FIG 6.

Contribution of Cah to attachment of E. coli O157:H7 to spinach leaves. Bacterial adhesion to baby spinach leaves was assessed in STEC strains EDL933 (A) and SS17 (B). The population of attached STEC cells on spinach leaves was expressed in CFU per disc. Strain MQC966 is strain EDL933 transformed with the expression vector pBBR1MCS and served as the control strain. Strain MQC1048 is strain EDL933Δcah transformed with the expression vector pBBR1MCS. Strain MQC1050 is the EDL933Δcah-transformed cloned strain EDL933 cah. Strain MQC928 is strain SS17 transformed with the expression vector pBBR1MCS and served as the control strain. Strain MQC930 is strain SS17 transformed with the cloned EDL933 cah, and strain MQC932 is strain SS17 transformed with cloned SS17 cah (Table 2). Each bar represents the average number of attached cells and SEM from two discs of tissue per leaf and from four leaves. **, P < 0.001 (indicating significant differences in the means between the two strains by Tukey's multiple-comparison test).