E. Attachment of Fn 12230 grown to log or stationary phase to CRC cells DLD1. Fn 12230 (Fn) was either unwashed or washed twice with PBS or 1 mg/ml Congo Red (CR), or mixed with 20 μl mAb 7H7, before adding to the monolayers at multiplicity of infection (MOI) of 50:1. US1 (∆fadA) was included as a negative control. The attachment level by untreated log phase Fn was designated as 100%, which all other values were expressed relative to. Data shown are mean values ± SEM. The experiment was performed in duplicate and repeated four times. *p < 0.05, **p < 0.01, ***p < 0.001 (t-test). 