Structural diversity of photoautotrophic populations within the UNESCO site ‘Old Cathedral of Coimbra’ (Portugal), using a combined approach

Bacterial and Archaeal Structural Diversity in Several Biodeterioration Patterns on the Limestone Walls of the Old Cathedral of Coimbra

“…With time, due to temperature and humidity fluctuations, these salts react with atmospheric polluters i.e., SOx (sulfur oxides), NOx (nitrogen oxides), and COx (carbon oxides) and precipitate over the exposed surfaces (mainly in the form of gypsum), and this crystallization process, eventually, leads to material disruption and loss [ 27 , 28 , 29 ]. In the studied area, there was visible distinct biofilms development in the different sampled spots (images available in Supplementary Materials Figure S1 ), which are differences that could be related to sunlight exposure and water availability as well as other biotic and abiotic factors [ 7 , 13 , 30 ]. Nevertheless, our results support the assumption that water is most likely one of the main factors shaping the microbiome composition and thus the biofilm development, since in wetter spots (where water is available all year), the presence of more developed biofilms was observed, while less humid spots were characterized by the occurrence of shallower and not so developed biofilms.…”

“…As reported by Soares and colleagues [ 13 ], the development of photosynthetic organisms in these sites can lead to water retention and increased carbon availability in biofilms. This fact provides the support for other microorganisms to follow, such as fungi, bacteria, and archaea.…”

“…A good example is the Old Cathedral of Coimbra (“Sé Velha de Coimbra”) (40°12′32″ N, 8°25′38″ W), a 12th Century Romanesque church, and one of the most iconic and frequently visited monuments in the city. The church was built using mostly yellow dolomitic limestone (i.e., carbonate rock principally composed of calcium magnesium carbonate) from nearby quarries [ 9 , 11 ], and its single-floored cloister contains five semi-open chapels (in the north gallery, chapel of the altarpiece “Natal do Senhor”; in the east gallery, chapels of “São Miguel”, “Santa Cecília”, and “Santa Maria”; and in the south gallery, the chapel of “São Nicolau/Santa Catarina”), deeply affected by biodeterioration phenomena [ 12 , 13 ].…”

“…This fact provides the support for other microorganisms to follow, such as fungi, bacteria, and archaea. The diversity of photosynthetic and fungal organisms in this site was already determined [ 12 , 13 ], and their role in the biodeterioration of the limestone walls was discussed. Although bacteria and archaea are known to also contribute to stone biodeterioration through acidolysis, the removal of cations, and the promotion of mineralization development [ 7 , 18 ], their diversity in these sites remains pending a deep characterization.…”

Epilithic Microalgae Isolated from Biofilm on Borobudur Temple Stone

“…Also, stone inoculation can occur due to increased infiltration of groundwater and windblown dendrites. According to Soares et al (2019), the Chlorophyta division is a cosmopolitan type that is easy to breed and adapt. They often occur in stone monuments and building stone walls, which are anthropogenic surfaces.…”