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17 páginas.- 7 figuras.- 4 tablas.- referecias.- The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/feart.2020.586248/full#supplementary-material .- We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)., Morgana Cave is located in Val di Scerscen, Central Italian Alps. The cave opens at an altitude of 2,600 m a.s.l. close to the retreating glacier Vedretto di Scerscen, and its entrance was discovered 30 years ago hidden underneath the glacier. A characteristic of this cave is the occurrence of vermiculation deposits on the walls and ceiling. In general, the composition of the microbial communities in cave vermiculations is relatively unknown and rarely investigated. Here we present the data of a geomicrobiological study of vermiculations from an Alpine cave subjected to extreme climate conditions. The microbial communities were dominated by 13 main phyla of Bacteria, and contained a negligible percentage (, Funding was provided by the Spanish project MINECO CGL2016-75590-P with ERDF funds. The Rotary Club in Sondrio (Italy) also provided funds for sample analysis thanks to C. Mazza, M. Boccardi, and P. Nana, with the Municipality of Lanzada (S. Bardea) and the Istituto Mineralogico Valtellinese (I. Foianini) supporting the cave research project..- We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).

13 págins.-- 9 figuras.-- 3 tablas.-- 24 referencias, The Roman Necropolis of Carmona (Sevilla, Spain) has experienced a severe deterioration since the accidental discovery in 1868 and subsequent archaeological excavations starting in 1882. To this deterioration contributed the location in a soft calcarenite rock quarry, the adverse environmental conditions and the numerous and extensive wrong archaeological and managing interventions along more than a century. The cultural, artistic and religious importance of this Necropolis converts the protection and conservation of this archaeological site in a major issue. This work present the data obtained in a multidisciplinary research were geology, geomorphology, micro-environmental and climatic monitoring, rock petrophysical characterization, description of weathering forms and biological colonization were considered in order to propose corrective measures to minimize deterioration., This research was funded by the Consejería de Cultura, Junta de Andalucía, the Spanish Ministry of Science and Innovation, project CGL2010-17183 and the CSIC project 201230E125

11 páginas.-- 2 figuras.-- 6 tablas.-- 65 referencias, The discovery of new antibiotics and other bioactive microbial metabolites is a priority given the frequency of the emerging multi-drug resistant pathogenic microorganisms. Thus, scientists are searching for new antibiotics in microorganisms isolated from extreme habitats such as caves. In the present study, we aimed to perform the first analysis on culturable microorganisms in the Chaabe Cave (Algeria), and to test the antimicrobial activities of the isolates (Streptomyces spp. and Penicillium spp.). The potential for antimicrobial activity of 47 strains of actinomycetes and 23 strains of fungi were tested on Candida albicans, Staphylococcus aureus, Micrococcus luteus, Listeria monocytogenes, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. The identification of the most active actinomycetes strains by 16S rRNA gene sequence analysis revealed that these isolates were exclusively affiliated to the genus Streptomyces. On the other hand, the fungi were determined by phylogenetic analysis based on the ITS region or on the β tubulin gene and were affiliated to the genera Readeriella, Cladosporium, Aspergillus, Penicillium, Beauveria, Alternaria, Rhizopus, and Rhizomucor. The strains showed strong inhibitory activity against pathogenic microorganisms and the diameters of the inhibition zones vary between 7.5 and 34 mm for Streptomyces strains, and between 6.5 and 19.50 mm for Penicillium strains. The data indicated that the majority (72.86%) of the 70 isolates were active against at least one of the tested microorganisms. The production of nonpolyenic antifungal substances by active Streptomyces isolates was investigated using several criteria (antibacterial activity, ergosterol inhibition, and UV-visible spectra) of active extracts. The results were promising and showed that the metabolites produced by the actinomycete strains do not have a UV-visible spectrum characteristic of a polyenic structure. The Chaabe Cave possesses a diversity of microorganisms that could lead to new antibiotics necessary in the fight against drug-resistant pathogens and warrant further study

22 páginas.-- 6 figuras.-- 115 referencias.-- Additional Supporting Information may be found in the online version of this article: http://dx.doi.org/10.1111/sed.12431, Subsurface granitic environments are scarce and poorly investigated. A multi‐disciplinary approach was used to characterize the abundant moonmilk deposits and associated microbial communities coating the granite walls of the 16th Century Paranhos spring water tunnel in Porto city (north‐west Portugal). It is possible that this study is the first record of moonmilk in an urban subsurface granitic environment. The morphology and texture, mineralogical composition, stable isotope composition and microbial diversity of moonmilk deposits have been studied to infer the processes of moonmilk formation. These whitish secondary mineral deposits are composed of very fine needle‐fibre calcite crystals with different morphologies and density. Calcified filaments of fungal hyphae or bacteria were distinguished by field emission scanning electron microscopy. Stable isotope analysis revealed a meteoric origin of the needle‐fibre calcite, with an important contribution of atmospheric CO2, soil respiration and urn:x-wiley:00370746:media:sed12431:sed12431-math-0001 from weathering of Ca‐bearing minerals. The DNA‐based analyses revealed the presence of micro‐organisms related to urban contamination, including Actinobacteria, mainly represented by Pseudonocardia hispaniensis, Thaumarchaeota and Ascomycota, dominated by Cladosporium. This microbial composition is consistent with groundwater pollution and contamination sources of the overlying urban area, including garages, petrol stations and wastewater pipeline leakage, showing that the Paranhos tunnel is greatly perturbed by anthropogenic activities. Whether the identified micro‐organisms are involved in the formation of the needle‐fibre calcite or not is difficult to demonstrate, but this study evidenced both abiotic and biogenic genesis for the calcite moonmilk in this subsurface granitic environment., The authors acknowledge the Spanish Ministry of Economy, Industry and Competitiveness (MINEICO, project CGL2011-2569) and the Portuguese Foundation for Science and Technology, FCT (UID/GEO/04035/2013, UID/ECI/04028/2013, PEst-OE/CTE/UI0098/2011) and the LABCARGA| ISEP re-equipment program (IPP-ISEP|PAD’2007/ 08) for financial support. AZM thanks MINEICO for the ‘Juan de la Cierva – Incorporación’ postdoctoral contract (IJCI-2014-20443). PMMS thanks the Spanish Ministry of Science and Innovation for his contract associated with the ‘Research Programme in Technologies for the Assessment and Conservation of Cultural Heritage’ (TCP CSD2007-0005

18 páginas._ 3 figuras.- 1 tabla.- 102 referencias, Of the several critical challenges present in environmental microbiology today, one is the assessment of the contribution of microorganisms in the carbon cycle in the Earth-climate system. Karstic subterranean ecosystems have been overlooked until recently. Covering up to 25% of the land surface and acting as a rapid CH4 sink and alternately as a CO2 source or sink, karstic subterranean ecosystems play a decisive role in the carbon cycle in terms of their contribution to the global balance of greenhouse gases. Recent data indicate that microbiota must play a significant ecological role in the biogeochemical processes that control the composition of the subterranean atmosphere, as well as in the availability of nutrients for the ecosystem. Nevertheless, there are still essential gaps in our knowledge concerning the budgets of greenhouse gases at the ecosystem scale and the possible feedback mechanisms between environmental-microclimatic conditions and the rates and type of activity of microbial communities in subterranean ecosystems. Another challenge is searching for bioactive compounds (antibiotics) used for treating human diseases. At present, there is a global health emergency and a strong need for novel biomolecules. In recent decades, great research efforts have been made to extract antibiotics from marine organisms. More recently, caves have been receiving considerable attention in search of novel antibiotics. Cave methanotrophic and heterotrophic bacteria are producers of bioactive compounds and may be potential sources of metabolites with antibacterial, antifungal or anticancer activities of interest in pharmacological and medical research, as well as enzymes with a further biotechnological use. Here we also show that bacteria isolated from mines, a still unexplored niche for scientists in search of novel compounds, can be a source of novel secondary metabolites, Financial support was obtained through project 0483_PROBIOMA_5_E, co-financed by the European Regional Development Fund within the framework of the Interreg V-A Spain-Portugal program (POCTEP) 2014–2020. This work was also supported by the Spanish Ministry of Economy and Competitiveness through projects CGL2016-75590-P and PID2019-110603RB-I00, AEI/FEDER, UE.

2 páginas.- 1 tabla.- 15 referencias.- Genome Sequences, Two Streptomyces strains were isolated from a lava tube in La Palma, Canary Islands. Genomic analyses suggest that the two strains could belong to the same species. Here, we report the draft genomes for these bacterial strains., Financial support was obtained through project 0483_PROBIOMA_5_E, cofinanced by the European Regional Development Fund within the framework of the Interreg V-A Spain-Portugal program (POCTEP) (2014 to 2020).

14 páginas.- 5 firuras.- 57 referencias.- Supplementary Materials: The following are available online at https://www.mdpi.com/article/10.3390/app11115027/s1, The aerobiology of caves in Southern Spain possesses special characteristics, different from caves located in Northern Spain. Previous studies demonstrated the influence of outdoor air on caves in the north and the existence of two different patterns, depending on the season. In summer there is an abundance of Ascomycota, whereas in winter Basidiomycota predominates, which are related to the periods of stagnation and ventilation, respectively. In caves in Southern Spain the presence of airborne Basidiomycota is scarce and Ascomycota represents the main group of fungi widely distributed across the caves in all seasons. The most characteristic features were the abundant presence of entomopathogenic fungi (Beauveria bassiana, Parengyodontium album, Pochonia chlamydosporia, Leptobacillium symbioticum, Leptobacillium leptobactrum) and Cladosporium cladosporioides in Cueva del Tesoro, Cueva de Ardales and Gruta de las Maravillas. However, the presence of yeasts of the genera Cutaneotrichosporon, Trichosporon, Cryptococcus, Naganishia, Cystobasidium, Microstroma and Phragmotaenium was exclusive to Gruta de las Maravillas. Fungal hazard in the three show caves were determined using an ecological indicator based on the concentration of spores in cave air. © 2021 by the authors. Licensee MDPI, Basel, Switzerland., Funding: This research was funded by Junta de Andalucia, grant number RNM-5137. I.D.-M. acknowledges the pre-doctoral grant associated to project RNM-5137.

24 páginas.- 14 figuras.- 5 tablas.- 136 referencias.- Supplementary data to this article can be found online athttps://doi.org/10.1016/j.scitotenv.2020.141218, The migration of geogenic gases in continental areas with geothermal activity and active faults is an important process releasing greenhouse gases (GHG) to the lower troposphere. In this respect, caves in hypogenic environments are natural laboratories to study the compositional evolution of deep-endogenous fluids through the Critical Zone. Vapour Cave (Alhama, Murcia, Spain) is a hypogenic cave formed by the upwelling of hydrothermal CO2-rich fluids. Anomalous concentrations of N2O and NO2 were registered in the cave's subterranean atmosphere, averaging ten and five times the typical atmospheric backgrounds, respectively. We characterised the thermal conditions, gaseous compositions, sediments, and microbial communities at different depths in the cave. We did so to understand the relation between N-cycling microbial groups and the production and transformation of nitrogenous gases, as well as their coupled evolution with CO2 and CH4 during their migration through the Critical Zone to the lower troposphere. Our results showed an evident vertical stratification of selected microbial groups (Archaea and Bacteria) depending on the environmental parameters, including O2, temperature, and GHG concentration. Both the N2O isotope ratios and the predicted ecological functions of bacterial and archaeal communities suggest that N2O and NO2 emissions mainly depend on the nitrification by ammonia-oxidising microorganisms. Denitrification and abiotic reactions of the reactive intermediates NH2OH, NO, and NO2− are also plausible according to the results of the phylogenetic analyses of the microbial communities. Nitrite-dependent anaerobic methane oxidation by denitrifying methanotrophs of the NC10 phylum was also identified as a post-genetic process during migration of this gas to the surface. To the best of our knowledge, our report provides, for the first time, evidence of a niche densely populated by Micrarchaeia, which represents more than 50% of the total archaeal abundance. This raises many questions on the metabolic behaviour of this and other archaeal phyla. © 2020 Elsevier B.V., This work was supported by the Spanish Ministry of Economy and Competitiveness through projects PID2019-110603RB-I00 , CGL2016-78318-C2-1R and CGL2016-78318-C2-2R AEI/FEDER/UE, and with the scientific and technical contribution of the following projects: CGL2016-75590-P with ERDF funds, CGL2017-83931-C3-2-P and CGL2017-87216-C4-1-R , AEI / FEDER , UE. S. Cuezva was funded by the European Union's Horizon 2020 - Research and Innovation Framework Programme under the Marie Skłodowska-Curie grant agreement No 844535 — MIFLUKE. N. Otero was funded by the Serra Húnter Fellowship ( Generalitat de Catalunya , Spain). We thank to GERA-group of the Fire-fighters Service of Madrid Autonomous Region for the essential work on installing the system of tubes for air sampling and the Council of “Alhama de Murcia” for their technical assistance during fieldwork.

13 páginas.- 5 figuras.- 2 tablas.- 39 referencias, Cyanobacteria and microalgae are usually found in speleothems, rocks and walls of show caves exposed to artificial lighting. These microorganisms develop as biofilms coating the mineral surfaces and producing aesthetic, physical and chemical deterioration. A wide number of physical, chemical and environmental-friendly methods have been used for controlling the biofilms with different results. Natural biological control has been suggested by some authors as a theoretical approach but without direct evidence or application. Here we report the finding of a natural biological control of phototrophic biofilms on the speleothems of Nerja Cave, Malaga, Spain. The formation of plaques or spots where the phototrophic microorganisms disappeared can be assumed on the basis of processes of predation of bacteria, amoebas and some other organisms on the phototrophic biofilms. This study aims at investigating the potentialities of the biological control of phototrophic biofilms in caves, but the originality of these data should be confirmed in future studies with a larger number of biofilm samples in different ecological scenarios.

33 páginas.- 14 figuras.- 3 tablas.- 97 referencias.- Supporting information, Fetida Cave is an active sulfuric acid cave influenced by seawater, showing abundant microbial communities that organize themselves under three main different morphologies: water filaments, vermiculations and moonmilk deposits. These biofilms/deposits have different cave distribution, pH, macro- and microelement and mineralogical composition, carbon and nitrogen content. In particular, water filaments and vermiculations had circumneutral and slightly acidic pH, respectively, both had abundant organic carbon and high microbial diversity. They were rich in macro- and microelements, deriving from mineral dissolution, and, in the case of water filaments, from seawater composition. Vermiculations had different color, partly associated with their mineralogy, and unusual minerals probably due to trapping capacities. Moonmilk was composed of gypsum, poor in organic matter, had an extremely low pH (0–1) and low microbial diversity. Based on 16S rRNA gene analysis, the microbial composition of the biofilms/deposits included autotrophic taxa associated with sulfur and nitrogen cycles and biomineralization processes. In particular, water filaments communities were characterized by bacterial taxa involved in sulfur oxidation and reduction in aquatic, aphotic, microaerophilic/anoxic environments (Campylobacterales, Thiotrichales, Arenicellales, Desulfobacterales, Desulforomonadales) and in chemolithotrophy in marine habitats (Oceanospirillales, Chromatiales). Their biodiversity was linked to the morphology of the water filaments and their collection site. Microbial communities within vermiculations were partly related to their color and showed high abundance of unclassified Betaproteobacteria and sulfur-oxidizing Hydrogenophilales (including Sulfuriferula), and Acidiferrobacterales (including Sulfurifustis), sulfur-reducing Desulfurellales, and ammonia-oxidizing Planctomycetes and Nitrospirae. The microbial community associated with gypsum moonmilk showed the strong dominance (>60%) of the archaeal genus Thermoplasma and lower abundance of chemolithotrophic Acidithiobacillus, metal-oxidizing Metallibacterium, Sulfobacillus, and Acidibacillus. This study describes the geomicrobiology of water filaments, vermiculations and gypsum moonmilk from Fetida Cave, providing insights into the microbial taxa that characterize each morphology and contribute to biogeochemical cycles and speleogenesis of this peculiar seawater-influenced sulfuric acid cave. © 2019 D’Angeli et al., C work was supported by UNIBO (Ricerca Fondamentale e Orientata—RFO) and the Rectorate of UNIBO. Funding for microbial analyses was provided by Europlanet 2020 15-EPN1-029 and 17-EPN3-021 grants. Europlanet 2020 RI has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654208. Further funding was provided by the Spanish project MINECO CGL2016-75590-P with ERDF funds.

2 páginas.- 17 referencias.- Data availability. This whole-genome shotgun project has been deposited at DDBJ/ENA/GenBank under the accession number VSZQ00000000. The version described in this paper is the first version, VSZQ01000000. BioProject and raw data are available at the accession numbers PRJNA562075 and SRR10059654, respectively., Streptomyces parvus strain C05 was isolated from the walls of a Roman tomb located in Carmona, Seville, Spain. Subsequent studies determined the capability of this strain for producing granaticins. Here, we report the 8.7-Mbp draft genome sequence for this bacterium., Financial support was obtained through project 0483_PROBIOMA_5_E, cofinanced by the European Regional Development Fund within the framework of the Interreg V-A Spain-Portugal program (POCTEP) 2014 –2020.

Póster presentado en EGU 2019, Viena (Austria) 7 al 12 de abril de 2019. Puede ver el Abstract en https://meetingorganizer.copernicus.org/EGU2019/EGU2019-8949.pdf, Etruscan and Roman necropolises are cemeteries with different types of burial practices, which are remarkable for their magnificent mural paintings. The conservation of these paintings is difficult, mainly derived from environmental factors and the opening of the tombs to public visits. One of the most complex phenomena observed on these sites is biodeterioration. The Circular Mausoleum tomb (Roman Necropolis of Carmona, Seville, Spain) is characterized by a heavy colonization of phototrophic microorganisms on the walls and ceiling. In addition, some areas near the ceiling exhibited an important number of violet stains of unknown origin. Previously, Agarossi (1994) found similar violet stains, attributed to streptomycetes, in two Etruscan tombs. However, no data on the species involved or the chemical structure of the pigments were reported. Here we show that the violet stains observed in the Circular Mausoleum are produced by a strain of the actinobacterium Streptomyces isolated from the mortar walls, and able to synthesize the same violet pigment in the laboratory. Streptomyces parvus MC05 was identified after whole genome study by means of Next Generation Sequencing methods. Pairwise comparisons carried out for genomes of the type strain of S. parvus DSM40348T and the MC05 strain were performed using Jspecies service. While results observed for ANIb, ANIm and Tetra indexes indicated that both strains belong to the same species, the S. parvus MC05 strain differs from the DSM20348T type strain in genome size and secondary metabolites production. AntiSMASH analysis implemented for both strains showed that the S. parvus MC05, isolated from the tomb, presents the capacity of synthesize bioactive compounds which were absents in the type strain. HPLC-MS of the culture extracts from S. parvus MC05 showed the production of three main granaticin derivatives (dihydrogranaticin A, granaticin A and granaticin B) in addition to minor products of other granaticin analogues. Granaticin pigments exhibited antibacterial activity, which justified the low number of clones of Gram positive bacteria found in the whole microbial community study. Gram negative bacteria were not affected (DominguezMoñino et al. 2017). To conclude, the origin of the violet stains in the walls of the Circular Mausoleum is the presence of S. parvus MC05, a member of the complex microbial community thriving on the tomb. In growing periods (rainy season) the bacterium excretes the soluble violet granaticins, compounds with a benzoisochromanequinone structure, which diffuses to the mortar and surrounding substrata in wetting periods., References - Agarossi, G. 1994. In Studi e Ricerche sulla Conservazione delle Opere d’Arte Dedicati alla Memoria di Marcello - Paribeni. F. Guidobaldi (ed.), CNRS, pp. 1−11. - Dominguez-Moñino, I. et al. 2017. Science of the Total Environment 598, 889-899.

19 páginas.-- 2 figuras.-- 2 tablas.-- 43 referencias, Two Gram-positive, catalase-positive, oxidase-negative, motile, endospore-forming, rod-shaped bacteria, designated as 0911MAR22V3T and 0911TES10J4, were isolated from air samples collected in two show caves, located in Andalusia, Southern Spain. Phylogenetic analysis based on 16S rRNA gene sequences indicated that both strains were indistinguishable and they were most closely related to Bacillus humi DSM 16318T (98%). DNA-DNA hybridization values of the strain 0911MAR22V3T with respect to strain 0911TES10J4 and B. humi DSM 16318T were 76.8% (73.9%, reciprocal) and 56.9% (63.3%, reciprocal analysis), respectively. Whole genome average nucleotide identity (ANI) values of both strains were in the threshold value for species delineation and less than 85% with B. humi. Strains 0911MAR22V3T and 0911TES10J4 grew at 10-47. °C (optimum 37. °C), at pH 6-9.5 and with 0-8% (w/v) NaCl (optimum 1%). In both strains the dominant isoprenoid quinone was MK-7, the major cellular polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and two more phospholipids, the predominant fatty acids were iso-C15:0 and anteiso-C15:0 and the DNA G + C content was 38. mol%. On the basis of their phylogenetic relatedness and their phenotypic and genotypic features, the strains 0911MAR22V3T and 0911TES10J4 should be attributed to a novel species within the genus Bacillus, for which the name Bacillus onubensis sp. nov. is proposed. The type strain is 0911MAR22V3T (=LMG 27963T = CECT 8479T); and strain 0911TES10J4 (CECT 8478) is a reference strain., This study was supported by the project RNM 5137, Consejería de Innovación, Ciencia y Empresa, Junta de Andalucía, co-financed by 2007-2013 FEDER programme

11 páginas.-- 2 figuras.-- 41 referencias.-- Conferencia presentada en el Sexto Congreso Español sobre Cuevas Turísticas, celebrado en Nerja (Málaga), en septiembre/octubre de 2016.-- Descarga de las Actas en http://www.cuevasturisticas.es/cuevatur/docs/2016/pdf/LibroCuevastur2016.pdf, [ES]: La geomorfología del medio subterráneo depende de su historia geológica, y de los fenómenos que lo modelan, como la erosión y otros agentes externos. Además, sobre los sedimentos, las paredes o los espeleotemas de cuevas se desarrollan poblaciones de microorganismos que modifican la superficie mineral. Así, la colonización de este medio estará en función de las condiciones ambientales, del grupo de microorganismos en cuestión y de la biorreceptividad de los sustratos. Las cuevas se consideran espacios especializados que se caracterizan por una temperatura uniforme, elevada humedad y escasos recursos nutricionales y energéticos. Las cuevas turísticas presentan mayor disponibilidad de energía, generada por la luz artificial y la entrada de materia orgánica, y favorecen la presencia de un mayor número de organismos fotosintéticos y heterótrofos. El desarrollo de microorganismos sobre las paredes y los espeleotemas de las cuevas pueden producir procesos de biodeterioro, es decir, cambios indeseables en el sustrato. En este trabajo se presenta la información obtenida sobre la microbiota que coloniza espeleotemas iluminados de dos cuevas turísticas, la Cueva de Nerja y la Cueva del Tesoro (Málaga), mediante el empleo combinado de la microscopía y del análisis molecular. Los resultados ponen de manifiesto que los microorganismos se organizan en comunidades estructurales complejas denominadas biofilms. El empleo de la microscopía ha permitido conocer la composición del sustrato y su relación con el biofilm, así como observar procesos de biodeterioro relacionados con cambios físicos y químicos del sustrato tales como decoloración, pérdida de consistencia, ruptura y disolución. En relación con la composición de los biofilms, se ha observado una biodiversidad dominada por cianobacterias y microalgas, junto con actinobacterias, proteobacterias, arqueas, hongos e incluso protozoos y pequeños artrópodos. El análisis molecular revela la presencia de nuevas especies de microorganismos en ambas cuevas. El conocimiento de estas comunidades, así como sus mecanismos de biodeterioro permite el diseño de medidas preventivas y correctoras destinadas al control y a una adecuada conservación del patrimonio natural y cultural de ambas cuevas., [EN]: The geomorphology of the subterranean environment depends on its geological history, and phenomena such as erosion and other external agents. Moreover, in the caves the development of microorganisms can change the surface of sediments, walls and speleothems. Therefore, the colonization of a cave will depend on the environmental conditions, the type of microorganisms involved and the substrata bioreceptivity. Caves are considered specialized areas characterized by a uniform temperature, high humidity and low nutritional and energy resources. Visited caves have more available energy, produced by artificial lighting and the input of organic matter, and these conditions allow the growth of photosynthetic and heterotrophic organisms. The development of microorganisms on the cave walls and speleothems may produce biodeterioration, i.e., undesirable changes in the substratum. This work provides information on the microbiota that colonizes illuminated speleothems in two tourist caves, Nerja and Tesoro (Málaga), through the combined use of optical and electron microscopy, together with molecular analysis. The results showed that, in both caves, microorganisms are organized into complex structural communities called biofilms. The microscopic approach provides data on the substratum composition and its relationship with the biofilm. Biodeterioration processes related to physical and chemical changes of the substratum such as discoloration, loss of consistency, breaking and dissolution, were also observed. The biofilms were dominated by cyanobacteria and microalgae together with actinobacteria, proteobacteria, archaea, protozoa, fungi and even small arthropods. Moreover, molecular analysis revealed the presence of new species of microorganisms in both caves. Knowledge about these communities and their mechanisms of biodeterioration allows the design of preventive and corrective actions, according with a proper conservation of natural and cultural heritage of both caves.

12 páginas.-- 5 gráficos.-- 6 referencias.-- Conferencia presentada en el Sexto Congreso Español sobre Cuevas Turísticas, celebrado en Nerja (Málaga), en septiembre/octubre de 2016.-- Descarga de las Actas en http://www.cuevasturisticas.es/cuevatur/docs/2016/pdf/LibroCuevastur2016.pdf, [ES]: La zona arqueológica de la Garma (Cantabria) forma parte de un gran complejo kárstico activo con varios niveles de galerías de desarrollo horizontal interconectados por conductos verticales. La Garma alberga un conjunto arqueológico excepcional que incluye un magnífico conjunto de arte parietal y suelos paleolíticos en un asombroso estado de conservación, así como valiosísimas evidencias del comportamiento simbólico de los cazadores-recolectores del Pleistoceno. Sus valores patrimoniales le han hecho merecedora de ser incluida en la Lista del Patrimonio Mundial de la UNESCO en el año 2008. La conservación de este enclave es en todo momento prioritaria y recientemente se ha puesto en marcha un programa de conservación preventiva que tiene como objetivo fundamental el conocimiento del ecosistema subterráneo y del impacto de la presencia humana en el medio subterráneo, a los efectos tanto de la propia gestión e investigación de la cavidad como ante una eventual apertura al público en condiciones de máxima seguridad. El funcionamiento de un sistema kárstico subterráneo como el de La Garma, con varios niveles de desarrollo y conectado directamente con el nivel freático activo, implica un complejo movimiento de materia (agua, masas de aire y aerosoles) y energía. Para alcanzar un adecuado conocimiento de su dinámica ambiental, desde febrero de 2015 se está llevando a cabo un estudio multidisciplinar mediante el empleo de metodologías específicas para cada interfase involucrada: microclima (cavidad en tres niveles internos del karst y atmósfera externa), hidroquímica (agua de infiltración y condensación), geoquímica isotópica (aire, suelo) y contaminación microbiológica (aire, suelo, roca). Los primeros datos muestran cambios estacionales muy marcados en el patrón de ventilación general de la cavidad, con mayor tasa de renovación de aire en la época invernal, y una estabilidad ambiental muy diferenciada entre zonas, con algunos sectores aislados del régimen general de circulación natural del aire., [EN]: The archaeological site of the Garma (Cantabria) is part of an active karst system with several levels of galleries interconnected by vertical shafts. La Garma houses an exceptional archaeological heritage that includes magnificent examples of Palaeolithic cave art and settlement floors in an amazing state of preservation, as well as valuable evidence of symbolic behavior of Pleistocene hunter-gatherers. Its heritage values have made it worthy of their inclusion on the World Heritage List of UNESCO in 2008. The conservation of this site is a priority and it has been recently launched a program of preventive conservation. The main objective of this project is to achieve a better knowledge of the underground ecosystem and the impact of human presence in the underground microenvironment, both for purposes of sound management and research of the cavity as well as for a hypothetical opening to the public in the future. The underground karst system of La Garma, with various levels of galleries and directly connected with active water table, involves a complex movement of matter (water, air masses and aerosols) and energy. To achieve an adequate knowledge of environmental dynamics, our research group is conducting a multidisciplinary study since February 2015 by employing specific methodologies for each interface involved: microclimate (cavity in three internal levels of karst and external atmosphere), hydrochemical (water infiltration and condensation), isotope geochemistry (air, soil) and microbiological contamination (air, soil, rock). Early data show very marked seasonal changes in the general ventilation pattern of the cavity (air renewal in winter) and areas with different microenvironmental stability, including sectors with a greater degree of isolation from the regime of general circulation of air in the cavity., Estos estudios están financiados por un contrato de apoyo tecnológico financiado por el Gobierno de Cantabria – Consejería de Educación, Cultura y Deporte a través de la Sociedad Regional de Educación, Cultura y Deporte, S.L. para la ejecución del proyecto Monitorización microambiental de la Cueva de La Garma. Asimismo se enmarcan en el proyecto CGL2013-43324-R y se han beneficiado de la ayuda para un contrato (SC) del programa Torres Quevedo (PTQ 13-06296), ambos financiados por el Ministerio de Economía y Competitividad.