Contributions of in situ microscopy to the current understanding of stone biodeterioration

In situ microscopy consists of simultaneously applying several microscopy techniques without separating the biological component from its habitat. Over the past few years, this strategy has allowed characterization of the biofilms involved in biodeterioration processes affecting stone monuments and has revealed the biogeophysical and biogeochemical impact of the microbiota present. In addition, through in situ microscopy diagnosis, appropriate treatments can be designed to resolve the problems related to microbial colonization of stone monuments. [Int Microbiol 2005; 8(3):181-188

Study of lichens with different state of hydration by the combination of low temperature scanning electron and confocal laser scanning microscopies

The use of techniques such as low temperature scanning electron microscopy (LTSEM) and confocal laser scanning microscopy (CLSM) allows the study of lichen thalli in different states of hydration and also near the natural state. The spatial organization of desiccated thalli, with reduced, very compact algal layers, is different from that of hydrated ones. Sometimes, the observation with transmission electron microscopy (TEM) of photobiont pyrenoids from desiccated thalli reports pyrenoids with a central part of a weak stained matrix lacking pyrenoglobuli, named “empty zones”. “Empty zones” are not distinguishable with LTSEM and do not present immunolabelling with rubisco antibody in TEM. These zones could be originated by an expansion process during rehydration produced in chemical fixation

The spatial structures of hypolithic communities in the Dry Valleys of East Antarctica

Received: 27 May 2014 / Revised: 19 August 2014 / Accepted: 21 August 2014 / Published online: 31 August 2014Hypolithic communities represent important reservoirs of microbial life in hyper-arid deserts. A number of studies on the diversity and ecology of these communities from different geographic areas have been reported in the past decade, but the spatial distribution of the different components of these communities is still not understood. Moss- and cyanobacteria-dominated hypolithic community morphotypes from Miers Valley (McMurdo Dry Valleys, East Antarctica) were analyzed by electron microscopy in order to characterize the microscale spatial structure. The two communities showed a high degree of internal organization, but differing according to the biological composition. In moss-dominated hypoliths, the moss plantlets are intermixed with mineral fragments of soil origin. However, in cyanobacteria-dominated hypoliths, a layered spatial organization was structured by filamentous cyanobacteria and associated extracellular polymeric components. While moss cells were lacking in cyanobacteria-dominated communities, biofilms formed by cyanobacteria and heterotrophic bacteria were observed in both community morphotypes. The water-holding capacity of both live and dead moss cells and the associated organic matrix, together with the protective properties of the extracellular polymeric substances, could facilitate the survival and activity of these communities. Similar structural strategies can favor the survival of microbial communities in different extreme environments.The microscopy study was funded by the Spanish Education Ministry grant CTM2012- 38222-C02-02.Peer reviewe

Microorganisms in desert rocks: the edge of life on Earth

This article reviews current knowledge on microbial communities inhabiting endolithic habitats in the arid and hyper-arid regions of our planet. In these extremely dry environments, the most common survival strategy is to colonize the interiors of rocks. This habitat provides thermal buffering, physical stability, and protection against incident UV radiation, excessive photosynthetically active radiation, and freeze-thaw events. Above all, through water retention in the rocks' network of pores and fi ssures, moisture is made available. Some authors have argued that dry environments pose the most extreme set of conditions faced by microorganisms. Microbial cells need to withstand the biochemical stresses created by the lack of water, along with temperature fl uctuations and/or high salinity. In this review, we also address the variety of ways in which microorganismsdeal with the lack of moisture in hyper-arid environments and point out the diversity of microorganisms that are able to cope with only the scarcest presence of water. Finally, we discuss the important clues to the history of life on Earth, and perhaps other places in our solar system, that have emerged from the study of extreme microbial ecosystems. [Int Microbiol (2012); 15(4):171-181

Microorganisms in desert rocks: the edge of life on Earth

This article reviews current knowledge on microbial communities inhabiting endolithic habitats in the arid and hyper-arid regions of our planet. In these extremely dry environments, the most common survival strategy is to colonize the interiors of rocks. This habitat provides thermal buffering, physical stability, and protection against incident UV radiation, excessive photosynthetically active radiation, and freeze-thaw events. Above all, through water retention in the rocks' network of pores and fi ssures, moisture is made available. Some authors have argued that dry environments pose the most extreme set of conditions faced by microorganisms. Microbial cells need to withstand the biochemical stresses created by the lack of water, along with temperature fl uctuations and/or high salinity. In this review, we also address the variety of ways in which microorganismsdeal with the lack of moisture in hyper-arid environments and point out the diversity of microorganisms that are able to cope with only the scarcest presence of water. Finally, we discuss the important clues to the history of life on Earth, and perhaps other places in our solar system, that have emerged from the study of extreme microbial ecosystems. [Int Microbiol (2012); 15(4):171-181

Exposición en el Museo Nacional de Ciencias Naturales. Microbiología: explorando más allá de lo visible

Esta exposición sobre microbiología que se puede visitar en el Museo Nacional de Ciencias Naturales del 9 de Septiembre a 8 de Diciembre de 2021, es el resultado de la colaboración entre la Sociedad Española de Microbiología (SEM) y el Museo Nacional de Ciencias Naturales (MNCN-CSIC), en el año del 75 aniversario de esta Sociedad (1946-2021) (Fig. 1). El objetivo principal de esta exposición es poner de manifiesto la importancia de los microorganismos en nuestras vidas, sus Exposición en el Museo Nacional de Ciencias Naturales. Microbiología: explorando más allá de lo visible ASUNCIÓN DE LOS RÍOS MURILLO Museo Nacional de Ciencias Naturales - CSIC [email protected] Figura 1. Aspecto general de la sección introductoria de la exposición. Autor de la imagen: Jose Mª Cazcarra. numerosos efectos beneficiosos y la gran variedad de aplicaciones que pueden tener en diferentes campos como la biotecnología, la protección del medioambiente o la medicina

A molecular reappraisal of Abrothallus species growing on lichens of the order Peltigerales

© 2015 Magnolia Press. Species of the genus Abrothallus (Abrothallales, Dothideomycetes) are obligately lichenicolous (lichen-inhabiting) and grow on a wide variety of foliose and fruticose lichens. Bayesian Interference (BI) and Maximum Likelihood (ML) analyses of two gene loci—rDNA ITS and TEF-α—were used in order to infer the phylogenetic relationships among lineages of Abrothallus associated with hosts from the order Peltigerales (Lecanoromycetes). We found that the clade is subdivided into 13 lineages each of which can be delimited also by phenotypic criteria. Seven new species (Abrothallus boomii, A. canariensis, A. doliiformis, A. eriodermae, A. ertzii, A. etayoi and A. nephromatis) are described, two of which are known only by their asexual stage. Abrothallus welwitschii is lectotypified, and the original description is complemented. Vouauxiomyces brattii and Epinephroma kamchatica are combined within Abrothallus.Peer Reviewe

Ecology of endolithic lichens colonizing granite in continental Antarctica

In this study, the symbiont cells of several endolithic lichens colonizing granite in continental Antarctica and the relationships they have with the abiotic environment were analyzed in situ, in order to characterize the microecosystems integrating these lichens, from a microecological perspective. Mycobiont and photobiont cells, the majority classified as living by fluorescent vitality testing, were observed distributed through the fissures of the granite. The fact that extracellular polymeric substances were commonly observed close to these cells and the features of these compounds, suggest a certain protective role for these substances against the harsh environmental conditions. Different chemical, physical and biological relationships take place within the endolithic biofilms where the lichens are found, possibly affecting the survival and distribution of these organisms. The alteration of bedrock minerals and synthesis of biominerals in the proximity of these lichens give rise to different chemical microenvironments and suggest their participation in mineral nutrient cycling