A. Congo Red depletion assay. Fn 12230 (black), the fadA-deletion mutant US1 (∆fadA) (orange) and the spontaneous lam mutant (blue) (top panel) were grown to different OD600. E. coli MC4100, ∆curli, and ∆csgA (bottom panel) were grown on TSA-blood agar plate at 26oC for 48hr. The bacteria were suspended in PBS to OD600 of 0.5, 1.0, 1.5 and 2.0, followed by incubation in 10 μg/ml Congo Red (CR) for 10 min. After centrifugation, the supernatants were measured at OD500. The results shown are the average of five independent experiments performed in duplicate. The error bars indicate SD. *p<0.05, ** p<0.01, ***p<0.001 (compared to wild type, t-test). 