Figure 7.
Escherichia coli O157:H7 (A) and Salmonella enterica Typhimurium 14028s (B) persistence varies in 3.5- to 4-week-old plants of lettuce genotypes after syringe inoculation. Plants of the lettuce genotypes were grown in pots and then three leaves were infiltrated with bacterial inoculum (1 x 106 CFU/mL) with a needleless syringe. Leaves were surface sterilized after inoculation and serial dilution plating was conducted to quantify the bacterial population in the intercellular space. Three leaves were used for each sample point per genotype. Results are shown as the average of three independent experiments (n = 3 ± standard error). Pairwise mean comparison (bacterial population at day 0 versus day 20) was performed with a two-tail Student’s t-test (ns, not significant, *p < 0.05, **p < 0.01, and ***p < 0.001).