grey. Unique genes in each genome are drawn as short vertical bars. Each chromosome is arranged so that the replication origin is located at the center.