## 3 Results
vulgaris_ EO showed a good, but different, inhibitory effect vs both bacterial and fungal colonies; MBC/MFC values measured are closely related to phenolic compounds [48; 51; 52]. A reduced variance was revealed, which could be related to different factors, such as oil solubility or the different susceptibility of the microbes to the substances, because all microbes present differences in cell wall structure, lipid and protein composition of the cytoplasmic membrane, as well as in specific physiological processes. The values of inhibition halos (mm) in Table 1 were derived from ADD and WPD assays, performed in duplicate for each antimicrobial and control solution. A variable activity of EO and HA solutions was distinguished, and attributable to the different concentrations of chemical compounds such as carvacrol and thymol. Furthermore, different activity on microbial systems could be related to difference on cell wall structures, lipid/protein composition of cytoplasmic membranes, and to potential influence on specific physiological processes [53; 54; 55]. A survey to assess possible changes pre- and post-removal by HA solution application was carried out, performing colorimetric measurement on selected points of the artwork's surface (Figure 5). The \(\Delta\)E results were lower than 4.0 (3.821 on the lighter area and 2.75 on the darker area, respectively), corresponding to a variation not perceptible by the human eye, as shown in Figure 6. The measurement did not show any significant variation in all three parameters (L*, a*, b*), both on the darkened (surface) and lighter (lacuna) areas. Figure 5: Selected area of the wood sculpture surface pre- (**a**) and post- (**b**) microbial colony removal by the _T. vulgaris_ hydro-alcoholic solution. Notable is the complete removal of whitish spots and any distinguishable change in color in the brownish and light areas (lacuna) respectively. Removal action by HA solution, was preceded by FTIR and ESEM-EDS analyses of the wooden sculpture's surface, in order to exclude the presence of binder or finishing layers. As seen in Figure 6a, the FTIR spectrum revealed a silico-aluminous layer classified  
Figure 6: Evaluation of potential changes on the artwork’s surface pre- and post- treatment, respectively: (**a**) comparison of FTIR spectra; ESEM-EDS analysis pre (**b**) and post treatment (**c**). as a soiled contaminant due to conservation conditions, identified by the highlighted peaks. Furthermore, an E-SEM analysis of the wood surface was performed, pre- and post-treatment by the HA solution, and any changes have been highlighted (Figure 6b,c). Particularly E-SEM images showed no increase in fractures or changes in the elemental composition of the surface. To test the hypothesis that the antimicrobial efficiency of _T. vulgaris_ extracts can be implemented performing a cooperative action of EO exposure and HA solutions, a dedicated \"clean chamber\" was assembled. Specifically, after the microbial colonies' removal by the HA solution, the wooden artwork was exposed to EO volatile compounds (Figure 7). During the seven weeks of permanence in the \"clean chamber\", a monitoring of microbial colonization was carried out weekly. Sampling on the selected surface areas was performed with sterile swabs, utilized to inoculate nutrient and Sabouraud agar media in an in vitro microbial culture. The monitoring continued for another ten weeks, after which the artifact was brought back to the museum's exhibition hall. Results of the microbial growth monitoring, performed for total of seventeen weeks, are shown in Figure 8a,b, evaluating the total microbial load (TML). In the first seven weeks: (a) TML initially revealed on artwork's surface (black line), slightly decreased after exposure to EO volatile compounds (orange line).