Sun exposure drives Antarctic cryptoendolithic community structure and composition

AbstractThe harsh environmental conditions of the ice-free regions of Continental Antarctica are considered one of the closest Martian analogues on Earth. There, rocks play a pivotal role as substratum for life and endolithism represents a primary habitat for microorganisms when external environmental conditions become incompatible with active life on rock surfaces. Due to the thermal inertia of rock, the internal airspace of lithic substratum is where microbiota find a protected and buffered microenvironment, allowing life to spread throughout these regions with extreme temperatures and low water availability. The high degree of adaptation and specialization of the endolithic communities makes them highly resistant but scarsely resilient to any external perturbation and thus, any shifts in microbial community composition may serve as early-alarm systems of environmental perturbation, including climate change.Previous research concluded that altitude and distance from sea do not play as driving factors in shaping microbial abundance and diversity, while sun exposure was hypothesized as significant parameter influencing endolithic settlement and development. This study aims to explore our hypothesis that changes in sun exposure translate to shifts in community composition and abundances of main biological compartments (fungi, algae and bacteria) in the Antarctic cryptoendolithic communities. We performed a preliminary molecular survey, based on DGGE and qPCR tecniques, of 48 rocks with varying sun exposure, collected in Victoria Land along an altitudinal transect from 834 to 3100 m a.s.l.Our findings demonstrate that differences in sun radiation between north and south exposure influence temperature of rocks surface, availability of water and metabolic activity and also have significant impact on community composition and microbial abundance

Draft Genome Sequence of the Yeast Rhodotorula sp. Strain CCFEE 5036, Isolated from McMurdo Dry Valleys, Antarctica.

A draft genome sequence was assembled and annotated of the basidiomycetous yeast Rhodotorula sp. strain CCFEE 5036, isolated from Antarctic soil communities. The genome assembly is 19.07 megabases and encodes 6,434 protein-coding genes. The sequence will contribute to understanding the diversity of fungi inhabiting polar regions

Metagenomes in the Borderline Ecosystems of the Antarctic Cryptoendolithic Communities.

Antarctic cryptoendolithic communities are microbial ecosystems dwelling inside rocks of the Antarctic desert. We present the first 18 shotgun metagenomes from these communities to further characterize their composition, biodiversity, functionality, and adaptation. Future studies will integrate taxonomic and functional annotations to examine the pathways necessary for life to evolve in the extremes

Integrity of the DNA and Cellular Ultrastructure of Cryptoendolithic Fungi in Space or Mars Conditions: A 1.5-Year Study at the International Space Station

The black fungi Cryomyces antarcticus and Cryomyces minteri are highly melanized and are resilient to cold, ultra-violet, ionizing radiation and other extreme conditions. These microorganisms were isolated from cryptoendolithic microbial communities in the McMurdo Dry Valleys (Antarctica) and studied in Low Earth Orbit (LEO), using the EXPOSE-E facility on the International Space Station (ISS). Previously, it was demonstrated that C. antarcticus and C. minteri survive the hostile conditions of space (vacuum, temperature fluctuations, and the full spectrum of extraterrestrial solar electromagnetic radiation), as well as Mars conditions that were simulated in space for a 1.5-year period. Here, we qualitatively and quantitatively characterize damage to DNA and cellular ultrastructure in desiccated cells of these two species, within the frame of the same experiment. The DNA and cells of C. antarcticus exhibited a higher resistance than those of C. minteri. This is presumably attributable to the thicker (melanized) cell wall of the former. Generally, DNA was readily detected (by PCR) regardless of exposure conditions or fungal species, but the C. minteri DNA had been more-extensively mutated. We discuss the implications for using DNA, when properly shielded, as a biosignature of recently extinct or extant life

Humidity and low pH boost occurrence of Onygenales fungi in soil at global scale

Soils are important reservoirs for potential human pathogens and opportunistic fungi such as the dermatophyte or dimorphic fungi in the order Onygenales. In soils, these taxa are decomposers but many of them have the potential to cause respiratory and skin diseases in humans and, in some cases, systemic infections. Even so, the factors that determine the biogeography and ecology of order Onygenales remain largely undocumented. To address this knowledge gap, we surveyed members of Onygenales from topsoil fungal communities at 235 sites across six continents and provided a first global atlas. We retrieved 4.3% of the total fungal sequences (∼420 Onygenales) across nine biomes ranging from deserts to tropical forests. This work advances our knowledge on the ecology and global distribution of order Onygenales and suggests the hypothesis that wet and acid soils support the larger proportions of these fungi, while their richness is constrained by aridity.C.C. and L.S. wish to thank the Italian National Program for Antarctic Research (PNRA) for supporting their research. M.D-B. is supported by a project from the Spanish Ministry of Science and Innovation (PID2020-115813RA-I00), and a project PAIDI 2020 from the Junta de Andalucía (P20_00879). Microbial distribution and colonization research in B.K.S. lab is funded by Australian Research Council (DP190103714). E.G. is supported by the European Research Council grant agreement 647038 (BIODESERT)

Geology and elevation shape bacterial assembly in Antarctic endolithic communities

Ice free areas of continental Antarctica are among the coldest and driest environments on Earth, and yet, they support surprisingly diverse and highly adapted microbial communities. Endolithic growth is one of the key adaptations to such extreme environments and often represents the dominant life-form. Despite growing scientific interest, little is known of the mechanisms that influence the assembly of endolithic microbiomes across these harsh environments. Here, we used metagenomics to examine the diversity and assembly of endolithic bacterial communities across Antarctica within different rock types and over a large elevation range. While granite supported richer and more heterogeneous communities than sandstone, elevation had no apparent effect on taxonomic richness, regardless of rock type. Conversely, elevation was clearly associated with turnover in community composition, with the deterministic process of variable selection driving microbial assembly along the elevation gradient. The turnover associated with elevation was modulated by geology, whereby for a given elevation difference, turnover was consistently larger between communities inhabiting different rock types. Overall, selection imposed by elevation and geology appeared stronger than turnover related to other spatially-structured environmental drivers. Our findings indicate that at the cold-arid limit of life on Earth, geology and elevation are key determinants of endolithic bacterial heterogeneity. This also suggests that warming temperatures may threaten the persistence of such extreme-adapted organism

Antarctic Cryptoendolithic Fungal Communities Are Highly Adapted and Dominated by Lecanoromycetes and Dothideomycetes

Endolithic growth is one of the most spectacular microbial adaptations to extreme environmental constraints and the predominant life-form in the ice-free areas of Continental Antarctica. Although Antarctic endolithic microbial communities are known to host among the most resistant and extreme-adapted organisms, our knowledge on microbial diversity and composition in this peculiar niche is still limited. In this study, we investigated the diversity and structure of the fungal assemblage in the cryptoendolithic communities inhabiting sandstone using a meta-barcoding approach targeting the fungal Internal Transcribed Sequence region 1 (ITS1). Samples were collected from 14 sites in the Victoria Land, along an altitudinal gradient ranging from 1,000 to 3,300 m a.s.l. and from 29 to 96 km distance to coast. Our study revealed a clear dominance of a ‘core’ group of fungal taxa consistently present across all the samples, mainly composed of lichen-forming and Dothideomycetous fungi. Pareto-Lorenz curves indicated a very high degree of specialization (F0 approximately 95%), suggesting these communities are highly adapted but have limited ability to recover after perturbations. Overall, both fungal community biodiversity and composition did not show any correlation with the considered abiotic parameters, potentially due to strong fluctuations of environmental conditions at local scales

The second International Symposium on Fungal Stress:ISFUS

The topic of 'fungal stress' is central to many important disciplines, including medical mycology, chronobiology, plant and insect pathology, industrial microbiology, material sciences, and astrobiology. The International Symposium on Fungal Stress (ISFUS) brought together researchers, who study fungal stress in a variety of fields. The second ISFUS was held in May 8-11 2017 in Goiania, Goias, Brazil and hosted by the Instituto de Patologia Tropical e Satide Pablica at the Universidade Federal de Goias. It was supported by grants from CAPES and FAPEG. Twenty-seven speakers from 15 countries presented their research related to fungal stress biology. The Symposium was divided into seven topics: 1. Fungal biology in extreme environments; 2. Stress mechanisms and responses in fungi: molecular biology, biochemistry, biophysics, and cellular biology; 3. Fungal photobiology in the context of stress; 4. Role of stress in fungal pathogenesis; 5. Fungal stress and bioremediation; 6. Fungal stress in agriculture and forestry; and 7. Fungal stress in industrial applications. This article provides an overview of the science presented and discussed at ISFUS-2017. (C) 2017 British Mycological Society. Published by Elsevier Ltd. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundacao de Amparo a Pesquisa do Estado de Goias of BrazilAlders English Serv, BR-74810908 Goiania, Go, BrazilUniv Fed Goias, Lab Biol Mol, Inst Ciencias Biol, BR-74690900 Goiania, Go, BrazilUniv Fed Sao Carlos, Dept Genet & Evolucao, Ctr Ciencias Biol & Saude, Lab Bioquim & Genet Aplicada, BR-90040060 Sao Carlos, SP, BrazilChinese Acad Sci, Shanghai Inst Plant Physiol & Ecol, CAS Key Lab Insect Dev & Evolutionary Biol, Shanghai 200032, Peoples R ChinaUniv Fed Rio Grande do Sul, Dept Mol Biol & Biotechnol, Ctr Biotechnol, BR-13565905 Porto Alegre, RS, BrazilUniv Saskatchewan, Coll Pharm & Nutr, Saskatoon, SK S7N 5E5, CanadaUniv Helsinki, Dept Agr Sci, POB 27, FI-00014 Helsinki, FinlandUniv Fed Rio de Janeiro, Inst Chem, BR-21941901 Rio De Janeiro, RJ, BrazilUniv Fed Goias, Inst Patol Trop & Saude Publ, BR-74605050 Goiania, Go, BrazilUniv Dundee, Sch Life Sci, Geomicrobiol Grp, Dundee DD1 5EH, ScotlandUniv Gottingen, Inst Microbiol & Genet, Dept Mol Microbiol & Genet, D-37077 Gottingen, GermanyUniv Gottingen, Gottingen Ctr Mol Biosci, D-37077 Gottingen, GermanyUniv Sao Paulo, Fac Ciencias Farmaceut Ribeirao Preto, Dept Anal Clin Toxicol & Bromatol, BR-14040903 Ribeirao Preto, SP, BrazilUniv Sao Paulo, Fac Ciencias Farmaceut Ribeirao Preto, Dept Ciencias Farmaceut, BR-14040903 Ribeirao Preto, SP, BrazilUniv Fed Sao Carlos, Dept Genet & Evolucao, Ctr Ciencias Biol & Saude, BR-13565905 Sao Carlos, SP, BrazilQueens Univ Belfast, Inst Global Food Secur, Sch Biol Sci, MBC, Belfast BT9 7BL, Antrim, North IrelandUtah State Univ, Dept Biol, Logan, UT 84322 USAGeisel Sch Med Dartmouth, Dept Mol & Syst Biol, Hanover, NH 03755 USAUniv Tuscia, Dept Ecol & Biol Sci DEB, I-01100 Viterbo, ItalyUniv Seville, Fac Biol, Dept Genet, Seville 41012, SpainUniv Estadual Paulista, Inst Quim, Dept Bioquim & Tecnol Quim, BR-14800060 Araraquara, SP, BrazilAIT Austrian Inst Technol GmbH, Ctr Hlth & Bioresources, Konrad Lorenz Str 24, A-3430 Tulin, AustriaCONICET Univ Nacl La Plata UNLP, Inst Invest Bioquim La Plata INIBIOLP, CCT La Plata Consejo Nacl Invest Cient & Tecn, Calles 60 & 120, RA-1900 La Plata, ArgentinaUniv Autonoma Metropolitana Iztapalapa, Dept Biotechnol, Mexico City 09340, DF, MexicoSwedish Univ Agr Sci, Uppsala Bioctr, Dept Forest Mycol & Plant Pathol, Box 7026, S-75007 Uppsala, SwedenUniv Estadual Maringa, Dept Biochem, BR-87020900 Maringa, PR, BrazilUniv Estadual Paulista, Inst Quim, Dept Bioquim & Tecnol Quim, BR-14800060 Araraquara, SP, BrazilFAPESP: 2010/06374-1FAPESP: 2013/50518-6FAPESP: 2014/01229-4CNPq: PQ2 302312/2011-0CNPq: PQ1D 308436/2014-8CAPES: PAEP 88881.123209/2016-01Fundacao de Amparo a Pesquisa do Estado de Goias of Brazil: 20171026700011

Life beyond Earth: the antarctic black fungus in planetary simulations

The cryptoendolithic black fungus Cryomyces antarcticus inhabits the ice-free area of the Antarctic McMurdo Dry Valleys, one of the best terrestrial analogue environment for Mars. There, conditions on rock surface are often incompatible with life; hence, microbes develop within porous rocks as last chance for survival. The almost complete isolation over a timescale of evolutionary significance led to the evolution of unique, extremely adapted and resistant, genotypes. C. antarcticus is particularly skilled in stress tolerance being able to tolerate injuries well beyond the harsh conditions of its natural environment. Because of its uncommon resistance, the fungus has been chosen as eukaryotic model for astrobiological studies to test the endurance of eukaryotic cells to space conditions. In the experiment here reported, the fungus C. antarcticus was exposed, in the frame of the STARLIFE irradiation campaign, to different types and qualities of ionizing radiation with different linear energy transfer values (0.2 to 200 keV/µm). Irradiation with up to 1 kGy of accelerated He, Ar and Fe ions, and 55.57 kGy of gamma rays (60Cobalt). Single gene PCR, RAPD fingerprinting, qPCR and PMA coupled with qPCR analyses reveal minimal damage to DNA or plasma membranes induced by the treatments. This experiments further confirm the stunning stress tolerance of the fungus and its high relevance in astrobiological investigations, including the search for life on Mars, the reliability of the Lithopanspermia theory, and the estimation of planetary contamination risk