B. Inhibition of biofilm formation mediated by detergent-resistant Fn pellets by Congo Red. An aliquot of 10 μg detergent-resistant pellets prepared from Fn 12230 (pellet) was added in 96-well plates in the presence of 0, 10 or 50 µg/ml Congo Red (CR), followed by addition of Fn 12230 and incubated as described above. The results shown are the average of four experiments each performed in duplicate. The error bars indicate SD. A representative image following 72 hours of incubation is shown in the top panel. ** p<0.01, ***p<0.001 (t-test). 