# Current Knowledge on the Fungal Degradation Abilities
## 2 Calcium Carbonate Solubilization or Dissolution  
One of the greatest fungal effects on stone monuments is credited to their secretion of inorganic and organic acids that can alter the material properties [2; 3; 4; 29; 30; 31; 32]. In fact, carbonate weathering has been consistently linked to the excretion and action of these metabolites [33; 34; 35]. Evaluation of fungal calcium carbonate solubilization abilities in cultural heritage scenarios has been helpful to study the biodeteriorative contribution of isolates retrieved from air, mural paintings, wooden art objects, frescoes, catacombs, bricks, concrete, buildings and various limestone and plaster monuments and museums [28; 33; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44]. Fungal calcium carbonate solubilization ability screening is usually conducted with CaCO\({}_{3}\) glucose agar and adapted formulations [33]. Nonetheless, the application of Malt extract agar and Reasoner's 2A agar amended with CaCO\({}_{3}\) (CMEA and CR2A) has also been successfully achieved [35]. Moreover, [PERSON] and colleagues [37] also highlighted the utility of Glucose Yeast extract calcium carbonate agar (GYC) [45] for such evaluation. Positive CaCO\({}_{3}\) dissolution is usually evaluated by the visualization of a halo around the growing colony after a period of incubation. In addition, calcium carbonate solubilization screening can also be conducted coupled with the evaluation of the media pH modifications. For this purpose, Creatine Sucrose agar (CREA) [46] followed by the analysis of medium color changes around growing colonies, or liquid media according to the formulations provided by [PERSON] and colleagues [47] followed by pH analysis, can also be applied. A quick overview of the known fungal species able of CaCO\({}_{3}\) dissolution points that isolates from more than fifty species have been found to display this biodeteriorative profile, with the great majority of them being _Aspergillus_ and _Penicillium_ species (Table 1). Both genera are known important biodeteriorogens, producing various acidic molecules and contributing to the deterioration of materials [28; 48]. The detection of species from these genera (as well as others for example, from _Pestalotiopsis_ and _Talaronyces_ among others) might indicate a putative threat to acid susceptible resources, such is the case of stone structures, mural paintings and frescoes. \begin{table}
\begin{tabular}{c c c} \hline
**Current Species Name** & **Original Study Focus** & **References** \\ \hline _Accennium charticola_ (Lindau) [PERSON] & Limestone and plaster monuments and museums & [39] \\ _Actinmotor elegans_ ([PERSON]) [PERSON] & Mural paintings & [41] \\ _Alternaria alternaria_ (Fr.) [PERSON]. & Mural paintings & [41] \\ _Annulohypoxylon stytium_ ([PERSON].) [PERSON], [PERSON] and & Mayan buildings & [35] \\ [PERSON] & Wooden art objects & [36] \\ _Aspergillus anstelodami_ ([PERSON]) [PERSON] & Wooden art objects & [36] \\ _Aspergillus avamori_ [PERSON]. & Wooden art objects & [36] \\ _Aspergillus europaeus_ [PERSON], [PERSON], [PERSON], & Frescoes and air & [38] \\ [PERSON], [PERSON] and [PERSON] & & \\ _Aspergillus glaucus_ ([PERSON] [PERSON] & Limestone tomb & [43] \\ _Aspergillus nidulans_ ([PERSON]) [PERSON] & Mural paintings & [41] \\ _Aspergillus niger_ [PERSON] & Wooden art objects, frescoes, air, brick and concrete & [28; 36; 38; 40] \\ _Aspergillus versicolor_ ([PERSON].[PERSON] & Wooden art objects, mural paintings, limestone, & [36; 39; 41] \\ \hline \end{tabular}
\end{table} 
Table 1: Overview of fungal species for which isolates have been identified as having CaCO\({}_{3}\) dissolution abilities in biodeteriorative plate essays.