# Role of Exposure on the Microbial Consortium on Historical Rural Granite Buildings
## 3 Results and Discussion
### Culture Dependent  
Green algae and cyanobacteria were isolated from the three granite churches using a culture-dependent approach. The species/taxon compositions of the sampled biofilms are shown in Table 1 and the most representative species are shown in Figure 2. Four species (_Trentepohlia_ cf. _umbrina_, _Desmococcus olivaccus_, _Tychonema_ cf. _bourrellyi_, and _Phormidium autumnale_) predominated in the churches, although differences in the abundance of the species were observed in the three churches and on the N- and W-facing walls of the same church. The N-facing walls of the SMV and BAR churches were dominated by _Trentepohlia_ cf. _umbrina_, while the W-facing walls were predominated by _Desmococcus olivaccus_ (Figure 3). In the ROC church, the cyanobacteria _Tychonema_ cf. _bourrellyi_ and _Phormidium autumnale_ predominated on the W-facing wall, with a minor presence of _Desmococcus olivaccus_. Green algae (Chlorophyta) and cyanobacteria were similarly represented on the N-facing wall, with _Desmococcus olivaccus and Phormidium autumnale_ predominating. Thus, the microbial communities on the SMV and BAR churches were similar to each other, but different from those on the ROC church (Figure 4). The biofilms on the first two churches were mainly composed of green algae, while biofilms on the ROC church contained a higher percentage of cyanobacteria, especially on the W-facing wall. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Species**} & \multicolumn{4}{c}{**NORTH**} & \multicolumn{4}{c}{**WEST**} \\ \cline{2-7}  & **SMV** & **BAR** & **ROC** & **SMV** & **BAR** & **ROC** \\ \hline _Trentepohlia cf. umbrina_ & Chl & 80 & 75 & & 10 & 23 & \\ \hline _Desmococcus olivaccus_ & Chl & 9 & 10 & 53 & 81 & 71 & 15 \\ \hline _Phormidium autumnale_ & Cy & & 1 & 40 & & 30 \\ \hline _Tychonema cf. bourrellyi_ & Cy & 1 & & & & 50 \\ \hline _Bractaecoccus minor_ & Chl & 1 & & 1 & & \\ \hline _Chlamydomonas sp. sensulato_ & Chl & & 1 & & & \\ \hline _Cococomyza confluens_ & Chl & 1 & & 1 & 1 & 1 & \\ \hline _Cocenochloris signiensis_ & Chl & 1 & 1 & & & \\ \hline _Dictyosphaerium chlorelloides_ & Chl & & 1 & & & \\ \hline _Diplosphaerachodati_ & Chl & 1 & 1 & 1 & 1 & 1 & \\ \hline _Elakatothrix gelatinosa_ & Chl & & 1 & & & \\ \hline _Cylindrocystis brebissoni_ & Chl & & 1 & & & \\ \hline _Ellipochloris sp._ & Chl & 1 & 1 & 1 & 1 & 1 & 1 \\ \hline _Gloecystispoly dermatica_ & Chl & 1 & 1 & & & \\ \hline _Hantzschia amplpyaxis_ & Ba & & 1 & & & \\ \hline _Klebsormidium cf. flacidium_ & Chl & 1 & 1 & 1 & 1 & 1 & 1 \\ \hline _Mesotaenium cf. caldariorum_ & Chl & & 1 & & & & \\ \hline _Pseudochlorella sp._ & Chl & 1 & 1 & & 1 & 1 & 1 \\ \hline _Stichococcus bacillaris_ & Chl & 1 & & 1 & & 1 \\ \hline _Stichococcus mirabilis_ & Chl & 1 & 1 & & 1 & \\ \hline _Achnantidium cf._ & Ba & & 1 & & & \\ \hline _Chlorella vulgaris_ & Chl & & & & 1 & \\ \hline _Chroococcus turgidus_ & Cy & & & 1 & 1 & 1 \\ \hline _Nostoc punctiforme_ & Cy & & 1 & & & \\ \hline _Oscillatoria tennis_ & Cy & & & & 1 & \\ \hline _Phormidium favosum_ & Cy & 1 & & & & \\ \hline \hline \end{tabular} Ch: Chlorophyta; Ba: Bacillarioophyta; Cy: Cyanophyta.  
\end{table} 
Table 1: Species composition of the phototrophic communities on the SMV, BAR, and ROC churches, expressed as relative frequencies (%) of the total number of cells observed. Figure 2: Species/taxa identified in the different samples observed on the surface of the north- and west-facing walls of the SMV, ROC and BAR churches. Chlorophyta or green algae (**A–N**): (**A,B**) _Tentepolhi_ cf.