Approximately 106 CFU/ml of P. acnes was seeded
onto 20 ml of tryptic casein soy agar. Various concentrations
of the essential oil samples were prepared
in 95% ethanol and 45 ll amounts were
aseptically impregnated onto 8 mm paper discs in
one application and dried under ambient temperature
for 30 min. Discs containing 45 ll of 95% ethanol
were used as controls. The discs were then
placed on the surface of the seeded agar. The
plates were then incubated at 37 C under anaerobic
conditions for 48 h. Antibacterial activity was
defined by measuring the diameter of the growth
inhibition zone. Each concentration of essential
oils was performed in triplicate.