a - This locus is inactive in each group B1 strain
Presence (x) or absence (-) of large structural elements in group B1 strains. Flag-1 & Flag-2 refers to the two flagellar systems found in E. coli. T2SS refers to the second type two secretion system (yghJ-pppA-yghG-gspC-M). ETT1 & ETT2 are the E. coli Type III secretion systems. EHS is the enterohemorrhagic type six secretion system, and ETSS2 is the Escherichia coli type six secretion system.