# Role of Exposure on the Microbial Consortium on Historical Rural Granite Buildings
## 3 Results and Discussion
### Next Generation Sequencing
The other classes of Proteobacteria (Beta and Deltaproteobacteria) were present in much smaller proportions. Species of the order Burkholderiales were found on the N-facing wall of the BAR church and on the W-facing wall of the ROC church, where the genus _Massilia_ appeared; members of the order Myxococcus were mainly distributed on the N-facing walls of the churches, along with members of the genus _Labilitrix_. The most abundant classes within the phylum Bacteroides were Sphingobacteria, Cytophagia and Flavobacteria. Some widely distributed species, such as _Arcticbacter salbardensis_, which belongs to the order Sphingobacterialies, were present on the N-facing walls of all the churches (SMV, BAR and ROC: 5, 5.6, 2.4% respectively) as well as on the west-facing wall of the ROC church (9%). Other species within the same order, e.g., _Pedobacter tournemiensis_, were very abundant, but only on the W-facing wall of the ROC church (11%). Within the order Cytophagales, different species of the genus _Spirosoma_ were found on both the N-and W-facing walls of the BAR church, specifically _Spirosoma rigui_ (3.5%), and _Siccationidurans ginsengli_ was only found on the W-facing wall of the ROC church (5.6%). Finally, within the order Flavobacterialies, the species _Pricia antarctica_ and _Flavimarina paclifica_ (6.5 and 8.8%) occurred on the N-facing wall of the SMV church. The most common orders in the phylum Acidobacteria were Solipabacterales and Acidobacterialies. The former is mainly represented by one species, _Paludibaccum fermentans_, which was only found on the N-facing walls of BAR and ROC churches (1.3 and 3%). In the case of the order Acidobacterialies, the species _Granulicella acidophila_ was found on the N- and W-facing walls of the ROC church (11.7 and 11.6%), as well as on the N-facing wall of SMV (14%). This species is clearly acidophilic and is known to produce large amounts of EPS and carotenoids [60] which can be important in terms of biodeterioration. _Silvibacterium boemicum_ was found on both the N- and W-facing walls (8.3 and 1.5%) of the ROC church. Other species of the order, such as _Edaphobacter modestus_, _Granulicella malensis_ and _Terribolous aquaticus_, were found in smaller percentages in the N-facing wall of the church of BAR, while _Bryocella elongata_, _Terriglobus aquaticus_ and _Terriglobus roseus_ were found on the W-facing wall of the ROC church. Regarding the phylum Plinctomycetes, only species belonging to two classes were found: Plinctomyctia and Phycisphaerae. The first class has three different widely distributed species: _Aquisphaera giovannonii_ was found at all sites at a percentage abundance of between 1 and 9%, except on the W-facing wall of the ROC church; _Paludisphaera borealis_ was found on the N-facing walls of the SMV and ROC churches and on the W-facing wall of the ROC church (between 1 and 3%); and _Singulisphaera rosea_, found on both the N- and W-facing walls of the BAR and ROC churches. The class Phycisphaerae was represented by a single species, _Tepidisphaera mucosa_, which occurred on the BAR church, with a percentage abundance of 2.5%, on both N- and W-facing walls. The phylum Actinobacteria was mainly found on W-facing walls. The order Rubbroacterales was represented by species such as _Rubbroacter radiotolerans_ on the W-facing wall of the SMV and BAR churches (5.7 and 2%). In addition, other species of the Rubbroacter genus were abundant on the SMV and ROC churches (between 1 and 9%). This genus has been widely linked to the biodeterioration of monuments and is known to contribute to the so-called rosy discoloration [61]. The pigment production is related to the high desiccation tolerance of this genus, which confers a selective advantage over other organisms [40]. Other orders such as Kineosporiales and Micrococcales were also abundant on the walls of the SMV church.