Abstract

This study was designed to explore the in vitro antimicrobial activities of the essential oil derived from Pinus koraiensis Sieb. et Zucc. needles obtained throughout the steam distillation. The antimicrobial effectiveness was estimated by the minimum inhibition concentration (MIC) and minimum bacterial concentration (MBC) determinations on 8 species of bacteria and fungi, as well as the confocal laser scanning on 3 types of bacteria bioflims. It was found that the essential oil had good inhibitory activities against Gram-positive bacteria and fungi rather than Gram-negative bacteria, especially C. albicans, with the lowest MIC (0.780%) and MBC (1.560%) values. The Gram-positive bacteria biofilms were sensitive to the essential oil, whereas not the Gram-negative ones. Besides, there is no linear relationship between inhibition activities and oil concentrations within the bacteria biofilms. Further analysis revealed that the essential oil can prompt the biofilm-surface bacteria to die off or live as plankton, to help the immune system to remove the bacteria. Thus, P. koraiensis needle oil could be judged as a kind of potential agent with antimicrobial activities effectively.

Key words: Pinus koraiensis Sieb. et Zucc. Needles, essential oil, antimicrobial activities, bacterial biofilms, confocal laser scanning.