Description
For the microarray experiments, 10 g glass wool (Corning Glass Works, Corning, N.Y.) were used to form biofilms (30) in 250 mL in 1 L Erlenmeyer shake flasks which were inoculated with overnight cultures diluted that were 1:100. For EHEC with 7-hydroxyindole and isatin, 1000 mM 7-hydroxyindole in 250 mL DMF, 250 mM isatin in 250 mL DMF, or 250 mL DMF alone were added to cells grown in LB. The cells were shaken at 250 rpm and 30C for 7 hours to form biofilms on the glass wool, and RNA was isolated from the suspension cells and the biofilm.