Astrobiological field campaign to a volcanosedimentary mars analogue methane producing subsurface protected ecosystem: Imuruk Lake (Alaska)

Viking missions reported adverse conditions for life in Mars surface. High hydrogen signal obtained by Mars orbiters has increased the interest in subsurface prospection as putative protected Mars environment with life potential. Permafrost has attracted considerable interest from an astrobiological point of view due to the recently reported results from the Mars exploration rovers. Considerable studies have been developed on extreme ecosystems and permafrost in particular, to evaluate the possibility of life on Mars and to test specific automated life detection instruments for space missions. The biodiversity of permafrost located on the Bering Land Bridge National Preserve has been studied as an example of subsurface protected niche of astrobiological interest. Different conventional (enrichment and isolation) and molecular ecology techniques (cloning, fluorescence "in situ" probe hybridization, FISH) have been used for isolation and bacterial identificationThe expedition to Imuruk Lake was supported by Centro de Astrobiología-INTA (Spain). The laboratory experimental procedures were supported by Grant AYA 2010–20213 “Desarrollo de Tecnología para la identificación de vida de forma automática” from the Spanish Governmen

Astrobiological field campaign to a volcanosedimentary mars analogue methane producing subsurface protected ecosystem: Imuruk Lake (Alaska)

Viking missions reported adverse conditions for life in Mars surface. High hydrogen signal obtained by Mars orbiters has increased the interest in subsurface prospection as putative protected Mars environment with life potential. Permafrost has attracted considerable interest from an astrobiological point of view due to the recently reported results from the Mars exploration rovers. Considerable studies have been developed on extreme ecosystems and permafrost in particular, to evaluate the possibility of life on Mars and to test specific automated life detection instruments for space missions. The biodiversity of permafrost located on the Bering Land Bridge National Preserve has been studied as an example of subsurface protected niche of astrobiological interest. Different conventional (enrichment and isolation) and molecular ecology techniques (cloning, fluorescence >in situ> probe hybridization, FISH) have been used for isolation and bacterial identification.The expedition to Imuruk Lake was supported by Centro de Astrobiologia-INTA (Spain). The laboratory experimental procedures were supported by Grant AYA 2010–2013 “Desarrollo de Tecnología para la identificación de vida de forma automática” from the Spanish Government.Peer Reviewe

Constraining the preservation of organic compounds in Mars analog nontronites after exposure to acid and alkaline fluids

The presence of organic matter in lacustrine mudstone sediments at Gale crater was revealed by the Mars Science Laboratory Curiosity rover, which also identified smectite clay minerals. Analogue experiments on phyllosilicates formed under low temperature aqueous conditons have illustrated that these are excellent reservoirs to host organic compounds against the harsh surface conditions of Mars. Here, we evaluate whether the capacity of smectites to preserve organic compounds can be influenced by a short exposure to different diagenetic fluids. We analyzed the stability of glycine embedded within nontronite samples previously exposed to either acidic or alkaline fluids (hereafter referred to as “treated nontronites”) under Mars-like surface conditions. Analyses performed using multiple techniques showed higher photodegradation of glycine in the acid-treated nontronite, triggered by decarboxylation and deamination processes. In constrast, our experiments showed that glycine molecules were preferably incorporated by ion exchange in the interlayer region of the alkali-treated nontronite, conferring them a better protection against the external conditions. Our results demonstrate that smectite previously exposed to fluids with different pH values influences how glycine is adsorbed into their interlayer regions, affecting their potential for preservation of organic compounds under contemporary Mars surface conditionsEuropean Commission | Ref. FP7 n. 307496European Commission | Ref. H2020 n. 818602Ministerio de Economía | Ref. MDM-2017-0737Ministerio de Economía | Ref. ESP2017-89053-C2-1-

Biomarker Profiling of Microbial Mats in the Geothermal Band of Cerro Caliente, Deception Island (Antarctica): Life at the Edge of Heat and Cold

© María Ángeles Lezcano et al. 2019.Substrate–atmosphere interfaces in Antarctic geothermal environments are hot–cold regions that constitute thin habitable niches for microorganisms with possible counterparts in ancient Mars. Cerro Caliente hill in Deception Island (active volcano in the South Shetland Islands) is affected by ascending hydrothermal fluids that form a band of warm substrates buffered by low air temperatures. We investigated the influence of temperature on the community structure and metabolism of three microbial mats collected along the geothermal band of Cerro Caliente registering 88°C, 8°C, and 2°C at the time of collection. High-throughput sequencing of small subunit ribosomal ribonucleic acid (SSU rRNA) genes and Life Detector Chip (LDChip) microarray immunoassays revealed different bacterial, archaeal, and eukaryotic composition in the three mats. The mat at 88°C showed the less diverse microbial community and a higher proportion of thermophiles (e.g., Thermales). In contrast, microbial communities in the mats at 2°C and 8°C showed relatively higher diversity and higher proportion of psychrophiles (e.g., Flavobacteriales). Despite this overall association, similar microbial structures at the phylum level (particularly the presence of Cyanobacteria) and certain hot- and cold-tolerant microorganisms were identified in the three mats. Daily thermal oscillations recorded in the substrate over the year (4.5–76°C) may explain the coexistence of microbial fingerprints with different thermal tolerances. Stable isotope composition also revealed metabolic differences among the microbial mats. Carbon isotopic ratios suggested the Calvin–Benson–Bassham cycle as the major pathway for carbon dioxide fixation in the mats at 2°C and 8°C, and the reductive tricarboxylic acid cycle and/or the 3-hydroxypropionate bicycle for the mat at 88°C, indicating different metabolisms as a function of the prevailing temperature of each mat. The comprehensive biomarker profile on the three microbial mats from Cerro Caliente contributes to unravel the diversity, composition, and metabolism in geothermal polar sites and highlights the relevance of geothermal-cold environments to create habitable niches with interest in other planetary environments.This study has been funded by the Spanish Research Agency (AEI) from the Ministry of Science Innovation and Universities and the European FEDER Grants Nos. ESP2015-69540-R, RYC2014-19446, and CGL2015-74254-JIN; the AEI Project No. MDM-2017-0737 Unidad de Excelencia ‘‘Marı´a de Maeztu,’’ and the European Research Council Starting Grant (ERC StG) No. 307496. M.A´ . Lezcano and M.A´ . Fernández Martínez were supported by a postdoctoral fellowship by the Youth Employment Initiative from the European Union and implanted in Comunidad de Madrid

Fractal properties of isolines at varying altitude reveal different dominant geological processes on Earth

Geometrical properties of landscapes result from the geological processes that have acted through time. The quantitative analysis of natural relief represents an objective form of aiding in the visual interpretation of landscapes, as studies on coastlines, river networks, and global topography, have shown. Still, an open question is whether a clear relationship between the quantitative properties of landscapes and the dominant geomorphologic processes that originate them can be established. In this contribution, we show that the geometry of topographic isolines is an appropriate observable to help disentangle such a relationship. A fractal analysis of terrestrial isolines yields a clear identification of trenches and abyssal plains, differentiates oceanic ridges from continental slopes and platforms, localizes coastlines and river systems, and isolates areas at high elevation (or latitude) subjected to the erosive action of ice. The study of the geometrical properties of the lunar landscape supports the existence of a correspondence between principal geomorphic processes and landforms. Our analysis can be easily applied to other planetary bodies.Comment: 21 pages, 7 figure

Geomicrobiological heterogeneity of lithic habitats in the extreme environment of Antarctic nunataks: a potential early Mars analog

Nunataks are permanent ice-free rocky peaks that project above ice caps in polar regions, thus being exposed to extreme climatic conditions throughout the year. They undergo extremely low temperatures and scarcity of liquid water in winter, while receiving high incident and reflected (albedo) UVA-B radiation in summer. Here, we investigate the geomicrobiology of the permanently exposed lithic substrates of nunataks from Livingston Island (South Shetlands, Antarctic Peninsula), with focus on prokaryotic community structure and their main metabolic traits. Contrarily to first hypothesis, an extensive sampling based on different gradients and multianalytical approaches demonstrated significant differences for most geomicrobiological parameters between the bedrock, soil, and loose rock substrates, which overlapped any other regional variation. Brevibacillus genus dominated on bedrock and soil substrates, while loose rocks contained a diverse microbial community, including Actinobacteria, Alphaproteobacteria and abundant Cyanobacteria inhabiting the milder and diverse microhabitats within. Archaea, a domain never described before in similar Antarctic environments, were also consistently found in the three substrates, but being more abundant and potentially more active in soils. Stable isotopic ratios of total carbon (δ 13C) and nitrogen (δ 15N), soluble anions concentrations, and the detection of proteins involved in key metabolisms via the Life Detector Chip (LDChip), suggest that microbial primary production has a pivotal role in nutrient cycling at these exposed areas with limited deposition of nutrients. Detection of stress-resistance proteins, such as molecular chaperons, suggests microbial molecular adaptation mechanisms to cope with these harsh conditions. Since early Mars may have encompassed analogous environmental conditions as the ones found in these Antarctic nunataks, our study also contributes to the understanding of the metabolic features and biomarker profiles of a potential Martian microbiota, as well as the use of LDChip in future life detection missions.This project has been funded by the Spanish Ministry of Science and Innovation (MICINN)/European Regional Development Fund (FEDER) project no. RTI2018-094368-B-I00; the European Research Council Consolidator grant no. 818602; and the Spanish State Research Agency (AEI) project no. MDM-2017-0737, Unidad de Excelencia “María de Maeztu” to Centro de Astrobiología

The Raman laser spectrometer ExoMars simulator (RLS Sim): A heavy‐duty Raman tool for ground testing on ExoMars

Producción CientíficaThe Raman laser spectrometer (RLS) instrument onboard the Rosalind Franklin rover of the ExoMars 2022 mission will analyze powdered samples on Mars to search for traces of life. To prepare for the mission, the RLS scientific team has developed the RLS ExoMars Simulator (RLS Sim), a flexible model of RLS that operates similarly to the actual instrument, both in laboratory and field conditions, while also emulating the rover operational constraints in terms of sample distribution that are relevant to the Raman analysis. This system can operate autonomously to perform RLS-representative analysis in one or several samples, making it very useful to perform heavy experimental tasks that would otherwise be impossible using a flight-representative model of the instrument. In this work, we introduce the current configuration of the RLS Sim that has incorporated new hardware elements such as the RAman Demonstrator 1 (RAD1) spectrometer with the objective of approaching its performance to that of the actual RLS instrument. To evaluate the scientific capability of the RLS Sim, we have compared it with a replica model of RLS, the RLS Flight Spare (FS). Several acquisition aspects have been evaluated based on the analysis of select samples, assessing the performance in terms of spectral range and resolution and also studying several issues related to the evolution of signal-to-noise ratio (SNR) with different acquisition parameters, especially the number of accumulations. This performance analysis has shown that the RLS Sim in its updated configuration will be a key model to perform support science for the ExoMars mission and the RLS instrument on the Rosalind Franklin rover. Designed to work intensively, the use of the RLS Sim in combination with the RLS FS will facilitate maximizing the scientific return of the RLS spectrometer during Martian operations.Secretaría de Estado de Investigación, Desarrollo e Innovación (grant PID2019-107442RBC31)European Union’s Horizon 2020 research and innovation program (grant 687302

Coupled C, H, N, S and Fe biogeochemical cycles operating in the continental deep subsurface of the Iberian Pyrite Belt

Microbial activity is a major contributor to the biogeochemical cycles that make up the life support system of planet Earth. A 613 m deep geomicrobiological perforation and a systematic multi-analytical characterization revealed an unexpected diversity associated with the rock matrix microbiome that operates in the subsurface of the Iberian Pyrite Belt (IPB). Members of 1 class and 16 genera were deemed the most representative microorganisms of the IPB deep subsurface and selected for a deeper analysis. The use of fluorescence in situ hybridization allowed not only the identification of microorganisms but also the detection of novel activities in the subsurface such as anaerobic ammonium oxidation (ANAMMOX) and anaerobic methane oxidation, the co-occurrence of microorganisms able to maintain complementary metabolic activities and the existence of biofilms. The use of enrichment cultures sensed the presence of five different complementary metabolic activities along the length of the borehole and isolated 29 bacterial species. Genomic analysis of nine isolates identified the genes involved in the complete operation of the light-independent coupled C, H, N, S and Fe biogeochemical cycles. This study revealed the importance of nitrate reduction microorganisms in the oxidation of iron in the anoxic conditions existing in the subsurface of the IPBFP7 Ideas: European Research Council, Grant/Award Number: ERC Advanced Grant #250-35