Rock-Building Fungi

Fungi are a major component of the biota in soils and mineral substrates occurring over a wide range of geographical and climatic zones, and are often dominant when compared to other organisms, including bacteria. Due to their filamentous growth habit and ability to excrete organic acids, protons and other metabolites, fungi are perfectly suited as biological weathering agents of natural rocks, minerals, including those used in building materials. Small tunnels discovered inside weatherable minerals in soil were hypothesized to be formed by mineral-solubilizing activities of ectomycorrhizal fungi. Using scanning electron microscopy techniques to visualise in situ fungal weathering of rock, patina formation and secondary mineral precipitation we provide an additional explanation for the occurrence of fungal tunnels inside minerals using carbonates and oxalates as examples. Our findings highlight fungal potential for mineral transformations and their ability to precipitate secondary mycogenic minerals within rock substrata.