# Chemical Composition and Biological Activities of Oregon and Lavender Essential Oils
## 3 Results
### TEM (Transmission Electron Microscopy) Observation  
Under TEM microscope, untreated samples appeared as typically rod-shaped cells (Figure 2a,b), delimited by a well visible, typically smooth, and multi-layered surface (Figure 2b,c). The protoplast has a normal grainy appearance, more electron-dense in the periphery and more clear in the center (Figure 2b,c). Differently, oregano and lavender  
\begin{table}
\begin{tabular}{c c c c c} \hline \multicolumn{4}{c}{_O. glandulosum_} & \multicolumn{4}{c}{_L. dentata_} \\ \hline
**Inhibition Zone** & **MIC** & **MBC** & **Inhibition Zone** & **MIC** & **MBC** \\ \hline
43.5 \(\pm\) 6.7 & 5.2 \(\pm\) 3.3 & 7.4 \(\pm\) 5.1 & 9.3 \(\pm\) 0.9 & 40.6 \(\pm\) 25.5 & 48.1 \(\pm\) 25.7 \\ \hline \end{tabular}
\end{table}
Table 2: The table shows the inhibition haloes, expressed as mm, and MIC and MBC values, expresses as mg/mL, obtained with _O. glandulosum_ and _L. dentata_ essential oils tested against ESBL _K. pneumoniae_ strains.  
Figure 1: Inhibition halo of the _L. dentata_ and _O. glandulosum_ on activity against specific ESBL _K. pneumoniae_ strains, by disc diffusion method observed at the MIC values.  
essential oil-treated cells lost the typical rod shape and appear globular (Figure 2d-f). The protoplast is not grainy but shows large electron dense areas (Figure 2d-f). The cell surface developed bulges and external curly filaments (Figure 2d-f). At higher magnification, the bulges can appear as dilation of the outer membrane, while the inner one and the wall maintain their continuity (arrow in Figure 2e).  
Figure 2: The figure shows TEM micrographs of untreated _K. pneumoniae_ samples (**a–c**) and _K. pneumoniae_ treated with _O. glandulosum_ (**d,e**) and _L. dentata_ (**f**) essential oil at the mean MIC value. (**a**) Three typical rod-shaped cells. Those lined up are still dividing. (**b**) A bacterial cell taken at higher magnification shows the grainy protoplast delimited by a smooth external cell wall. (**c**) Detail of a bacterial cell shows the grainy protoplast and the multi-layered surface, taken at higher magnification. (**d**) A O. glandulosum essential oil-treated bacterial cell with a globular-shape appearance. The protoplast, not grainy, is electron dense in large areas. The surface developed large bulges and an external hairy material. (**e**) Details of the altered cell taken at higher magnification. The arrow shows the continuity of the inner membrane and the cell wall. (**f**) Bacterial cells treated with _L. dentata_ essential oil. The protoplast, with no grainy appearance, appears moderately dense in large areas. Scale bars: 500 nm (**a,f**); 300 nm (**b,d**); 200 nm (**c,e**).  
\begin{table}
\begin{tabular}{c c} \hline \hline  & **Absorbance (260 nm)** \\ \hline Control & 0.003 \(\pm\) 0.001 a \\ \hline _O. glandulosum_ & 1.466 \(\pm\) 0.048 b \\ \hline _L. dentata_ & 1.345 \(\pm\) 0.048 c \\ \hline \hline \end{tabular}
\end{table}
Table 3: Effect of essential oils from _L. dentata_ and _O. glandulosum_, tested at MIC values (40.6 mg/mL of _L. dentata_ EO; 5.2 mg/mL of _O. glandulosum_ EO) on the release of the 260 nm absorbent material from ESBL _K. pneumoniae_. Lower case letters denote significant difference at \(p\) < 0.05 between samples.