ANTIBACTERIAL PROPERTIES OF COMMERCIAL GERANIUM ESSENTIAL OIL AGAINST SOME GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA

Purpose: The purpose of the study was to evaluate the antibacterial properties of commercial geranium essential oil (Etja, Elbląg, Poland) against some Gram-positive and Gram-negative bacteria. To this intent, the antimicrobial susceptibility test was used (the Kirby–Bauer disk diffusion test for measuring zone diameters of bacterial growth inhibition). Methodology. Natural geranium essential oil (Etja, Elbląg, Poland) was used in the current study. The testing of the antibacterial activity of geranium essential oil was carried out in vitro by the Kirby-Bauer disc diffusion technique. In the current study, Gram-positive strains such as Enterococcus faecalis (Andrewes and Horder) Schleifer and Kilpper-Balz (ATCC® 51299™) (resistant to vancomycin; sensitive to teicoplanin), Enterococcus faecalis (Andrewes and Horder) Schleifer and Kilpper-Balz (ATCC® 29212™), Staphylococcus aureus subsp. aureus Rosenbach (ATCC® 29213™), Staphylococcus aureus subsp. aureus Rosenbach (ATCC® 25923™), Staphylococcus aureus (NCTC 12493™), and Gram-negative strains such as Pseudomonas aeruginosa (Schroeter) Migula (ATCC® 27853™), Escherichia coli (Migula) Castellani and Chalmers (ATCC® 25922™), and Escherichia coli (Migula) Castellani and Chalmers (ATCC® 35218™) strains were used for the assessment of antibacterial activity of geranium essential oil. Scientific novelty. The highest diameters of the inhibition zone around the growth of Gram-negative strains were obtained for Escherichia coli (Migula) Castellani and Chalmers (ATCC® 25922™) and E. coli (Migula) Castellani and Chalmers (ATCC® 35218™) strains. Diameters of the inhibition zone were increased by 47.6% (p < 0.05) and 84.1% (p < 0.05) compared to the control samples, respectively. Gram-positive strains were more sensitive to the impact of commercial geranium essential oil. The highest diameters of the inhibition zone around the growth of Gram-positive strains were obtained for Staphylococcus aureus subsp. aureus Rosenbach (ATCC® 29213™) and Staphylococcus aureus subsp. aureus Rosenbach (ATCC® 25923™). Diameters of the inhibition zone were increased by 95.1% (p < 0.05) and 67.7% (p < 0.05) compared to the control samples, respectively. Conclusions. This study demonstrated that commercial geranium essential oil possesses potential antimicrobial properties against Gram-positive bacteria, such as Enterococcus faecalis (Andrewes and Horder) Schleifer and Kilpper-Balz (ATCC® 51299™) and Enterococcus faecalis (Andrewes and Horder) Schleifer and Kilpper-Balz (ATCC® 29212™), S. aureus subsp. aureus Rosenbach (ATCC® 29213™) and S. aureus subsp. aureus Rosenbach (ATCC® 25923™) strains. Pseudomonas aeruginosa strain was resistant to commercial geranium essential oil. This study showed that this essential oil could be a potential preparation as a source of natural antibacterial properties.