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

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

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

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

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

Ecosystem function decays by fungal outbreaks in Antarctic microbial mats

Antarctica harbours a remarkably diverse range of freshwater bodies and terrestrial ecosystems, where microbial mats are considered the most important systems in terms of biomass and metabolic capabilities. We describe the presence of lysis plaque-like macroscopic blighted patches within the predominant microbial mats on Livingston Island (Antarctic Peninsula). Those blighting circles are associated with decay in physiological traits as well as nitrogen depletion and changes in the spatial microstructure; these alterations were likely related to disruption of the biogeochemical gradients within the microbial ecosystem caused by an unusually high fungal abundance and consequent physical alterations. This phenomenon has been evidenced at a time of unprecedented rates of local warming in the Antarctic Peninsula area, and decay of these ecosystems is potentially stimulated by warmer temperaturesWe thank the LIMNOPOLAR team members for their assistance in collecting samples and the UTM and Las Palmas Navy crew for logistical support. We are grateful to Warwick F. Vincent for comments that improved the final manuscript. This study was supported by grants CGL2005–06549-CO2-1, POL2006–06635 and CTM2011– 28736 to A.Q. CTM2008–05134-E/ANT and CTM2009–08644-E to A.A., and CTM2012–38222-C02–02 to A.dR. D.V. was supported by the Spanish Ministry of Science and Innovation grant BES-2006–14027, A.LB. by the Ramón y Cajal contract RYC-2010–06300, and D.AdC. by the Marie Curie IIF grant PIIF-GA-2012-328287. In memoriam: We are grateful to Fernando Pinto for technical assistance with LTSE