Figure 3
Transmission electron microscopic micrographs of three strains of Streptococcus pyogenes treated with or without exposure to carvacrol. (A) Cell morphology of vehicle control (DMSO) (b,b′,b′′), carvacrol at 1/8 × MIC (c,c′,c′′), carvacrol at ¼ × MIC (d,d′,d′′), and carvacrol at ½ × MIC (e,e′,e′′) were compared with untreated bacterial (a,a′,a′′) in BHI media. The exponential phase of S. pyogenes Spy 1558 cells was treated with different concentrations of carvacrol for 16 h. Images were taken at magnifications of × 10,000, × 50,000 and × 100,000 for a,b,c,d,e , a′,b′,c′,d′,e′’ and a′′,b′′,c′′,d′′,e′′, respectively. Arrows indicate dead cell morphologies. MIC minimum inhibitory concentration, BHI brain heart infusion. (B) Percentage of carvacrol-induced morphological damages determined by TEM. An average of 200 cells from two independent experiments were analyzed per each treatment. Morphological changes were quantified as the percentage of ruptured and dead cells to the total cells.
