Fig. 3

Determination of the requirement of evgS/evgA genes in survival of E. coli O157:H7 strain NADC6564 in highly acidic medium and in NE signaling. The overnight bacterial cultures of parental strain NADC 6564 carrying the cloning vector pACYC177 (NADC 6564/pACYC177), evgS/evgA deletion mutant of NADC 6564 carrying pACYC177 (strain NADC 6662/pACYC177), evgS/evgA deletion mutant complemented with evgS/evgA recombinant plasmid pSM779 (strain NADC 6662/pSM779), and an acid sensitive strain of E. coli O157:H7 carrying pACYC177 (strain NADC 6565/pACYC177) were grown in DMEM medium lacking (green bars) or containing norepinephrine (red bars) were diluted in a phosphate-citrate minimal medium acidified to pH 2.5. After 3 h of incubation, cultures were plated for viable cell count determination (as described in materials and methods) Error bars represent standard deviation of the mean of three independent assays. **** p < 0.0001, * p = 0.033; ** = p = 0.0086