Biofilms of E. coli O157:H7 were produced on wooden coupons in
M9 medium at 22 °C for 3 days, as described above. Coupons were
rinsed in 500 ml of distilled water for 5 s, immersed in 30 ml of sterile
water, NaOCl (200 μg/ml), or ClO2 (200 μg/ml) solutions in 50-ml centrifuge
tubes for 10 min, and rinsed twice in sterile distilled water
(30 ml) to remove residual sanitizers