In vitro analyses of fungi and dolomitic limestone interactions: Bioreceptivity and biodeterioration assessment

Dolomitic limestones are carbonate rocks with an inherent high intrinsic bioreceptivity, being especially prone to microbial colonization. Nonetheless, fungal dolomitic limestone bioreceptivity and biodeterioration still remains scarcely characterized. As such, the aims of this work were to: evaluate the biodeteriorative abilities of previously isolated fungi thriving at the Old Cathedral of Coimbra; access fungal limestone bioreceptivity in a laboratory simulated oligotrophic and copiotrophic environment; and to characterize the biodeterioration impacts of these organisms. The obtained results allowed to determine that a significant number of the tested species displayed in vitro biodeteriorative abilities. Inoculation of these species in dolomitic limestone replicas for one year revealed that, with a few exceptions, fungal proliferation was slightly superior in oligotrophic rather than copiotrophic conditions and that, in general, Penicillium chrysogenum, Periconia byssoides and Parengyodontium album displayed the highest average colonization rates. Moreover, most of the tested species produced noticeable alterations in the form of mineral disaggregation, displacement and possible dissolution. The obtained results also allowed to detect calcite mineralization in or near some species hyphae, suggesting that after one-year fungal stone diagenesis and secondary biomineralization was already occurring. This study contributed to further elucidate the nefarious effect resulting from fungal proliferation on dolomitic limestone.