Morphological and viability changes in Escherichia coli and E. coli O157:H7 cells upon rapid shift from 6 °C to 37 °C

► Escherichia coli O157:H7 produced elongated and filamentous cells at 6 °C. ► Time at 6 °C did not affect lag phase of E. coli upon transfer to 37 °C. ► Cells not elongated at 6 °C were inactivated when transferred to 37 °C. ► Shift of elongated E. coli from 6 °C to 37 °C yielded multiple daughter cells. ► Physiological effect of 6 °C incubation not resolved by single replication at 37 °C.