# Black Fungi on Stone-Built Heritage: Current Knowledge and Future Outlook
## 3 Mechanisms Involved in the Stone Biodeterioration  
Being well adapted to the stone habitat and being oligotrophic, this group of fungi can often act as pioneer colonizer of the stone. In fact, for their growth it is sufficient to have just a little input of nutrient coming from the surrounding environment (e.g., animal and plant particles, air pollutants, guano droppings, etc.) [81, 82]. Marble exposed to different environments and laboratory experiments demonstrated that black fungi such as _Aureobosidium pullulans_ can be the first colonizer of freshly exposed marble surfaces in outdoor conditions [68, 83]. The presence of a source of organic matter, such as the proximity of plants and trees, can considerably increase the chances of colonization by these fungi and the consequent rate of biodeterioration (Figure 4). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Taxon** & **Strain** & **ITS rDNA** \\ \hline _Aeminium ludgeri_ & E12 & MG938054 \\ _Aeminium ludgeri_ & E16 & MG938061 \\ _Necoatenolostroma_ sp. & CR1 & KY111907 \\ _Constantinomyces_ sp. & CR21 & KY111911 \\ _Pseudauendiiliano globosa_ & DPS10 & MH396690 \\ _Pseudotaenolilina globosa_ & CBS109889 & NR136960 \\ _Pseudotaenolilina globosa_ & CCFEE5734 & KF309976 \\ _Vermiconidia calcicola_ & CBS 140080 & NR_145012 \\ _Vermiconidia calcicola_ & CCFEE 5780 & KP791761 \\ _Vermiconidia flagrans_ & CCFEE 5922 & KP791753 \\ _Coniosporium uncitatum_ & CBS 100219 & AJ244270 \\ _Coniosporium appllinis_ & CBS 100213 & AJ244271 \\ _Coniosporium appllinis_ & CBS 352.97 & NR159787 \\ _Coniosporium appllinis_ & CBS 100216 & AJ244272 \\ _Coniosporium appllinis_ & QIIIa & MH023395 \\ _Lithophila catenulata_ & BJ10118 & JN650519 \\ _Lithophila guttlulata_ & M1 & MW361305 \\ _Lithophila guttlulata_ & CCFEE 5884 & KP791768 \\ _Lithophila guttlulata_ & CCFEE 5907 & KP791773 \\ _Kunfa mediterranea_ & CCFEE 5738 & KP791791 \\ _Kunfa mediterranea_ & CCFEE 6211 & KP791793 \\ _Kunfa uticanti_ & CCFEE 5939 & KP791780 \\ _Kunfa calcarccola_ & SL11033 & JQ354925 \\ _Kunfa calcarccola_ & CGMCC 3.17222 & KP174862 \\ _Kunfa marnoricola_ & CCFEE 5895 & KP791775 \\ _Kunfa marnoricola_ & CCFEE 5716 & KP791786 \\ _Kunfa perforants_ & CBS 885.95 & AJ244230 \\ _Kunfa karalitana_ & CCFEE 5732 & KP791782 \\ _Kunfa karalitana_ & CCFEE 5929 & KP791783 \\ _Kunfa petricola_ & CCFEE 726.95 & KG978746 \\ _Kunfa petricola_ & CBS 600.93 & KC978744 \\ _Kunfa petricola_ & IMI38917 & AJ507323 \\ _Kunfa petricola_ & D1 & JF749183 \\ _Kunfa petricola_ & M4 & FJ556910 \\ _Kunfa_ sp. & QIIa & MH023393 \\ _Kunfa_ sp. & QIIb & MH023394 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Cont. The mechanism of biodeterioration of stone monuments caused by black fungi is not fully understood [16; 84]. The pattern of colonization of black fungi, and in particular of MCF, demonstrate once more that these microorganisms are well adapted to the stone habitat. In fact, they not only grow on the surface of stone, causing an aesthetic alteration due to the presence of melanin in the mycelium and conidia, described as discoloration, black staining, black spots, and black/greyish patinas [9; 20; 85]; but they can also act as true endolithic microorganisms by penetrating into the rocks/stones via intercrystalline spaces or through an active mechanism in which both mechanical and chemical aspects are hypothesized. Microscopic observations show that where they settle is shaped accordingly to the morphology of these fungi (Figure 5). This fact can be explained by a local release of organic acids, followed by a precipitation of mineral phases; this buffer effect may be the reason why these fungi, in contrast to other ubiquitous hyphomyceets, such as _Aspergillus niger_ and _Penicillium_ spp., as reported by [PERSON] and [PERSON] [16], do not show a marked organic acid production in laboratory conditions. However, [PERSON] et al.