# Eco-Friendly Preservation of Pharaonic Wooden Artifacts using Natural Green Products
## 4 Discussion  
Treating and preserving archaeological wood against microbial deterioration with natural and low-cost compounds is a challenge to prevent damage from microbial attack and, at the same time, there is an urgent need to find products that are safe for the health of conservators and museum staff [9]. The appearance of isolated fungal species may be attributed to their cellulase activities on the tested wooden objects, as suggested by [PERSON] et al. [48]. The results obtained in this study are in accordance with [PERSON] et al. [49] who isolated _Aspergillus flavus_, _A. fumigatus_, _A. niger_, _A. terreus_, and _Penicillium chrysogenum_ from a Nabataean wooden coffin in Jordon. Most of these fungi produce cellulases, which degrade the cellulose content of the wood; in addition, fungal decay causes a significant reduction in the strength of the wood and changes its morphological aspect. The most frequently and deterioration-causing fungi found in the current study (_Aspergillus flavus_, _A. fumigatus_, _A. niger_, and _A. terreus_) are similar to those found by other authors. Moreover, [PERSON] et al. [50] isolated _A. flavus_, _A. versicolor_, and _Cladosporium_ sp. from a wooden offering table dating back to the Middle Kingdom period in Dahshur necropolis located in the desert on the west bank of the Nile, Giza, Egypt. In addition, _Aspergillus flavus_ and _A. niger_ were isolated from ancient funeral masks in Saqqara, Egypt, which revealed various aspects of deterioration (discoloration, cracks, and stains) [51]. _Cladosporium_, _Phoma_, and _Ullocalium_ have a black pigment (melanin) that causes distinct dark grey discoloration on wood joints [27]. In the present work, _Aspergillus_ was the most dominant genera isolated from the ten tested archaeological objects, with 322 colonies (8 species) that represent 54% of the total fungal colonies, followed by _Penicilli_ with 98 colonies (5 species) representing 16.4% of the total fungal colonies. The obtained data are in agreement with [PERSON] et al. [52], who found that the most dominant genera isolated from the storage area of [PERSON]'s solar boat and wooden frames of the Stucco window in the Islamic Art Museum were _Aspergillus_ spp.b and _Penicillium_ spp. In particular, species of the genus _Aspergillus_ (an _Ascomycota_ in the brown rot fungi group) were as also found by [PERSON] et al. [52] who isolated and identified different species of white, brown, and soft rot fungi in the structural woods of eight historical churches in  
Figure 7: XRD patterns of the experimental wood samples. The XRD patterns were recorded in a 20 diffraction angle range from 2\({}^{\circ}\) to 40\({}^{\circ}\). (**a**) _Acacia nilolica_ standard wood; (**b**) thyme oil-untreated wood. (**c**) Wood sample treated with thyme oil. The 101 and 200 (red lines) are the diffraction peak intensities pertaining to crystalline cellulose. Chile, causing decay in these historical buildings. _Aspergillus flavus_ (14.6%) was the most frequently isolated fungal species recovered from all the archaeological wooden objects studied here, accounting for 87 colonies. This is in line with the fact that it can produce a wide range of hydrolytic enzymes, facilitating the penetration and breaking down of different organic substrates [53]. _A. flavus_ can also develop on protein substrates (mucin and elastin) on complex carbohydrate substrates such as wood components (cellulose, pectin, chitin, and xylan) [54]. The second dominant fungal species was _Aspergillus niger_ (13.8%) with 82 colonies. The high biodeterioration power of _A. niger_ in terms of the cultural heritage is attributed to its great enzymatic activities as found by [PERSON] et al. [55] and [PERSON] et al. [56]; in fact, it can be adapted to different environmental conditions by different metabolic mechanisms [57]. The degradation action of _A. niger_ is performed by the production of pectinases, hemicellulases, and xylanases [58].