The “University of Coimbra-Alta and Sofia” area was awarded the UNESCO World Heritage Site distinction in 2013. The Old Cathedral of Coimbra, a 12th-century limestone monument located in this area, has been significantly impacted during the last 800 years by physical, chemical, and biological processes. This led to the significant deterioration of some of its structures and carvings, with loss of aesthetical, cultural, and historical values. For this work, deteriorated spots of the walls of three semi-open chapels from the cloister of the Cathedral were sampled to ascertain their bacterial and archaeal structural diversity. Based on Next-Generation Sequencing (NGS) result analysis, we report the presence of microbial populations that are well adapted to an ecosystem with harsh conditions and that can establish a diverse biofilm in most cases. While it was possible to determine dominant phylogenetic groups in Archaea and Bacteria domains, there was no clear connection between specific core microbiomes and the different deterioration patterns analyzed. The distribution of these archaeal and bacterial communities within the analyzed biodeterioration spots suggests they are more influenced by abiotic factors (i.e., water availability, salinity, etc.), although they influence (and are influenced by) the algal and fungal population composition in this ecosystem. This work provides valuable information that can assist in establishing future guidelines for the preservation and conservation of this kind of historic stone monuments.

In a study that aimed to fingerprint the phototrophic community of the biodeteriorated walls of the Old Cathedral of Coimbra (UNESCO World Heritage Site), an unknown Nostoc/Komarekiella-like cyanobacterium was isolated. We employed a polyphasic approach based on morphological, ecological and phylogenetic analyses of the partial 16S and the whole 16S-23S ITS rRNA regions to characterize this organism. Our strains shared 16S rRNA gene sequence similarity of 99–100% with GenBank-assigned ‘Nostoc sp.’ sequences, and 98% similarity with the genera Goleter, Roholtiella, Aulosira and Komarekiella. Despite being morphologically similar to Komarekiella, phylogenetic analyses placed our strains in a separated genus-level clade, distant from Nostoc sensu stricto and with Komarekiella as the closest taxon. Considering all molecular, phylogenetic and ecological data, we here propose Parakomarekiella sesnandensis F.Soares, V.Ramos & A.Portugal, gen. et sp. nov.

Cyanobacteria are photoautotrophic microorganisms able to colonize historic stone monuments, causing severe aesthetic, physical and chemical alterations to the substrate. In a study that aimed to fingerprint the phototrophic community of the biodeteriorated walls of the Old Cathedral of Coimbra (UNESCO World Heritage Site), an unknown Myxacorys-like cyanobacterium was isolated. In this paper, we employed a polyphasic approach based on morphological, ecological and phylogenetic analyses of the partial 16S and the whole 16S-23S ITS rRNA regions. The resulting analyses allowed us to propose the description of a new species, Myxacorys almedinensis sp. nov. within the genus Myxacorys.

Stone monuments and relics are prone to biodeterioration processes prompted by microbial proliferation and activity. Among the distinct microbes capable of stone colonization, fungi are known to strongly contribute to stone biodeterioration. During the ongoing efforts aiming to study fungi thriving in dolomitic limestone walls of the Coimbra’s hypogean Roman cryptoporticus (Portugal), two unknown Bionectriaceae isolates were retrieved. The aim of this work was to depict the molecular and phenotypic characteristics of these microorganisms. The phylogenetic analyses revealed that the studied strains could not be assigned to any of the currently known Bionectriaceae genera. Moreover, the isolates exhibited distinctive and peculiar characteristics, such as the packing of conidia by surrounding hyphal segments and the formation of rope-like microsclerotia with a textura globose. Taking into account all the data obtained, a novel genus and species, Circumfusicillium cavernae gen. et sp. nov. in Bionectriaceae (Hypocreales), is proposed here.