Linking ornamental stone discolouration to its biocolonisation state

Colour in historic and modern architecture is one of the most important visible characteristics that should be preserved along the times. There are many factors that can induce stone weathering, promoting its discolouration. Among these factors, microorganisms’ action was neglected for many decades, and nowadays there is a lack of association in the relation of stone alteration and biogenic activity. This work comprises an important contribution to understand the microbial role for the weathering of one of the more important Portuguese stones, that is applied in historic monuments and new buildings. Featured by its excellent physico-chemical characteristics, this lithotype is currently with a great international demand, which requires a thorough comprehension of its deterioration mechanism. The natural weathering of this stone was induced through simulation assays and the microbiota thriving were evaluated and characterised using Next Generation Sequencing. The results obtained show that the stone discolouration is greater when both prokaryotic and eukaryotic colonisers are present and the inorganic surface alteration promotes the development of microbiota, creating a cause-effect cycle.