After 1, 2, 3, 4, and 5 days, the coupons were
washed in sterile distilled water (500 ml) by gently moving in a circular
motion for 5 s and transferred to 50-ml conical centrifuge tubes containing
30 ml of 0.1% peptone water (PW) and 3 g of sterile glass beads
(425–600 μm diameter; Sigma-Aldrich).