Figure 4.

The number of CFU after a 5-min cold atmospheric plasma (CAP) treatment, a 15-min vitamin C treatment, and the synergistic effect of 15-min vitamin C treatment followed by a 5-min CAP treatment for B. subtilis (A), E. coli (B), P. aeruginosa (C), and S. epidermidis (D). The % of viable bacteria was calculated by dividing the total number of bacteria counted in treated sample with total number of bacteria counted in control. All experiments were performed in biological triplicates, the data represent the mean values ± standard deviation. ^*P < 0.05, n/s is not significant. #, biofilm treated with di-H2O for 15 min; §, biofilm treated for 15 min with di-H2O + 5 min with CAP; &, biofilm treated with vitamin C for 15 min; β, biofilm treated for 15 min with vitamin C + 5 min with CAP.