Transitory Microbial Habitat in the Hyperarid Atacama Desert

Traces of life are nearly ubiquitous on Earth. However, a central unresolved question is whether these traces always indicate an active microbial community or whether, in extreme environments, such as hyperarid deserts, they instead reflect just dormant or dead cells. Although microbial biomass and diversity decrease with increasing aridity in the Atacama Desert, we provide multiple lines of evidence for the presence of an at times metabolically active, microbial community in one of the driest places on Earth. We base this observation on four major lines of evidence: a physico-chemical characterization of the soil habitability after an exceptional rain event, identified biomolecules indicative of potentially active cells [e.g., presence of ATP, phospholipid fatty acids (PLFAs), metabolites, and enzymatic activity], measurements of in situ replication rates of genomes of uncultivated bacteria reconstructed from selected samples, and microbial community patterns specific to soil parameters and depths. We infer that the microbial populations have undergone selection and adaptation in response to their specific soil microenvironment and in particular to the degree of aridity. Collectively, our results highlight that even the hyperarid Atacama Desert can provide a habitable environment for microorganisms that allows them to become metabolically active following an episodic increase in moisture and that once it decreases, so does the activity of the microbiota. These results have implications for the prospect of life on other planets such as Mars, which has transitioned from an earlier wetter environment to today's extreme hyperaridity. [Abstract copyright: Copyright © 2018 the Author(s). Published by PNAS.

Fungal Planet description sheets: 1383-1435

Novel species of fungi described in this study include those from various countries as follows: Australia, Agaricus albofoetidus, Agaricus aureoelephanti and Agaricus parviumbrus on soil, Fusarium ramsdenii from stem cankers of Araucaria cunninghamii, Keissleriella sporoboli from stem of Sporobolus natalensis, Leptosphaerulina queenslandica and Pestalotiopsis chiaroscuro from leaves of Sporobolus natalensis, Serendipita petricolae as endophyte from roots of Eriochilus petricola, Stagonospora tauntonensis from stem of Sporobolus natalensis, Teratosphaeria carnegiei from leaves of Eucalyptus grandis x E. camaldulensis and Wongia ficherai from roots of Eragrostis curvula. Canada, Lulworthia fundyensis from intertidal wood and Newbrunswickomyces abietophilus (incl. Newbrunswickomyces gen. nov.)on buds of Abies balsamea. Czech Republic, Geosmithia funiculosa from a bark beetle gallery on Ulmus minor and Neoherpotrichiella juglandicola (incl. Neoherpotrichiella gen. nov.)from wood of Juglans regia. France, Aspergillus rouenensis and Neoacrodontium gallica (incl. Neoacrodontium gen. nov.)from bore dust of Xestobium rufovillosum feeding on Quercus wood, Endoradiciella communis (incl. Endoradiciella gen. nov.)endophyticin roots of Microthlaspi perfoliatum and Entoloma simulans on soil. India, Amanita konajensis on soil and Keithomyces indicus from soil. Israel, Microascus rothbergiorum from Stylophora pistillata. Italy, Calonarius ligusticus on soil. Netherlands , Appendopyricularia juncicola (incl. Appendopyricularia gen. nov.), Eriospora juncicola and Tetraploa juncicola on dead culms of Juncus effusus, Gonatophragmium physciae on Physcia caesia and Paracosmospora physciae (incl. Paracosmospora gen. nov.)on Physcia tenella, Myrmecridium phragmitigenum on dead culm of Phragmites australis, Neochalara lolae on stems of Pteridium aquilinum, Niesslia nieuwwulvenica on dead culm of undetermined Poaceae, Nothodevriesia narthecii (incl. Nothodevriesia gen. nov.) on dead leaves of Narthecium ossifragum and Parastenospora pini (incl. Parastenospora gen. nov.)on dead twigs of Pinus sylvestris. Norway, Verticillium bjoernoeyanum from sand grains attached to a piece of driftwood on a sandy beach. Portugal, Collybiopsis cimrmanii on the base of living Quercus ilex and amongst dead leaves of Laurus and herbs. South Africa , Paraproliferophorum hyphaenes (incl. Paraproliferophorum gen. nov.) on living leaves of Hyphaene sp. and Saccothecium widdringtoniae on twigs of Widdringtonia wallichii. Spain, Cortinarius dryosalor on soil, Cyphellophora endoradicis endophytic in roots of Microthlaspi perfoliatum, Geoglossum laurisilvae on soil, Leptographium gemmatum from fluvial sediments, Physalacria auricularioides from a dead twig of Castanea sativa , Terfezia bertae and Tuber davidlopezii in soil. Sweden, Alpova larskersii, Inocybe alpestris and Inocybe boreogodeyi on soil. Thailand, Russula banwatchanensis, Russula purpureoviridis and Russula lilacina on soil. Ukraine, Nectriella adonidis on over wintered stems of Adonis vernalis. USA, Microcyclus jacquiniae from living leaves of Jacquinia keyensis and Penicillium neoherquei from a minute mushroom sporocarp. Morphological and culture characteristics are supported by DNA barcodes

Biodiversity of methanogenic archaea in permafrost affected soils of the Lena Delta, Siberia

Hydromorphic arctic tundra soils are a very important source of atmospheric methane (CH4) which is according to CO2 the most climate relevant greenhouse gas.Wet tundra environments are generally a net carbon sink since the predominant environmental conditions reduce decomposition of organic matter and support a carbon accumulation. More than 14 % of the global terrestrial carbon is stored in soils and sediments of Arctic permafrost environments.Most of the climate models predict a global warming for the next century, which will be shown in deeper and longer thaw processes in the active layer of permafrost soils in the High Arctic and probably of a higher rate of degradation of organic matter and emission of methane and carbon dioxide.The microbial methane production (methanogenesis) is one of the most prominent microbiological processes during the anaerobic decomposition of organic matter. A group of strictly anaerobic organisms called methanogenic archaea is responsible for methanogenesis. The methanogenic archaea use the metabolism end products of bacteria involved in the anaerobic foodchain, which transform complex organic molecules into simple compounds like H2, CO2, acetate, formiate.After its production methane is partly oxidized either in the aerobic top layer of permafrost soils or in the aerobic rhizosphere by highly specialized Proteobacteria, belonging to the group of methanotrophic bacteria. They are using CH4 as the sole carbon source, while energy is gained by the oxidation of CH4 to CO2.In this study the community structure of methanogenic archaea was analyzed by polymerase chain reaction (PCR) using a nested primer approach with two different internal primer sets following denaturing gradient gel electrophoresis (DGGE) and sequencing of 16S rRNA gene fragments. These modern molecular ecological methods allow to study the microbial community including uncultivable microorganisms.To investigate the archaeal community structure samples from three geomorphological different sites were taken:(i) a low centre polygon, (ii) a floodplain (both sites are located on Samoylov Island, Lena Delta) and (iii) a thermoerosion valley (Cape Mammontovy Klyk, ca. 400 km northwest of Samoylov). DNA was extracted directly from soils or from enrichment cultures. Samples for enrichment were taken from two different depths and were incubated under different conditions concerning temperature, salt content and substrates.The comparsion of the three different habitats showed clear differences between the composition of the methanogenic Archaea in the different environments. Both places on Samoylov showed a higher diversity than samples from Mammontovy Klyk. Results also indicate that there is a shift in the community structure from the top to the bottom of the active layer.The DGGE method is a very useful tool to get a fast overview about the composition of microbial communities in complex habitats. It can be also used to controll the enrichment and isolation of pure bacterial cultures.But nevertheless for detailed information about the methanogenic diversity the construction of a clone libary should be the next aim

Antarctic microbial communities in mineral deposits on Livingston Island, South Shetland Islands

Livingston Island, located at the tip of the Antarctic Peninsula, is characterised by an oceanic polar climate with temperatures above 0°C during the austral summer and a mean annual precipitation between 400 and 500 mm. Under these conditions a soil formation can be observed and lichens, mosses and some higher plants are able to grow in this environment. With cultivation-independent methods, it is possible to analyse complex microbial networks in the face of diversity, abundance, ecology and their reaction on climate change. Here, we investigated the bacterial community structure of different habitats located on Livingston Island by polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) to get a first insight in the diversity of bacteria existing under these conditions. The aim of these studies is to identify the main microbial players in nutrient turnover within periglacial ecosystems of Antarctica.One transect and four separate profiles were sampled near the Bulgarian station St. Kliment Ohridski (62°38`S/60°21`W). Two soil profiles were characterised by permafrost. The investigated mineral soils showed mostly gravely sand texture. Moisture content of the soils ranged from 2.6% up to 15.6% and was partly quite variable within the different profiles. The values of total carbon and nitrogen were extremely low with <0.10 to 0.46% and <0.10%, respectively, except for the upper layers of the profiles T1-1 and T1-4 that were covered by mosses. PLFA concentration decreased with increasing depth, which correlates well with the TC values. DGGE patterns from amplification of DNA showed large varieties in the vertical profiles and between the different sites. Most sequences recovered from Antarctic soil profiles belong to the Bacteriodetes and to the Acidobacteria phylum.DGGE pictures showed a high diversity in most of the samples. The main influence on heterotrophic microbial growth and activity in low-nutrient habitats is probably the availability of organic compounds. Water can also be a limiting factor, but microorganisms seem to be well adapted to these conditions as it can be derived from the DGGE pattern. It is conceivable that the ways of C and N cycling in cold Antarctic habitats are short and that cold-adapted microorganisms might play a major role for the ecosystem development. To compare arctic and antarctic microbial communities phylogenetic investigations will be done using clone libraries for both Bacteria and Archaea