2.4. Enumeration of viable cells

At the end of US-TM treatment, a cell scraper was completely dispersed the biofilm cells from the glass slides to the sterile saline in the culture dish. Both cells and sterile saline in the culture dish were transferred to a sterile beaker followed by adding 100 mL sterile saline. One mL of the sample solution was collected and then properly diluted. The 1 mL of diluted sample solution was transferred to a culture dish followed by pouring 15–20 mL of plate counting agar and incubating at 28 °C for 24 h. The total number of colonies was counted lastly.