Exposure to high hydrostatic pressure rapidly selects for increased RpoS activity and general stress-resistance in Escherichia coli O157:H7

► Exposure to HHP rapidly selects for increased RpoS activity in E. coli O157:H7. ► Upregulation of RpoS activity correlates with the severity of the HHP selection regimen. ► Acquisition of HHP resistance coincides with increased heat resistance. ► Increased RpoS activity does not stem from mutations in the rpoS locus.