Potential autonomous units identified in LAB. Alignment of previously described and newly identified PAUs in L. acidophilus NCFM, L. johnsonii NCC533, Lactococcus lactis ssp. cremoris SK11, and Streptococcus agalactiae NEM316. Elements of the core region are shown as colored arrows: DNA segregation ATPase FtsK, red arrow; replication protein RepA, green arrow; Integrase IntG, pink arrow; conserved hypothetical ORFs, orange and cyan arrows, respectively. Flanking ORFs with predicted functions are displayed in light gray arrows. Different functional classes are indicated by distinct pattern. Adjacent ORFs with no functional characterization are indicated by solid gray arrows. Predicted tRNAs are displayed as vertical cyan boxes. Alignments are centered on the start position of IntG and are drawn to scale (color figure online)