Fungal diversity and distribution across distinct biodeterioration phenomena in limestone walls of the old cathedral of Coimbra, UNESCO World Heritage Site

Abstract

Fungi are powerful biodeteriogens and when colonizing stone monuments are often responsible for severe physical, chemical and aesthetical modifications. Recently the old cathedral of Coimbra (Portugal) was awarded the UNESCO World Heritage Site distinction as an integrant part of the “University of Coimbra- Alta and Sofia” area. The limestone walls in this cathedral show clear visual signs of biological colonization and biodeterioration. The aim of this work was to obtain an extensive fingerprint of the biodeteriorating fungal agents in this affected ancient limestone through the application of traditional cultivation and modern Next Generation Sequencing techniques. Due to high diversity of distinctive biodeterioration phenomena affecting this site, a rapport between the identified fungal populations and the different biodeterioration types found was also established and their importance for the monument preservation discussed. The results obtained through the application of this approach, not only allowed a robust characterization of the fungal communities colonizing this monument, but also elucidated that distinct fungal communities are dissimilar according to the type of biodeterioration analyzed. In addition, we verified that both cultivation and metagenomics methodologies should be employed synergistically in limestone biodeterioration studies in order to tackle inherent limitations regarding both techniques.