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9 páginas.- 5 figuras.- 3 tablas.- referencias.-. The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fmicb. 2022.982933/full#supplementary-material .- This article is part of the Research Topic Microbial Roles in Caves, The present study reports a sudden fungal outbreak that occurred in the corridor near the entrance of the Catacombs of SS. Marcellino and Pietro in Rome (Italy) observed after 1 year of a restoration treatment that interested the walls of the entrance of the Catacombs and some artifacts placed in situ. The colonization was observed on the vault at the entrance and in correspondence with the restored marble pieces displayed on the left side of the corridor. No growth was observed on the right side where similarly treated marble slabs were placed. Samples taken in correspondence with fungal biofilm were analyzed through the combined use of microscopical, cultural, and molecular tools and showed that the vault and the left side of the corridor entrance were colonized by a complex fungal biofilm consisting mainly of Coniophora sp. and other genera, such as Hypomyces, Purpureocillium, Acremonium, Penicillium, and Alternaria, many of which are well known as responsible of biodeterioration of stone surfaces. Regarding the brown-rot basidiomycete Coniophora, it was able to form very large colonies on the substrata with a diameter of up to 57 cm. Although the direct observation under a light microscope evidenced the presence of abundant brown fungal conidia, several attempts to cultivate the microorganism failed, therefore only through DNA sequencing analyses, it was possible to identify and characterize this fungus. There is very little literature on the genus Coniophora which is reported as one of the causes of wet-rot decay of wood in buildings. A connection with calcium-containing materials such as bricks and mortars was demonstrated, but no data were available about the possible role of this species in the biodeterioration of stones. This study features the first finding of a strain related to the basidiomycetous genus of Coniophora in the order Boletales in association with evident phenomena of biodeterioration., This project was supported thanks to the special funds provided by the University of Messina (approved on 21 February 2022 by the Academic Senatus) (Italy), the Spanish Ministry of Science and Innovation, and project PID2020-114978GB-I00 and project CIACCO DTC TE1 - FASE II - PROGETTI RSI8.

12 paginas.- 5 figuras.- referencias.- The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fmicb.2022.869661/full#supplementary-material, Castañar Cave is a clear example of an oligotrophic ecosystem with high hygrothermal stability both seasonal and interannual and the particularity of registering extraordinary levels of environmental radiation. These environmental conditions make the cave an ideal laboratory to evaluate both the responses of the subterranean environment to sudden changes in the matter and energy fluxes with the exterior and also any impact derived from its use as a tourist resource under a very restrictive access regime. In 2008, a fungal outbreak provoked by a vomit contaminated the sediments which were removed and subsequently treated with hydrogen peroxide. Fungal surveys were carried out in 2008 and 2009. The visits were resumed in 2014. Here, 12 years after the outbreak, we present an exhaustive study on the cave sediments in order to know the distribution of the different fungal taxa, as well as the prevalence and spatio-temporal evolution of the fungi caused by the vomit over the years under the conditions of relative isolation and high radiation that characterize this cave., This research was supported by the Spanish Ministry of Science and Innovation through project PID2019-110603RB-I00 and the collaboration of PID2020-114978GB-I00 project, MCIN/AEI/FEDER, UE/10.13039/501100011033.