Analysis of biofilm growth
Crystal violet staining was performed as described previously (McAuliffe et al., 2006). Biofilms grown on glass coverslips and in microtitre plates were rinsed briefly in PBS to remove non-adherent cells and stained with 0.5% crystal violet solution for 30 min. Biofilms were then washed profusely in dH2O before being left to dry at room temperature for 30 min. Coverslips were broken into smaller pieces using sterile forceps and 1 ml 100% ethanol was added to solubilize the crystal violet. Solubilization of the crystal violet in stained biofilms was implemented by adding 200 ml of 100% ethanol onto the microtitre plates. Biofilm production was quantified by measuring the absorbance (560 nm) of 100 ml of the solubilized crystal violet in a microtitre plate.