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Plant–soil biodiversity interactions are fundamental for the functioning of terrestrial ecosystems. Yet, the existence of a set of globally distributed topsoil microbial and small invertebrate organisms consistently associated with land plants (i.e., their consistent soil-borne microbiome), together with the environmental preferences and functional capabilities of these organisms, remains unknown. We conducted a standardized field survey under 150 species of land plants, including 58 species of bryophytes and 92 of vascular plants, across 124 locations from all continents. We found that, despite the immense biodiversity of soil organisms, the land plants evaluated only shared a small fraction (less than 1%) of all microbial and invertebrate taxa that were present across contrasting climatic and soil conditions and vegetation types. These consistent taxa were dominated by generalist decomposers and phagotrophs and their presence was positively correlated with the abundance of functional genes linked to mineralization. Finally, we showed that crossing environmental thresholds in aridity (aridity index of 0.65, i.e., the transition from mesic to dry ecosystems), soil pH (5.5; i.e., the transition from acidic to strongly acidic soils), and carbon (less than 2%, the lower limit of fertile soils) can result in drastic disruptions in the associations between land plants and soil organisms, with potential implications for the delivery of soil ecosystem processes under ongoing global environmental change.

Phenotypic variability is a successful strategy in lichens for colonizing different habitats. Vagrancy has been reported as a specific adaptation for lichens living in steppe habitats around the world. Among the facultatively vagrant species, the cosmopolitan Cetraria aculeata apparently forms extremely modified vagrant thalli in steppe habitats of Central Spain. The aim of this study was to investigate whether these changes are phenotypic plasticity (a single genotype producing different phenotypes), by characterizing the anatomical and ultrastructural changes observed in vagrant morphs, and measuring differences in ecophysiological performance. Methods Specimens of vagrant and attached populations of C. aculeata were collected on the steppes of Central Spain. The fungal internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GPD) and the large sub-unit of the mitochondrial ribosomal DNA (mtLSUm), and the algal ITS and actin were studied within a population genetics framework. Semi-thin and ultrathin sections were analysed by means of optical, scanning electron and transmission electron microscopy. Gas exchange and chlorophyll fluorescence were used to compare the physiological performance of both morphs. Key Results and Conclusions Vagrant and attached morphs share multilocus haplotypes which may indicate that they belong to the same species in spite of their completely different anatomy. However, differentiation tests suggested that vagrant specimens do not represent a random sub-set of the surrounding population. The morphological differences were related to anatomical and ultrastructural differences. Large intercalary growth rates of thalli after the loss of the basal–apical thallus polarity may be the cause of the increased growth shown by vagrant specimens. The anatomical and morphological changes lead to greater duration of ecophysiological activity in vagrant specimens. Although the anatomical and physiological changes could be chance e, Ministerio de Ciencia e Innovación, Gobierno de España, German Science Foundation, Depto. de Farmacología, Farmacognosia y Botánica, CAI Ciencias de la Tierra y Arqueometría, TRUE, pub

The green algal lichen Placopsis pycnotheca was identified at Pia and Marinelli glaciers (Isla Grande of Tierra de Fuego, Chile) as a primary colonizer of bare soil in areas close to the front of the glacier or around small ponds created after glacier retreatment. Electron microscopy study showed that P. pycnotheca formed a thick hypothallus within which hyphae and their extracellular polymeric substances bind numerous soil particles. This structure augments water holding and soil stabilization capacities and constitutes an early stage in soil crust development. In addition, numerous cephalodia are formed within the hypothallus and subsequently develop upwards towards the thallus surface, sometimes before the formation of squamules with green algae. These anatomical and morphological strategies together with physiological properties such as the long photosynthetic activity period (measured in the laboratory) help explain its pioneering role as a colonizer and its apparently high growth rate., Ministerio de Ciencia e Innovación, Gobierno de España, Depto. de Farmacología, Farmacognosia y Botánica, Fac. de Farmacia, TRUE, pub

This study explores the diversity of photobionts associated with the Mediterranean lichen-forming fungus Cladonia subturgida. For this purpose, we sequenced the whole ITS rDNA region by Sanger using a metabarcoding method for ITS2. A total of 41 specimens from Greece, Italy, France, Portugal, and Spain were studied. Additionally, two specimens from Spain were used to generate four cultures. Our molecular studies showed that the genus Myrmecia is the main photobiont of C. subturgida throughout its geographic distribution. This result contrasts with previous studies, which indicated that the main photobiont for most Cladonia species is Asterochloris. The identity of Myrmecia was also confirmed by ultrastructural studies of photobionts within the lichen thalli and cultures. Photobiont cells showed a parietal chloroplast lacking a pyrenoid, which characterizes the species in this genus. Phylogenetic analyses indicate hidden diversity within this genus. The results of amplicon sequencing showed the presence of multiple ASVs in 58.3% of the specimens studied.

Soil mosses are among the most widely distributed organisms on land. Experiments and observations suggest that they contribute to terrestrial soil biodiversity and function, yet their ecological contribution to soil has never been assessed globally under natural conditions. Here we conducted the most comprehensive global standardized field study to quantify how soil mosses influence 8 ecosystem services associated with 24 soil biodiversity and functional attributes across wide environmental gradients from all continents. We found that soil mosses are associated with greater carbon sequestration, pool sizes for key nutrients and organic matter decomposition rates but a lower proportion of soil-borne plant pathogens than unvegetated soils. Mosses are especially important for supporting multiple ecosystem services where vascular-plant cover is low. Globally, soil mosses potentially support 6.43 Gt more carbon in the soil layer than do bare soils. The amount of soil carbon associated with mosses is up to six times the annual global carbon emissions from any altered land use globally. The largest positive contribution of mosses to soils occurs under a high cover of mat and turf mosses, in less-productive ecosystems and on sandy and salty soils. Our results highlight the contribution of mosses to soil life and functions and the need to conserve these important organisms to support healthy soils.

Soil contamination is one of the main threats to ecosystem health and sustainability. Yet little is known about the extent to which soil contaminants differ between urban greenspaces and natural ecosystems. Here we show that urban greenspaces and adjacent natural areas (i.e., natural/semi-natural ecosystems) shared similar levels of multiple soil contaminants (metal(loid)s, pesticides, microplastics, and antibiotic resistance genes) across the globe. We reveal that human influence explained many forms of soil contamination worldwide. Socio-economic factors were integral to explaining the occurrence of soil contaminants worldwide. We further show that increased levels of multiple soil contaminants were linked with changes in microbial traits including genes associated with environmental stress resistance, nutrient cycling, and pathogenesis. Taken together, our work demonstrates that human-driven soil contamination in nearby natural areas mirrors that in urban greenspaces globally, and highlights that soil contaminants have the potential to cause dire consequences for ecosystem sustainability and human wellbeing.

Soils are the foundation of all terrestrial ecosystems1. However, unlike for plants and animals, a global assessment of hotspots for soil nature conservation is still lacking2. This hampers our ability to establish nature conservation priorities for the multiple dimensions that support the soil system: from soil biodiversity to ecosystem services. Here, to identify global hotspots for soil nature conservation, we performed a global field survey that includes observations of biodiversity (archaea, bacteria, fungi, protists and invertebrates) and functions (critical for six ecosystem services) in 615 composite samples of topsoil from a standardized survey in all continents. We found that each of the different ecological dimensions of soils—that is, species richness (alpha diversity, measured as amplicon sequence variants), community dissimilarity and ecosystem services—peaked in contrasting regions of the planet, and were associated with different environmental factors. Temperate ecosystems showed the highest species richness, whereas community dissimilarity peaked in the tropics, and colder high-latitudinal ecosystems were identified as hotspots of ecosystem services. These findings highlight the complexities that are involved in simultaneously protecting multiple ecological dimensions of soil. We further show that most of these hotspots are not adequately covered by protected areas (more than 70%), and are vulnerable in the context of several scenarios of global change. Our global estimation of priorities for soil nature conservation highlights the importance of accounting for the multidimensionality of soil biodiversity and ecosystem services to conserve soils for future generations.

We present here a complete system for metagenomic analysis that allows performing the sequencing and analysis of a medium-size metagenome in less than one day. This unprecedented development was possible due to the conjunction of state-of-the art experimental and computational advances: a portable laboratory suitable for DNA extraction and sequencing with nanopore technology; the powerful metagenomic analysis pipeline SqueezeMeta, capable to provide a complete analysis in a few hours and using scarce computational resources; and tools for the automatic inspection of the results via a graphical user interface, that can be coupled to a web server to allow remote visualization of data (SQMtools and SQMxplore). We have tested the feasibility of our approach in the sequencing of the microbiota associated to volcanic rocks in La Palma, Canary Islands. Also, we did a two-day sampling campaign of marine waters in which the results obtained the first day guided the experimental design of the second day. This system offers the possibility of prospecting any habitat in a quick way, obtaining both taxonomic and functional information about the target microbiome.

The development of diagnostic methods to accurately assess the effects of treatments on lithobiont colonization remains a challenge for the conservation of Cultural Heritage monuments. In this study, we tested the efficacy of biocide-based treatments on microbial colonization of a dolostone quarry, in the short and long-term, using a dual analytical strategy. We applied a metabarcoding approach to characterize fungal and bacterial communities over time, integrated with microscopy techniques to analyze the interactions of microorganisms with the substrate and evaluate the effectiveness. These communities were dominated by the bacterial phyla Actinobacteriota, Proteobacteria and Cyanobacteria, and the fungal order Verrucariales, which include taxa previously reported as biodeteriogenic agents and observed here associated with biodeterioration processes. Following the treatments, changes over time in the abundance profiles depend on taxa. While Cyanobacteriales, Cytophagales and Verrucariales decreased in abundance, other groups, such as Solirubrobacteriales, Thermomicrobiales and Pleosporales increased. These patterns could be related not only to the specific effects of the biocide on the different taxa, but also to different recolonization abilities of those organisms. The different susceptibility to treatments could be associated with the inherent cellular properties of different taxa, but differences in biocide penetration to endolithic microhabitats could be involved. Our results demonstrate the importance of both removing epilithic colonization and applying biocides to act against endolithic forms. Recolonization processes could also explain some of the taxon-dependent responses, especially in the long-term. Taxa showing resistance, and those benefiting from nutrient accumulation in the form of cellular debris following treatments, may have an advantage in colonizing treated areas, pointing to the need for long-term monitoring of a wide range of taxa. This study

Lichens thrive in rocky coastal areas in temperate and cold regions of both hemispheres. Species of the genus Lichina, which form characteristic black fruiting thalli associated with cyanobacteria, often create distinguishable bands in the intertidal and supralittoral zones. The present study uses a comprehensive specimen dataset and four gene loci to (1) delineate and discuss species boundaries in this genus, (2) assess evolutionary relationships among species, and (3) infer the most likely causes of their current geographic distribution in the Northern and Southern hemispheres. A dated phylogeny describes the time frame in which extant disjunctions of species and populations were established. The results showed that the genus is integrated by four species, with Lichina pygmaea, L. confinis and the newly described L. canariensis from rocky seashores in the Canary Islands, occurring in the Northern Hemisphere, whereas L. intermedia is restricted to the Southern Hemisphere. Lichina intermedia hosted a much higher intraspecific genetic diversity than the other species, with subclades interpreted as specieslevel lineages by the different species delimitation approaches. However, a conservative taxonomic approach was adopted. This species showed a striking disjunct distribution between Australasia and southern South America. The timing for the observed interspecific and intraspecific divergences and population disjunctions postdated continental plate movements, suggesting that long-distance dispersal across body waters in the two hemispheres played a major role in shaping the current species distributions. Such ocean crossings were, as in L. canariensis, followed by speciation. New substitution rates for the nrITS of the genus Lichina were inferred using a tree spanning the major Ascomycota lineages calibrated using fossils. In conclusion, this work lays the foundation for a better understanding of the evolution through time and space of maritime lichens.

Correction to: Nature Communications, published online 27 March 2023 In the version of this article originally published, the current affiliation 25, “CEAZA, Universidad Católica del Norte, Coquimbo, Chile,” initially appeared as the last affiliation, offsetting all author footnotes from 25-39. The affiliation order has been restored in the article.

[Aim]: Lichens are often regarded as paradigms of mutualistic relationships. However, it is still poorly known how lichen-forming fungi and their photosynthetic partners in-teract at a community scale. We explored the structure of fungus-alga networks of in-teractions in lichen communities along a latitudinal transect in continental Antarctica. We expect these interactions to be highly specialized and, consequently, networks with low nestedness degree and high modularity.Location: Transantarctic Mountains from 76° S to 85° S (continental Antarctica)., [Time Period]: Present., [Major Taxa Studied]: Seventy-seven species of lichen-forming fungi and their photobionts., [Methods]: DNA barcoding of photobionts using nrITS data was conducted in 756 li-chen specimens from five regions along the Transantarctic Mountains. We built in-teraction networks for each of the five studied regions and a metaweb for the whole area. We explored the specialization of both partners using the number of partners a species interacts with and the specialization parameter d'. Network architecture parameters such as nestedness, modularity and network specialization parameter H2' were studied in all networks and contrasted through null models. Finally, we meas-ured interaction turnover along the latitudinal transect., [Results]: We recovered a total of 842 interactions. Differences in specialization be-tween partners were not statistically significant. Fungus-alga interaction networks showed high specialization and modularity, as well as low connectance and nested-ness. Despite the large turnover in interactions occurring among regions, network parameters were not correlated with latitude., [Main Conclusions]: The interaction networks established between fungi and algae in saxicolous lichen communities in continental Antarctica showed invariant properties along the latitudinal transect. Rewiring is an important driver of interaction turno-ver along the transect studied. Future work should answer whether the patterns ob-served in our study are prevalent in other regions with milder climates and in lichen communities on different substrates.

Porina is a widely distributed, species-rich genus of crustose, lichen-forming fungi, some with thalline outgrowths that have been recognized as isidia. We studied three taxa with thalli consisting chiefly of ascending isidioid structures occurring on trunks and branches of Taxodium in southwestern Florida, and provide details of their structure with light and electron microscopy. Two of these taxa we describe as new species: P. microcoralloides and P. nanoarbuscula. Genetic sequences (mtSSU) suggest that they are closely related to each other, yet they differ markedly in the size, morphology and anatomical organization of their isidioid branches as well as in the length of their ascospores. In the three Floridian taxa studied, the crustose portion of the thallus is partly endophloeodic and partly superficial, the latter often patchy, evanescent or inconspicuous, and completely lacks the differentiated anatomical organization characteristic of the isidioid structures arising from it. In Porina microcoralloides, the ascendant thallus consists of branched, coralloid inflated structures with phycobiont (Trentepohlia) unicells arranged at the periphery of a loose central medulla. Sparse fungal cells are interspersed and overlie the algal layer in places, but no differentiated cortex is present, leaving phycobiont cells more or less exposed at the surface. In the closely related Porina nanoarbuscula, the isidioid structures are much finer, more densely branched, and composed of a single, central file of roughly spherical Trentepohlia cells surrounded by a jacket of subglobose fungal cells. The ascospores of P. microcoralloides are more than twice the length of those of P. nanoarbuscula. Although thalli of these two Porina species occur in the same habitats and are sometimes found growing alongside each other, phylogenetic analysis of rbcL sequences suggest that they partner with distinct clades of Trentepohlia phycobionts. A third taxon examined, Porina cf. scabrida, is

I would like to personally introduce this issue because it includes two articles dedicated to our Spanish Microbiology Society colleagues Josep Casadesús and Rubén López, who passed away in 2022. Through the articles of their friends and colleagues Fernando Baquero and Ernesto García, we want to remember and pay tribute to them. Both were experts in bacterial genetics. Rubén López (1938–2022) studied gene transformation and transfection, as well as the use of phage lytic enzymes as therapeutic agents against multi-resistant bacterial infections. Josep Casadesús (1952–2022) covered various aspects of Salmonella biology and worked on transcriptional control by methylation of bacterial DNA., The merits and scientific relevance of both outstanding microbiologists are well known, but we want to highlight here the great relevance of these two scientists in the evolution and trajectory of this journal. Rubén López was the first Editor-Coordinator of the journal Microbiología SEM (precursor of the current International Microbiology), and later member of the editorial board of this journal. Josep Casadesús was also editor of International Microbiology for several years and a member of the editorial board until his death. Rubén and Josep, you will never be forgotten and will live on in our journal and in our hearts., I take this opportunity to also thank our readers, authors, expert reviewers and distinguished associated editors and editorial board for being part of International Microbiology, the official scientific journal of the Spanish Society of Microbiology.

Fungi are probably the most diverse group of eukaryotic organisms in the Antarctic continent and nearby archipelagos, and they dominate communities in either mild or harsh habitats. However, our knowledge of their global distribution ranges and the temporal origins of their Antarctic populations is rather limited or almost absent, especially for species that do not lichenize. We focused for the first time on elucidating the taxonomic identity and phylogenetic relationships of several Antarctic collections of the deadly fungal Basidiomycota genus Galerina. By using molecular sequence data from the universal fungal barcode and a dataset encompassing 178 specimens, the inferred phylogeny showed that the Antarctic specimens corresponded with the sub-cosmopolitan species Galerina marginata, Galerina badipes and Galerina fallax, and their most closely related intraspecific genetic lineages were from northern Europe and North America. We found that these species probably host Antarctic endemic intraspecific lineages. Furthermore, our dating analyses indicated that their Antarctic populations originated in the Pleistocene, a temporal frame that agrees with that proposed for the Antarctic colonization of plants such as the grass Deschampsia antarctica, mosses and some amphitropical lichens. Altogether, these findings converge on the same temporal scenario for the assembly of the most conspicuous terrestrial Antarctic plant and fungal communities.

Soil contamination is one of the main threats to ecosystem health and sustainability. Yet little is known about the extent to which soil contaminants differ between urban greenspaces and natural ecosystems. Here we show that urban greenspaces and adjacent natural areas (i.e., natural/semi-natural ecosystems) shared similar levels of multiple soil contaminants (metal(loid)s, pesticides, microplastics, and antibiotic resistance genes) across the globe. We reveal that human influence explained many forms of soil contamination worldwide. Socio-economic factors were integral to explaining the occurrence of soil contaminants worldwide. We further show that increased levels of multiple soil contaminants were linked with changes in microbial traits including genes associated with environmental stress resistance, nutrient cycling, and pathogenesis. Taken together, our work demonstrates that human-driven soil contamination in nearby natural areas mirrors that in urban greenspaces globally, and highlights that soil contaminants have the potential to cause dire consequences for ecosystem sustainability and human wellbeing.

Numerous distinct clades of lichen-forming fungi have independently specialized as foliicolous colonists of living leaves in the humid tropics and subtropics. Because of technical difficulties, the anatomy of their minute crustose thalli has not been compared in detail. In the present study, we applied SEM-BSE imaging to sectioned blocks of embedded thalli representing six lecanoralean taxa of foliicolous lichen-forming fungi with unicellular green algal partners. We compared our observations with those obtained in a previous study of foliicolous Gomphillaceae (Ostropales), which utilize a similar type of algal partner. The upper surface of the thalli was a mostly continuous layer of mycobiont hyphae of typical diameter, unlike the largely acellular epilayer found previously in the foliicolous Gomphillaceae. Byssoloma leucoblepharum was exceptional in lacking a covering layer altogether. Thalli were essentially unstratified, with algal symbionts not confined to any distinct layer. Whereas the prothallus of foliicolous Gomphillaceae was derived from the overlying epilayer, in the lecanoralean taxa examined here the prothallus was derived from hyphae continuous with either the upper surface of the thallus or the lower surface, or both. This finding suggests that the prothallus of lichen forming fungi may represent structures of developmentally different origins in different taxa.

We compiled, completed and revised eukaryotic species inventories present in terrestrial and freshwater ecosystems in Antarctica. This includes the first account for many groups of eukaryotic microorganisms. We also introduce a first catalogue of amplicon sequence variants (ASVs) of the prokaryote biodiversity. Available listings to data were searched, integrated, taxonomically harmonized and curated by experts to create comprehensive checklists of Antarctic organisms

Cryptogamic covers extend over vast polar tundra regions and their main components, e.g., bryophytes and lichens, are frequently the first visible colonizers of deglaciated areas. To understand their role in polar soil development, we analyzed how cryptogamic covers dominated by different bryophyte lineages (mosses and liverworts) influence the diversity and composition of edaphic bacterial and fungal communities as well as the abiotic attributes of underlying soils in the southern part of the Highlands of Iceland. For comparison, the same traits were examined in soils devoid of bryophyte covers. We measured an increase in soil C, N, and organic matter contents coupled with a lower pH in association with bryophyte cover establishment. However, liverwort covers showed noticeably higher C and N contents than moss covers. Significant changes in diversity and composition of bacterial and fungal communities were revealed between (a) bare and bryophyte-covered soils, (b) bryophyte covers and the underlying soils, and (c) moss and liverworts covers. These differences were more obvious for fungi than bacteria, and involved different lineages of saprotrophic and symbiotic fungi, which suggests a certain specificity of microbial taxa to particular bryophyte groups. In addition, differences observed in the spatial structure of the two bryophyte covers may be also responsible for the detected differences in microbial community diversity and composition. Altogether, our findings indicate that soil microbial communities and abiotic attributes are ultimately affected by the composition of the most conspicuous elements of cryptogamic covers in polar regions, which is of great value to predict the biotic responses of these ecosystems to future climate change.

Biodeterioration is a serious threat to the preservation of cultural heritage. Currently, the chemical treatments used to combat it must fulfil a series of restrictions to ensure that they are not harmful to humans or the environment. Borates satisfy these conditions but due to its high degree of leaching its application is limited to indoor areas. The use of electroprecipitation may to increase the range of applicability by allowing to precipitate, along the entire section of the stony materials, of a mixture of boron salts with different solubility (zinc, magnesium, and sodium borates) to cover a wide range of moisture conditions. The results obtained show that electroprecipitation not only increases the penetration depth of boron compounds but also allows the formation of compounds of different solubility, which allows the treatment to last over time. Furthermore, the treatment increased the mechanical properties and reduced the porosity of the stones treated, all without causing significant aesthetic changes.

Los líquenes son componentes esenciales de los ecosistemas terrestres antárticos, siendo capaces de salir victoriosos de la lucha contra las condiciones adversas reinantes en este continente. En las áreas libres de hielo de la Antártida marítima hay una gran diversidad de líquenes de gran tamaño y desarrollo, la cual va disminuyendo con la latitud. En estas áreas antárticas de condiciones más benévolas, los líquenes forman parte, junto con musgos, de una tundra frondosa que cubre los suelos y tapiza roquedos y promontorios rocosos. Sin embargo, en la Antártida Continental, donde las condiciones de baja temperatura, fuertes vientos y alta sequedad hacen difícil la vida, los líquenes son verdaderos héroes que resisten las condiciones tan extremas y se convierten en muchas zonas en la única forma de vida visible. En estas áreas desérticas, lo más sorprendente es que en áreas donde parece que no hay vida, los líquenes están presentes pero escondidos en fisuras y cavidades del interior de las piedras.

El 11 de febrero se celebró el Día Internacional de la Mujer y la Niña en la Ciencia. Con este motivo, el Departamento de Postgrado y Especialización del CSIC organizó esta iniciativa, a fin de ayudar a visibilizar a las mujeres investigadoras y promover el interés por la ciencia entre el alumnado de Educación Primaria y Secundaria; y para sensibilizar a jóvenes sobre el trabajo llevado a cabo por las mujeres del CSIC para la Ciencia. Women in Science (WINS) pretende sensibilizar a los y las más jóvenes del rol que tienen las mujeres en la ciencia a través de un avatar personalizado. La iniciativa propone un nuevo taller de cara al 11F de 2022 a los colegios a través de avatares personalizados.

[ES] Prasiola es un género de algas verdes foliosas perteneciente al filo Chlorophyta, que además constituye uno de los productores primarios más importantes de la Antártida en donde forma extensas cubiertas sobre el suelo de áreas con influencia marítima. Estas cubiertas criptogámicas, similares en estructura funcional a biocostras, tienen influencia en los atributos del suelo y en la diversidad bacteriana edáfica. Para conocer el papel que juega el establecimiento de estas cubiertas en la colonización de áreas deglacidas en este estudio se ha planteado la caracterización, por primera vez, de la estructura y diversidad taxonómica y funcional de las comunidades bacterianas y fúngicas de suelos con esta cubierta, mediante metabarcoding. Para ello se analizaron perfiles de suelo con cubierta dominada por Prasiola spp. y de suelo desnudo recogidos en la bahía de Punta Hannah (Isla Livingston, Península Antártica). Para comprobar la influencia del establecimiento de la cubierta sobre la biogeoquímica del suelo, se compararon los atributos edáficos de ambos tipos de suelo. Se realizó, además, un estudio filogenético de Prasiola utilizando las muestras de cubierta para observar el efecto que causan distintas especies en el suelo. Se han detectado diferencias estadísticamente significativas en la abundancia de filos de bacterias y sus funcionalidades ecosistémicas entre suelos con y sin cubierta. Sin embargo, las diferencias entre comunidades fúngicas son menores, ya que estas comunidades muestran una gran variabilidad, aunque también muestran ciertas tendencias que se pueden atribuir al distinto tipo de suelo. Se puede concluir que el establecimiento de cubiertas de Prasiola, además de condicionar los atributos abióticos del suelo, influye en la estructura de las comunidades microbianas edáficas y su funcionalidad., [EN] Prasiola is a genus of foliose green algae belonging to the phylum Chlorophyta. It is one of the most important primary producers in Antarctica where it forms broad covers in maritimeinfluenced areas. These cryptogamic covers, similar in functional structure to biocrusts, have an influence on soil attributes and soil bacterial diversity. In order to understand the role played by the establishment of these covers in colonisation of deglaciated areas, this study aims to characterise for the first time the taxonomic structure and functional diversity of bacterial and fungal communities inhabiting soils below this cover, using metabarcoding. For this purpose, profiles of soil with Prasiola spp. cover and bare soil collected from Hannah Point Bay (Livingston Island, Antarctic Peninsula), were analysed. To test the influence of cover establishment on soil biogeochemistry, soil attributes of both soil types were compared. In addition, a phylogenetic study of the Prasiola samples was carried out, in order to observe the effect that different species have on the soil. Statistically significant differences in the abundance of bacterial phyla and their ecosystem functionalities were detected between soils with and without cover. However, less differences were found between their fungal communities, which showed a high variability, although with certain trends that can be attributed to the different soil type. It can be concluded that the establishment of Prasiola covers, in addition to conditioning abiotic soil attributes, influences the structure of soil microbial communities and their functionality.

Cuando la lava de un volcán se enfría o por el retroceso glaciar quedan al descubierto suelos y rocas previamente cubiertas por hielo, los microorganismos son los primeros seres vivos que los colonizan. Esta colonización pionera es el paso previo e imprescindible para que se desarrollen otras formas de vida más complejas. Estas comunidades microbianas son las que se proponen estudiar en el proyecto ROCK-EATERS en el que participan Asunción de los Ríos y Fernando Garrido del Museo Nacional de Ciencias Naturales de Madrid (MNCN) y Javier Tamames del Centro Nacional de Biotecnología (CNB), ambos del CSIC. Los datos obtenidos les permitirán descubrir una diversidad antártica desconocida y caracterizar sus dinámicas para en el futuro poder valorar su resiliencia frente al cambio climático. El curso de la expedición se podrá seguir a través del blog Rock-eaters Antarctic Expedition: searching microbial life in rocks.

Throughout the Negev Desert highlands, thousands of ancient petroglyphs sites are susceptible to deterioration processes that may result in the loss of this unique rock art. Therefore, the overarching goal of the current study was to characterize the composition, diversity and effects of microbial colonization of the rocks to find ways of protecting these unique treasures. The spatial organization of the microbial colonizers and their relationships with the lithic substrate were analysed using scanning electron microscopy. This approach revealed extensive epilithic and endolithic colonization and close microbial–mineral interactions. Shotgun sequencing analysis revealed various taxa from the archaea, bacteria and some eukaryotes. Metagenomic coding sequences (CDS) of these microbial lithobionts exhibited specific metabolic pathways involved in the rock elements' cycles and uptake processes. Thus, our results provide evidence for the potential participation of the microorganisms colonizing these rocks during different solubilization and mineralization processes. These damaging actions may contribute to the deterioration of this extraordinary rock art and thus threaten this valuable heritage. Shotgun metagenomic sequencing, in conjunction with the in situ scanning electron microscopy study, can thus be considered an effective strategy to understand the complexity of the weathering processes occurring at petroglyph sites and other cultural heritage assets.

The ventral surfaces of translucent rocks from hot desert pavements often harbor hypolithic microbial communities, which are mostly dominated by cyanobacteria. The Namib Desert fog belt supports extensive hypolithic colonization of quartz rocks, which are also colonized by lichens on their dorsal surfaces. Here, we aim to evaluate whether lichens colonize the ventral surface of the rocks (i.e., show hypolithic lifestyle) and compare the bacterial composition of these coastal hypolithic communities with those found inland. Fungal DNA barcoding and fungal and bacterial Illumina metabarcoding were combined with electron microscopy to characterize the composition and spatial structure of hypolithic communities from two (coastal and inland) areas in the Namib Desert. We report, for the first time, the structure and composition of lichen-dominated hypolithic communities found in the coastal zone of the Namib Desert with extensive epilithic lichen cover. Lichen modified areoles with inverted morphology of the genus Stellarangia (three lineages) and Buellia (two lineages) were the main components of these hypolithic communities. Some of these lineages were also found in epilithic habitats. These lichen-dominated hypolithic communities differed in structural organization and bacterial community composition from those found in inland areas. The hypolithic lichen colonization characterized here seems not to be an extension of epilithic or biological soil crust lichen growths but the result of specific sublithic microenvironmental conditions. Moisture derived from fog and dew could be the main driver of this unique colonization.

Cuando, por efecto del cambio climático, retroceden los glaciares, se produce la colonización de suelos y rocas que habían permanecido cubiertos por una densa capa de hielo durante largos periodos de tiempo. Estos procesos de colonización responden a procesos de sucesión primaria en que los microorganismos son los primeros colonizadores tras la retirada del hielo. La actividad de estos microorganismos pioneros en regiones polares es fundamental para el posterior establecimiento de comunidades más complejas que inducen en la zona característicos incrementos de cobertura vegetal. Es también muy importante el papel de los microorganismos que colonizan las rocas, ya que a través de las interacciones microorganismo-mineral establecidas se generan nutrientes esenciales para el establecimiento de distintas formas de vida en áreas deglaciadas. La composición y diversidad de estas comunidades microbianas litobiónticas difiere drásticamente de las presentes en los suelos. La contribución de los microorganismos a la colonización de áreas deglaciadas polares no se limita a las etapas iniciales de la sucesión, sino que hay un reemplazo de taxones microbianos que favorece el desarrollo de distintas funciones a lo largo de la cronosecuencias establecidas. De hecho, los primeros signos visibles de la colonización son la aparición de cubiertas criptogámicas, estructuras biosedimentarias formadas por líquenes y musgos, las cuales contienen comunidades microbianas muy diversas que favorecen el reciclado de nutrientes y el desarrollo del suelo. Asimismo, a medida que la sucesión avanza y se forman comunidades microbianas más estables y estructuradas en las rocas, su contribución a la sucesión es mas significativa.

We still lack studies that provide evidence for direct links between the development of soil surface cryptogamic communities and soil attributes and functioning. This is particularly true in areas free of potentially confounding factors such as different soil types, land uses, or anthropogenic disturbances. Despite the ecological importance of polar ecosystems and their sensitivity to climate change, we are far from understanding how their soils function and will respond to climate change-driven alterations in above- and belowground features., We used two complementary approaches (i.e. cover gradients in the forefront of retreating glaciers as well as long-time deglaciated areas with well-developed cryptogamic cover types) to evaluate the role of cryptogams driving multiple soil biotic and abiotic attributes and functioning rates in polar terrestrial ecosystems., Increases in cryptogamic cover were consistently related to increases in organic matter accumulation, soil fertility, and bacterial diversity, but also in enhanced soil functioning rates in both sampling areas. However, we also show that the ability to influence soil attributes varies among different polar cryptogamic covers, indicating that their differential ability to thrive under climate-change scenarios will largely determine the fate of polar soils in coming decades.

Soils can influence climate by sequestering or emitting greenhouse gases (GHG) such as carbon dioxide (CO2),methane (CH4), and nitrous oxide (N2O). We are far from understanding the direct influence of cryptogamiccovers on soil GHGfluxes, particularly in areas free of potential anthropogenic confounding factors.We assessed the role of well-developed cryptogamic covers in soil attributes, as well as in the in-situ exchange ofGHG between Antarctic soils and the atmosphere during the austral summer. We found lower values of soil or-ganic matter, total organic carbon, and total nitrogen in bare areas than in soils covered by mosses and, particu-larly, lichens. These differences, together with concomitant decreases and increases in soil temperature andmoisture, respectively, resulted in increases in in-situ CO2emission (i.e. ecosystem respiration) and decreasesin CH4uptake but no significant changes in N2Ofluxes. We found consistent linear positive and negative relation-ships between soil attributes (i.e. soil organic matter, total organic carbon and total nitrogen) and CO2emissionsand CH4uptake, respectively, and polynomial relationships between these soil attributes and net N2Ofluxes.Our results indicate that any increase in the area occupied by cryptogams in terrestrial Antarctic ecosystems (dueto increased growing season and increasingly warming conditions) will likely result in parallel increases in soilfertility as well as in an enhanced capacity to emit CO2and a decreased capacity to uptake CH4.Suchchanges,un-less offset by parallel C uptake processes, would represent a paradigmatic example of a positive climate changefeedback. Further, we show that the fate of these terrestrial ecosystems under future climate scenarios, as wellas their capacity to exchange GHG with the atmosphere might depend on the relative ability of different above-ground cryptogams to thrive under the new conditions.

Polar glacier forefields offer an unprecedented framework for studying community assembly processes in regions that aregeographically and climatically isolated. Through amplicon sequence variant (ASV) inference, we compared thecomposition and structure of soil bacterial communities from glacier forefields in Iceland and Antarctica to assess overlapbetween communities and the impact of established cryptogamic covers on the uniqueness of their taxa. These pioneermicrobial communities were found to share only 8% of ASVs and each taxonomic group’s contribution to the shared ASVdata subset was heterogeneous and independent of their relative abundance. Although the presence of ASVs specific to oneglacier forefield and/or different cryptogam cover values confirms the existence of habitat specialist bacteria, our data showthat the influence of cryptogams on the edaphic bacterial community structure also varied also depending on thetaxonomic group. Hence, the establishment of distinct cryptogamic covers is probably not the only factor driving theuniqueness of bacterial communities at both poles. The structure of bacterial communities colonising deglaciated areasseems also conditioned by lineage-specific limitations in their dispersal capacity and/or their establishment andpersistence in these isolated and hostile regions.

Microbial communities found in arid environments are commonly represented by biologicalsoil crusts (BSCs) and endolithic assemblages. There is still limited knowledge concerning endolithsand BSCs occurring in the cold mountain desert of Pamir. The aim of the study was to investigate thecomposition and structure of endolithic bacterial communities in comparison to surrounding BSCs inthree subregions of the Eastern Pamir (Tajikistan). The endolithic and BSC communities were studiedusing culture-independent and culture dependent techniques. The structure of the endolithic bacte-rial communities can be characterized as Actinobacteria–Proteobacteria–Bacteroidetes–Chloroflexi–Cyanobacteria, while the BSCs’ can be described as Proteobacteria–Actinobacteria–Bacteroidetes–Cyanobacteria assemblages with low representation of other bacteria. The endolithic cyanobacterialcommunities were characterized by the high percentage of Chroococcidiopsaceae, Nodosilineaceae,Nostocaceae and Thermosynechococcaceae, while in the BSCs were dominated by Nodosilineaceae,Phormidiaceae and Nostocaceae. The analysis of 16S rRNA genes of the cyanobacterial culturesrevealed the presence of possibly novel species of Chroococcidiopsis,Gloeocapsopsis and Wilmottia.Despite the niches’ specificity, which is related to the influence of microenvironment factors onthe composition and structure of endolithic communities, our results illustrate the interrelationbetween the endoliths and the surrounding BSCs in some regions. The structure of cyanobacterialcommunities from BSC was the only one to demonstrate some subregional differences.

In an era of rapid climate change and expansion of desertification, the extremely harsh conditions of drylands are a true challenge for microbial life. Under drought conditions, where most life forms cannot survive, rocks represent the main refuge for life. Indeed, the endolithic habitat provides thermal buffering, physical stability, and protection against incident ultraviolet (UV) radiation and solar radiation and, to some extent, ensures water retention to microorganisms. The study of these highly specialized extreme-tolerant and extremophiles may provide tools for understanding micro-bial interactions and processes that allow them to keep their metabolic machinery active under conditions of dryness and oligotrophy that are typically incompatible with active life, up to the dry limits for life. Despite lithobiontic communities being studied all over the world, a comprehensive understanding of their ecology, evolution, and adaptation is still nascent. Herein, we survey the fungal component of these microbial ecosystems. We first provide an overview of the main defined groups (i.e., lichen-forming fungi, black fungi, and yeasts) of the most known and studied Antarctic endolithic communities that are almost the only life forms ensuring ecosystem functionality in the ice-free areas of the continent. For each group, we discuss their main traits and their diversity. Then, we focus on the fungal taxonomy and ecology of other worldwide endolithic communities. Finally, we highlight the utmost importance of a global rock survey in order to have a comprehensive view of the diversity, distribution, and functionality of these fungi in drylands, to obtain tools in desert area management, and as early alarm systems to climate change.

Widespread geographic distributions in lichens have been usually explained by the high dispersal capacity of their tiny diaspores. However, recent phylogenetic surveys have challenged this assumption and provided compelling evidence for cryptic speciation and more restricted distribution ranges in diverse lineages of lichen-forming fungi. To evaluate these scenarios, we focus on the fungal genus Pseudephebe (Parmeliaceae) which includes amphitropical species, a distribution pattern whose origin has been a matter of debate since first recognized in the nineteenth century. In our study, a six-locus dataset and a broad specimen sampling covering almost all Earth's continents is used to investigate species delimitation in Pseudephebe. Population structure, gene flow and dating analyses, as well as genealogical reconstruction methods, are employed to disentangle the most plausible transcontinental migration routes, and estimate the timing of the origin of the amphitropical distribution and the Antarctic populations. Our results demonstrate the existence of three partly admixed phylogenetic species that diverged between the Miocene and Pliocene, and whose Quaternary distribution has been strongly driven by glacial cycles. Pseudephebe minuscula is the only species showing an amphitropical distribution, with populations in Antarctica, whereas the restricted distribution of P. pubescens and an undescribed Alaskan species might reflect the survival of these species in European and North American refugia. Our microevolutionary analyses suggest a Northern Hemisphere origin for P. minuscula, which could have dispersed into the Southern Hemisphere directly and/or through “mountain-hopping” during the Pleistocene. The Antarctic populations of this species are sorted into two genetic clusters: populations of the Antarctic Peninsula were grouped together with South American ones, and the Antarctic Continental populations formed a second cluster with Bolivian and Svalbard populations