## 3 Discussion  
In the present study the antibacterial effects of lemongrass EO against three bacterium species associated with PK were investigated. As a superficial skin infection, PK is an easily accessible target for topical medications, and EO-based gels and ointments are potential therapeutic candidates [20]. The 12 EOs for our antibacterial study were chosen based on earlier publications reporting their antibacterial features [21; 22; 23; 24; 25; 26; 27; 28; 29; 30]. No data were  
Figure 5: Antibacterial components in the lemongrass EO used in this study after TLC-DB. (**A**) Plate under UV 254 nm, (**B**) TLC plate after treatment with vanillin–sulfuric acid reagent and documented in visible light, (**C**) TLC-DB assay: bioautograms using _B. thuringiensis_, (**D**) TLC-DB assay: bioautograms using _K. sedentarius_ (bright zones indicate antibacterial effects). Mobile phases: dichloromethane and toluene–ethyl acetate 93.7 (_v/v_). The applied volumes of compounds used were as follows: lemongrass EO—6 \(\mu\)L, cital—4.5 and 6 \(\mu\)L, \(\alpha\)-terpineol—1.5 \(\mu\)L. The stock solutions had concentrations as follows: lemongrass EO—200 mg/mL, cital—20 mg/mL, \(\alpha\)-terpineol—100 mg/mL. Order and quantity of the volatile test materials on each plate were as follows: 1-lemongrass EO (1.2 mg); 2-cital (0.09 mg); 3-cital (0.12 mg); 4-\(\alpha\)-terpineol (0.15 mg). Figure 6: Antibacterial components in the lemongrass EO used in this study after TLC-DB. (**A**) plate under UV 254 nm, (**B**) TLC plate after treatment with vanillin–sulfuric acid reagent and documented in visible light, (**C**) TLC-DB assay: bioautograms using _D. congelensis_ (bright zones indicate antibacterial effects). Mobile phases: dichloromethane and toluene–ethyl acetate 93.7 (_v/v_); 1, 4.5 and 6 \(\mu\)L indicated the applied volumes of the EO and the standards (lemongrass essential oil: 1\(\mu\)L, cital: 4.5 and 6 \(\mu\)L, \(\alpha\)-terpineol: 4.5 \(\mu\)L). The lemongrass essential oil was applied without dilution and the stock solution in the cases of cital and \(\alpha\)-terpineol were 100 mg/mL. Order and quantity of the volatile test materials on each plate were as follows: 1-lemongrass essential oil (undiluted); 2-cital (0.45 mg); 3-cital (0.6 mg); 4-\(\alpha\)-terpineol (0.45 mg). available concerning the sensitivities of the known aetiological agents of PK (_B. thuringiensis, Kytococcus sedentarius_ and _Dermatophilus congolensis_). The results of the drop plate method performed with the three tested bacterium species indicated that although the majority of the 12 EOs were antibacterial, this effect was most pronounced in the cases of lemongrass, cinnamon and thyme (Figure 1). The antibacterial potential of the tested EOs was also supported by the MIC and MBC determinations performed in the macrodilution tests, although there were some discrepancies in their efficacies. This may be due to the differing characteristics of the two test methods. The large inhibition zones (>25 mm) and low MIC values (0.1 mg/mL) recorded here related to thyme EO confirm the findings of previous authors [31]. Its strong antimicrobial effect is attributed to its high phenolic compound content, including thymol and carvacrol, which constitute > 40% of this oil [32]. [PERSON] et al. have previously shown that cinnamon EO was very effective against _B. subtilis_, where the MIC value was 0.10 mg/mL, similarl to our results in the cases of all the tested bacteria [33]. In this case, cinnamaldehyde and eugenol, the major components of cinnamon EO, proved to be responsible for the antibacterial activity [34]. Similar to this recent work, the antibacterial role of one major EO component was demonstrated by our results using lemongrass EO and citral. We have also attributed the bactericidal effects to at least one other lemongrass EO component (\(\alpha\)-terpineol). Further studies are required to clarify the roles of cadinence and calamenene. Altogether, the low inhibitory concentration (0.13 mg/mL) of lemongrass EO against a _Bacillus_ species, _B.