Figure 5. Absorbance of XTT-assay product.

48-hour P. aeruginosa biofilms, grown on Calgary Biofilm Device, were exposed to the 20 kHz plasma jet for up to 4 minutes. After plasma exposure, bacterial cells were dislodged off the pegs into PBS buffer by sonication. 50 µl aliquots of the recovered bacterial suspensions were then mixed with 50 µl of MHB and 20 µl of XTT stock solution and incubated at 37°C for 5 hours. After incubation, the absorbance at 450 nm was measured to quantify XTT metabolic product, the intensity of which is proportional to the number of viable (respiring) cells. (Each point represents the mean of 3 values ± SE).