Gypsum Cave Biofilm Communities are Strongly Influenced by Bat- And Arthropod-Related Fungi.

The Gypsum Karst of Sorbas, Almeria, southeast Spain, includes a few caves whose entrances are open and allow the entry and roosting of numerous bats. Caves are characterized by their diversity of gypsum speleothems, such as stalactites, coralloids, gypsum crusts, etc. Colored biofilms can be observed on the walls of most caves, among which the Covadura and C3 caves were studied. The objective was to determine the influence that bat mycobiomes may have on the fungal communities of biofilms. The results indicate that the fungi retrieved from white and yellow biofilms in Covadura Cave (Ascomycota, Mortierellomycota, Basidiomycota) showed a wide diversity, depending on their location, and were highly influenced by the bat population, the guano and the arthropods that thrive in the guano, while C3 Cave was more strongly influenced by soil- and arthropod-related fungi (Ascomycota, Mortierellomycota), due to the absence of roosting bats.

A Second Fungal Outbreak in Castañar Cave, Spain, Discloses the Fragility of Subsurface Ecosystems.

Castañar is a cave with strict visitor control measures since it was open to public visits in 2003. However, in recent years, the cave suffered two fungal outbreaks, the first in 2008 and controlled by cleaning the contaminated sediments and subsequent closure of the cave until 2014. The cave was reopened but limited to a maximum of 450 visitors/year. Despite these restrictions on visit, the cave experienced a second outbreak in 2021, originating from the installation of a steel grating walkway, aiming at protecting the ground sediments from the visitors' footsteps. Here, we conducted an analysis using Next-Generation Sequencing and culture-dependent techniques to investigate the fungal communities related to the second outbreak and compare with those present before the cave suffered the outbreak. The results show that the most abundant fungi involved in the 2021 outbreak were already detected in 2020, and even in 2008 and 2009, although the main species that originating both outbreaks were different, likely due to the different carbon sources introduced into the cave.

Microclimate, airborne particles, and microbiological monitoring protocol for conservation of rock-art caves: The case of the world-heritage site La Garma cave (Spain).

Cave heritage is often threatened by tourism or even scientific activities, which can lead to irreversible deterioration. We present a preventive conservation monitoring protocol to protect caves with rock art, focusing on La Garma Cave (Spain), a World Heritage Site with valuable archaeological materials and Palaeolithic paintings. This study assessed the suitability of the cave for tourist use through continuous microclimate and airborne particles monitoring, biofilm analysis, aerobiological monitoring and experimental visits. Our findings indicate several factors that make it inadvisable to adapt the cave for tourist use. Human presence and transit within the cave cause cumulative effects on the temperature of environmentally very stable and fragile sectors and significant resuspension of particles from the cave sediments. These environmental perturbations represent severe impacts as they affect the natural aerodynamic control of airborne particles and determine bacterial dispersal throughout the cave. This monitoring protocol provides part of the evidence to design strategies for sustainable cave management.

Paracoccus onubensis sp. nov., a novel alphaproteobacterium isolated from the wall of a show cave.

A novel facultatively anaerobic, non-motile, Gram-stain-negative, non-endospore-forming alphaproteobacterium, strain 1011MAR3C25T, was isolated from a white biofilm colonizing the walls of the Andalusian show cave Gruta de las Maravillas (Huelva, Spain). Strain 1011MAR3C25T grew at 8-42 °C (optimum, 20-30 °C), at pH 5.0-9.0 (optimum, pH 5.0-6.0) and in the presence of 0-12 % (w/v) NaCl (optimum 3-5 %). Cells were catalase- and oxidase-positive. The strain grew heterotrophically with various carbon sources and chemoautotrophically with thiosulfate under aerobic conditions. Results of phylogenetic analysis showed that strain 1011MAR3C25T was related to Paracoccus saliphilus DSM 18447T and Paracoccus alkanivorans LMG 30882T (97.90 % and 97.32 % 16S rRNA sequence identity values, respectively). The major respiratory quinone was ubiquinone Q-10 and the predominant fatty acid was C18 : 1 ω7c. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylcholine, phosphatidylglycerol, an unidentified aminolipid, an unidentified glycolipid and an unidentified polar lipid. The DNA G+C content was 60.3 mol%. Based on a polyphasic taxonomic study it is proposed that strain 1011MAR3C25T (=CECT 9092T=LMG 29414T) represents a novel species of the genus Paracoccus, for which the name Paracoccus onubensis sp. nov. is proposed.

Environment-driven control of fungi in subterranean ecosystems: the case of La Garma Cave (northern Spain).

Airborne microorganisms can cause important conservation problems in caves with Paleolithic art and therefore the knowledge of cave aerodynamic is essential. La Garma Cave (Cantabria, Spain), an exceptional archaeological site with several levels of galleries interconnected and two entrances, presents a complex atmospheric dynamics. An approach including aerobiological sampling together with microclimate monitoring was applied to assess the factors controlling the origin of airborne fungi. Here we show that winter ventilation is critical for the increasing of Basidiomycota spores in the cave air and the highest concentrations were found in the most ventilated areas. On the contrary, Ascomycota spores prevailed in absence of ventilation. Besides, most Ascomycota were linked to insects and bats that visit or inhabit the cave. The combination of aerobiological and microclimate data constitutes a good approach to evaluate the influence of external climatic conditions and design the most suitable strategies for the conservation of cultural heritage in the cave environment.

Microbial Community Characterizing Vermiculations from Karst Caves and Its Role in Their Formation.

The microbiota associated with vermiculations from karst caves is largely unknown. Vermiculations are enigmatic deposits forming worm-like patterns on cave walls all over the world. They represent a precious focus for geomicrobiological studies aimed at exploring both the microbial life of these ecosystems and the vermiculation genesis. This study comprises the first approach on the microbial communities thriving in Pertosa-Auletta Cave (southern Italy) vermiculations by next-generation sequencing. The most abundant phylum in vermiculations was Proteobacteria, followed by Acidobacteria > Actinobacteria > Nitrospirae > Firmicutes > Planctomycetes > Chloroflexi > Gemmatimonadetes > Bacteroidetes > Latescibacteria. Numerous less-represented taxonomic groups (< 1%), as well as unclassified ones, were also detected. From an ecological point of view, all the groups co-participate in the biogeochemical cycles in these underground environments, mediating oxidation-reduction reactions, promoting host rock dissolution and secondary mineral precipitation, and enriching the matrix in organic matter. Confocal laser scanning microscopy and field emission scanning electron microscopy brought evidence of a strong interaction between the biotic community and the abiotic matrix, supporting the role of microbial communities in the formation process of vermiculations.

Paracoccus cavernae sp. nov., isolated from a show cave.

A Gram-stain-negative, aerobic, non-motile, non-spore-forming bacterium, strain 0511ARD5E5T, was isolated from an air sample collected in Ardales Cave (Malaga, Spain). Strain 0511ARD5E5T grew at 4-37 °C and in the presence of 0-4 % (w/v) NaCl [optimally at 25 °C and with 1 % (w/v) NaCl]. Cells were catalase- and oxidase-positive. The major respiratory quinone was ubiquinone-10. The predominant fatty acids were C18:1ω7c and C16:0. The DNA G+C content was 63.2 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 0511ARD5E5T was a member of the genus Paracoccus and was related most closely to Paracoccus aminophilus DSM 8538T and Paracoccus marinus CIP 108500T (96.93 and 96.92 % similarity, respectively). Strain 0511ARD5E5T exhibited DNA-DNA relatedness of 47 % to P. aminophilus DSM 8538T and 31 % to P. marinus CIP 108500T. Chemotaxonomic, phenotypic and phylogenetic analyses indicated that strain 0511ARD5E5T represents a novel species of the genus Paracoccus, for which the name Paracoccus cavernae sp. nov. is proposed. The type strain is 0511ARD5E5T (=LMG 27962T=CECT 8482T).

Microbiological exploration of the Cueva del Viento lava tube system in Tenerife, Canary Islands.

Cueva del Viento, located in the Canary Islands, Spain, is the Earth's sixth-longest lava tube, spanning 18,500 m, and was formed approximately 27,000 years ago. This complex volcanic cave system is characterized by a unique geomorphology, featuring an intricate network of galleries. Despite its geological significance, the geomicrobiology of Cueva del Viento remains largely unexplored. This study employed a combination of culture-dependent techniques and metabarcoding data analysis to gain a comprehensive understanding of the cave's microbial diversity. The 16S rRNA gene metabarcoding approach revealed that the coloured microbial mats (yellow, red and white) coating the cave walls are dominated by the phyla Actinomycetota, Pseudomonadota and Acidobacteriota. Of particular interest is the high relative abundance of the genus Crossiella, which is involved in urease-mediated biomineralization processes, along with the presence of genera associated with nitrogen cycling, such as Nitrospira. Culture-dependent techniques provided insights into the morphological characteristics of the isolated species and their potential metabolic activities, particularly for the strains Streptomyces spp., Paenarthrobacter sp. and Pseudomonas spp. Our findings underscore the potential of Cueva del Viento as an ideal environment for studying microbial diversity and for the isolation and characterization of novel bacterial species of biotechnological interest.

Adaptive response of prokaryotic communities to extreme pollution flooding in a Paleolithic rock art cave (Pindal Cave, northern Spain).

A flood event affecting Pindal Cave, a UNESCO World Heritage site, introduced a substantial amount of external sediments and waste into the cave. This event led to the burial of preexisting sediments, altering the biogeochemical characteristics of the cave ecosystem by introducing heightened levels of organic matter, nitrogen compounds, phosphorus, and heavy metals. The sediments included particulate matter and waste from a cattle farm located within the water catchment area of the cavity, along with diverse microorganisms, reshaping the cave microbial community. This study addresses the ongoing influence of a cattle farm on the cave ecosystem and aims to understand the adaptive responses of the underground microbial community to the sudden influx of waste allochthonous material. Here, we show that the flood event had an immediate and profound effect on the cave microbial community, marked by a significant increase in methanogenic archaea, denitrifying bacteria, and other microorganisms commonly associated with mammalian intestinal tracts. Furthermore, our findings reveal that one year after the flood, microorganisms related to the flood decreased, while the increase in inorganic forms of ammonium and nitrate suggests potential nitrification, aligning with increased abundances of corresponding functional genes involved in nitrogen cycling. The results reveal that the impact of pollution was neither recent nor isolated, and it was decisive in stopping livestock activity near the cave. The influence of the cattle farm has persisted since its establishment over the impluvium area, and this influence endures even a year after the flood. Our study emphasizes the dynamic interplay between natural events, anthropogenic activities, and microbial communities, offering insights into the resilience of cave ecosystems. Understanding microbial adaptation in response to environmental disturbances, as demonstrated in this cave ecosystem, has implications for broader ecological studies and underscores the importance of considering temporal dynamics in conservation efforts.

Sphingopyxis italica sp. nov., isolated from Roman catacombs.

A Gram-stain-negative, aerobic, motile, rod-shaped bacterium, strain SC13E-S71(T), was isolated from tuff, volcanic rock, where the Roman catacombs of Saint Callixtus in Rome, Italy, was excavated. Analysis of 16S rRNA gene sequences revealed that strain SC13E-S71(T) belongs to the genus Sphingopyxis, and that it shows the greatest sequence similarity with Sphingopyxis chilensis DSM 14889(T) (98.72 %), Sphingopyxis taejonensis DSM 15583(T) (98.65 %), Sphingopyxis ginsengisoli LMG 23390(T) (98.16 %), Sphingopyxis panaciterrae KCTC 12580(T) (98.09 %), Sphingopyxis alaskensis DSM 13593(T) (98.09 %), Sphingopyxis witflariensis DSM 14551(T) (98.09 %), Sphingopyxis bauzanensis DSM 22271(T) (98.02 %), Sphingopyxis granuli KCTC 12209(T) (97.73 %), Sphingopyxis macrogoltabida KACC 10927(T) (97.49 %), Sphingopyxis ummariensis DSM 24316(T) (97.37 %) and Sphingopyxis panaciterrulae KCTC 22112(T) (97.09 %). The predominant fatty acids were C18 : 1ω7c, summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1ω7c), C14 : 0 2-OH and C16 : 0. The predominant menaquinone was MK-10. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and sphingoglycolipid. These chemotaxonomic data are common to members of the genus Sphingopyxis. However, a polyphasic approach using physiological tests, DNA base ratios, DNA-DNA hybridization and 16S rRNA gene sequence comparisons showed that the isolate SC13E-S71(T) belongs to a novel species within the genus Sphingopyxis, for which the name Sphingopyxis italica sp. nov. is proposed. The type strain is SC13E-S71(T) ( = DSM 25229(T) = CECT 8016(T)).

Nocardioides albertanoniae sp. nov., isolated from Roman catacombs.

A Gram-reaction-positive, aerobic, non-spore-forming, rod- or coccoid-shaped, strain, CD40127(T), was isolated from a green biofilm covering the wall of the Domitilla Catacombs in Rome, Italy. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CD40127(T) belongs to the genus Nocardioides, closely related to Nocardioides luteus DSM 43366(T) and Nocardioides albus DSM 43109(T) with 98.86 % and 98.01 % similarity values, respectively. Strain CD40127(T) exhibited 16S rRNA gene sequence similarity values below 96.29 % with the rest of the species of the genus Nocardioides. The G+C content of the genomic DNA was 69.7 mol%. The predominant fatty acid was iso-C16 : 0 and the major menaquinone was MK-8(H4) in accordance with the phenotypes of other species of the genus Nocardioides. A polyphasic approach using physiological tests, fatty acid profiles, DNA base ratios and DNA-DNA hybridization showed that isolate CD40127(T) represents a novel species within the genus Nocardioides, for which the name Nocardioides albertanoniae is proposed. The type strain is CD40127(T) ( = DSM 25218(T) = CECT 8014(T)).

Prokaryotic communities inhabiting a high-radon subterranean ecosystem (Castañar Cave, Spain): Environmental and substrate-driven controls.

Castañar Cave (Caceres, Spain) is a unique show cave known for its high natural radiation levels. This study presents a comprehensive analysis of its prokaryotic diversity, specifically focusing on investigating the influence of environmental conditions and substrate characteristics on the prokaryotic community structure in the cave sediments. Additionally, the research aims to evaluate the potential impact of human activities on the cave ecosystem. The identification of distinct bioclimatic zones within the cave was made possible through a combination of environmental and microbial monitoring (ATP assays). The results reveal sediment texture as a significant factor, notably affecting the structure, diversity, and phylogenetic variability of the microbial community, including both Bacteria and Archaea. The proportion of clay minerals in sediments plays a crucial role in regulating moisture levels and nutrient availability. These substrate properties collectively exert a significant selective pressure on the structure of prokaryotic communities within cave sediments. The molecular approach shows that heterotrophic bacteria, including those with chitinolytic enzymes, primarily inhabit the cave. Furthermore, chemoautotrophic nitrifiers such as the archaea Nitrososphaeria and the genus Nitrospira, as well as methanotrophic bacteria from the phyla Methylomirabilota, Pseudomonadota, and Verrucomicrobiota, are also present. Remarkably, despite being a show cave, the cave microbiota displays minimal impacts from human activities and the surface ecosystem. Prokaryotic populations exhibit stability in the innermost areas, while the tourist trail area experiences slightly higher biomass increases due to visitor traffic. This suggests that conservation efforts have successfully limited the entry of external nutrients into the innermost cave areas. Additionally, the results suggest that integrating biomarkers like ATP into environmental monitoring can significantly enhance the methods used to study the negative impacts of tourism on cave ecosystems.

New insights into the structure, microbial diversity and ecology of yellow biofilms in a Paleolithic rock art cave (Pindal Cave, Asturias, Spain).

In the absence of sunlight, caves harbor a great diversity of microbial colonies to extensive biofilms with different sizes and colors visible to the naked eye. One of the most widespread and visible types of biofilm are those with yellow hues that can constitute a serious problem for the conservation of cultural heritage in many caves, such as Pindal Cave (Asturias, Spain). This cave, declared a World Heritage Site by UNESCO for its Paleolithic parietal art, shows a high degree of development of yellow biofilms that represents a real threat to the conservation of painted and engraved figures. This study aims to: 1) identify the microbial structures and the most characteristic taxa composing the yellow biofilms, 2) seek the linked microbiome reservoir primarily contributing to their growth; 3) seed light on the driving vectors that contribute to their formation and determine the subsequent proliferation and spatial distribution. To achieve this goal, we used amplicon-based massive sequencing, in combination with other techniques such as microscopy, in situ hybridization and environmental monitoring, to compare the microbial communities of yellow biofilms with those of drip waters, cave sediments and exterior soil. The results revealed microbial structures related to the phylum Actinomycetota and the most characteristic bacteria in yellow biofilms, represented by the genera wb1-P19, Crossiella, Nitrospira, and Arenimonas. Our findings suggest that sediments serve as potential reservoirs and colonization sites for these bacteria that can develop into biofilms under favorable environmental and substrate conditions, with a particular affinity for speleothems and rugged-surfaced rocks found in condensation-prone areas. This study presents an exhaustive study of microbial communities of yellow biofilms in a cave, which could be used as a procedure for the identification of similar biofilms in other caves and to design effective conservation strategies in caves with valuable cultural heritage.

Uncovering the origin of the black stains in Lascaux Cave in France.

Lascaux Cave in France was discovered in 1940. Since being opened to visitors the cave has suffered three major microbial outbreaks. The current problem is the fast dissemination of black stains which are threatening the Palaeolithic paintings. Previous data pointed to the involvement of new fungal species in the formation of black stains on the rock walls and ceiling. However, it appears that there could be other reasons for the formation of different and extensive black stains coating the surface of the clayey sediments. Our analyses reveal that black stains on clayey sediments are mainly produced by Acremonium nepalense, a manganese oxide-depositing fungus, widely distributed in the cave. Thus, in Lascaux Cave, the black stains have a dual origin: on limestone rocks they are mainly produced by the accumulation of fungal melanins, and on clayey sediments by the biogenic deposition of black manganese oxides.

Aspergillus baeticus sp. nov. and Aspergillus thesauricus sp. nov., two species in section Usti from Spanish caves.

Two novel species of Aspergillus that are clearly distinct from all known species in section Usti were revealed during a study of microfungal communities in Spanish caves. The novel species identified in this study and additional species of Aspergillus section Usti are associated with places and substrates related to human activities in caves. Novel species are described using data from four loci (ITS, benA, caM and rpb2), morphology and basic chemical and physiological analyses. Members of the species Aspergillus thesauricus sp. nov. were isolated from various substrates, including decaying organic matter, cave air and cave sediment of the Cueva del Tesoro Cave (the Treasure cave); the species is represented by twelve isolates and is most closely related to the recently described Aspergillus germanicus. Members of the species Aspergillus baeticus sp. nov. were isolated from cave sediment in the Gruta de las Maravillas Cave (the Grotto of the Marvels); the species is represented by two isolates. An additional isolate was found in the Cueva del Tesoro Cave and in the Demänovská Peace Cave (Slovakia), suggesting a potentially wide distribution of this micro-organism. The species is related to Aspergillus ustus and Aspergillus pseudoustus. Both species were unable to grow at 37 °C, and a weakly positive, light greenish yellow Ehrlich reaction was observed in A. thesauricus. Unique morphological features alone are sufficient to distinguish both species from related taxa.

Use of biocides for the control of fungal outbreaks in subterranean environments: the case of the Lascaux Cave in France.

The Lascaux Cave in France suffered an outbreak of the fungus Fusarium solani in 2001. Biocides were applied for three years to control this outbreak. Four months after the initial biocide application, a new outbreak appeared in the form of black stains that progressively invaded the cave. The black stains on the ceiling and passage banks were so evident by 2007 that they became one of the cave's major problems. Therefore, biocides were used again in 2008. The present study investigated the fungal communities associated with the black stains and the effectiveness of the biocides applied, by using cloning, denaturing gradient gel electrophoresis, and culture-dependent methods. A novel species, Ochroconis lascauxensis, was the most abundant fungus in samples collected between 2007 and 2008, and the biocides applied were not effective in eliminating this fungus; on the contrary, they appeared to increase the fungal diversity. The fungal communities represented in the samples collected in 2010 were quite different from those collected in 2008 and 2009: the major OTUs corresponded to black yeasts belonging to the Herpotrichiellaceae family. The origin and evolution of these microorganisms are probably linked to the intensive biocide treatments and to the anthropogenic changes introduced by cave management.

Microbiological and environmental issues in show caves.

Cultural tourism expanded in the last half of the twentieth century, and the interest of visitors has come to include caves containing archaeological remains. Some show caves attracted mass tourism, and economical interests prevailed over conservation, which led to a deterioration of the subterranean environment and the rock art. The presence and the role of microorganisms in caves is a topic that is often ignored in cave management. Knowledge of the colonisation patterns, the dispersion mechanisms, and the effect on human health and, when present, over rock art paintings of these microorganisms is of the utmost importance. In this review the most recent advances in the study of microorganisms in caves are presented, together with the environmental implications of the findings.

Streptomyces benahoarensis sp. nov. Isolated From a Lava Tube of La Palma, Canary Islands, Spain.

Two Streptomyces strains, labeled as MZ03-37T and MZ03-48, were isolated from two different samples, a mucolite-type speleothem and a microbial mat on the walls of a lava tube from La Palma Island (Canary Islands). Phylogenetic analysis based on concatenated sequences of six housekeeping genes indicated that both strains belonged to the same species. The closest relatives for both strains were Streptomyces palmae CMU-AB204T (98.71%), Streptomyces catenulae NRRL B-2342T (98.35%), and Streptomyces ramulosus NRRL B-2714T (98.35%). Multi-locus sequence analysis (MLSA), based on five house-keeping gene alleles (i.e., atpD, gyrB, recA, rpoB, and trpB), indicated that both isolated strains were closely related to S. catenulae NRRL B-2342T. Whole-genome average nucleotide identity (ANI) scores of both strains were in the threshold value for species delineation with the closest species. Both strains presented a G+C content of 72.1 mol%. MZ03-37T was light brown in substrate and white in aerial mycelium, whereas MZ03-48 developed a black aerial and substrate mycelium. No pigment diffusion was observed in both strains. They grew at 10°C-37°C (optimum 28°C-32°C) and in the presence of up to 15% (w/v) NaCl. MZ03-37T grew at pH 5-10 (optimal 6-9), whereas MZ03-48 grew at pH 4-11 (optimal 5-10). LL-Diaminopimelic acid was the main diamino acid identified. The predominant fatty acids in both strains were iso-C16:0, anteiso-C15:0, C16:0, and iso-C14:0. The major isoprenoid quinones were MK-9(H6) and MK-9(H8), and the main polar lipids were aminolipid, phospholipid, and phosphoglycolipid. In silico analyses for functional annotation predicted the presence of gene clusters involved in resistome mechanisms and in the synthesis of described antimicrobials such as linocin-M18 and curamycin, as well as different genes likely involved in mechanisms for active compound synthesis, both already described and not discovered so far. On the basis of their phylogenetic relatedness and their phenotypic and genotypic features, the strains MZ03-37T and MZ03-48 represented a novel species within the genus Streptomyces, for which the name Streptomyces benahoarensis sp. nov. is proposed. The type strain is MZ03-37T (= CECT 9805 = DSMZ 8002); and MZ03-48 (= CECT 9806 = DSMZ 8011) is a reference strain.

Fungal outbreak in the Catacombs of SS. Marcellino and Pietro Rome (Italy): From diagnosis to an emergency treatment.

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.

Diversity of Microfungi in a High Radon Cave Ecosystem.

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.