## 3 Results and Discussion
### The Determination of the Fungal Contamination  
The fungal loads and the degree of contamination of the air samples were estimated based on indoor applied standards (Table 1) [71]. The Petri dishes used for the Koch method can be observed in Figure 10.  
[PERSON] et al. [72] proposed standards that characterize the cave's atmosphere based on the identified fungal loads in the air samples. Point AS3 falls into category III (between 150 and 500 CFU m\({}^{-3}\))--threatened by fungi and requires different cave management and controls--while AS1 and AS2 fall into category IV (between 500 and 1000 CFU m\({}^{-3}\))--already affected by fungi as a result of massive visits or spillage--and AS4 falls into category V (above 1000 CFU m\({}^{-3}\))--having irreversible ecological disturbance. _Cladosporium herbarum_ (belonging to the genus _Cladosporium_, phylum _Ascomycota_), _Aspergillus niger_ (belonging to the genus _Aspergillus_, phylum Ascomycota), and _Mortierella hyalina_ (belonging to the genus _Mortierella_, phylum _Mucornycota_) are the fungal species identified in the analyzed isolates. Their abundance varies in the different collection points (Figure 11). _Cladosporium herbarum_ is present in all analyzed collection points, while _Aspergillus niger_ is absent in one wall sample (WS1) and _Mortierella hyalina_ in three wall samples (WS3, WS4, and WS5). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Air Sample** & **Number of Fungal CFU/m\({}^{3}\) of Air** & **Degree of Contamination** \\ \hline AS1 & 892 & High \\ AS2 & 580 & High \\ AS3 & 367 & Medium \\ AS4 & 1102 & High \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Fungal loads in the air in the rupestrian church. All the identified species are frequently reported as cave inhabitants [73; 74; 75; 76]. _Cladosporium herbarum_ is frequently present in the air and wall samples in caves worldwide [73; 77]. _Cladosporium herbarum_ is present in the inside air as well as in the outside air. Usually, its frequency is much higher outside, a fact that makes it one of the most frequent contaminants. _Aspergillus niger_ can be also present in air and wall samples [73; 77]. In contrast to _Cladosporium herbarum_, _Aspergillus niger_ is more frequent in the inside air than the outside [73]. _Mortierella_ species are cosmopolitan fungi frequently recovered from soils where they maintain a saprotrophic lifestyle. They can also be plant pathogens. The species are commonly found in subterranean environments and show metal tolerance. _Mortierella hyalina_ is a root-colonizing fungi, and its presence may be associated with the agricultural fields near the rupestrian church entry. SEM images processed with ImageJ software (Figure 12) reveal the presence of fungal hyphae and spores on and within the matrix of the kaolinite-illite mineral assemblage. This can be attributed to various bio-geological processes (i.e., sedimentary deposition, diagenesis, and mineral alteration). Fungal hyphae can infiltrate sediments, releasing nutrients and forming fungal networks. In environments with clay minerals, fungal activity can contribute to the breakdown of organic matter and the alteration of clay minerals. Figure 11: Identified fungal species in the analyzed rupestrian church in the samples collected from the air and walls and abundance plots of the fungal isolated from each collection point. Figure 10: Petri dishes were used for the fungal load estimation in the associated air by the Koch method for the collection sample points 1 (**a**), 2 (**b**), 3 (**c**), and 4 (**d**). _Aspergillus_ and _Cladosporium_ have been reported as biodeteriogens on objects, monuments, etc., belonging to the cultural patrimony with a natural stone support. Their identification and evaluation of biodeterioration, often materialized by discoloration, pigmented patina, powdering, and dissolution [78; 79], precede restoration and conservation activities.