Permafrost Ice Wedge Research Articles

In Situ Field Sequencing and Life Detection in Remote (79°26'N) Canadian High Arctic Permafrost Ice Wedge Microbial Communities.

Significant progress is being made in the development of the next generation of low cost life detection instrumentation with much smaller size, mass and energy requirements. Here, we describe in situ life detection and sequencing in the field in soils over laying ice wedges in polygonal permafrost terrain on Axel Heiberg Island, located in the Canadian high Arctic (79°26′N), an analog to the polygonal permafrost terrain observed on Mars. The life detection methods used here include (1) the cryo-iPlate for culturing microorganisms using diffusion of in situ nutrients into semi-solid media (2) a Microbial Activity Microassay (MAM) plate (BIOLOG Ecoplate) for detecting viable extant microorganisms through a colourimetric assay, and (3) the Oxford Nanopore MinION for nucleic acid detection and sequencing of environmental samples and the products of MAM plate and cryo-iPlate. We obtained 39 microbial isolates using the cryo-iPlate, which included several putatively novel strains based on the 16S rRNA gene, including a Pedobacter sp. (96% closest similarity in GenBank) which we partially genome sequenced using the MinION. The MAM plate successfully identified an active community capable of L-serine metabolism, which was used for metagenomic sequencing with the MinION to identify the active and enriched community. A metagenome on environmental ice wedge soil samples was completed, with base calling and uplink/downlink carried out via satellite internet. Validation of MinION sequencing using the Illumina MiSeq platform was consistent with the results obtained with the MinION. The instrumentation and technology utilized here is pre-existing, low cost, low mass, low volume, and offers the prospect of equipping micro-rovers and micro-penetrators with aggressive astrobiological capabilities. Since potentially habitable astrobiology targets have been identified (RSLs on Mars, near subsurface water ice on Mars, the plumes and oceans of Europa and Enceladus), future astrobiology missions will certainly target these areas and there is a need for direct life detection instrumentation.

Northeast Siberian ice wedges confirm Arctic winter warming over the past two millennia

Arctic climate has experienced major changes over the past millennia that are not fully understood in terms of their controls and seasonality. Stable isotope data from ice wedges in permafrost provide unique information on past winter climate. Recently, an ice-wedge record from the Lena River Delta suggested for the first time that Siberian winter temperatures increased throughout the Holocene, contradicting most other Arctic palaeoclimate reconstructions which are likely biased towards the summer. However, the representativeness of this single record and the spatial extent of its reconstructed winter warming signal is unclear. Here, we present a new winter temperature record based on paired stable oxygen (δ18O) and radiocarbon age data spanning the last two millennia from the Oyogos Yar coast in northeast Siberia. The record confirms the long-term winter warming signal as well as the unprecedented temperature rise in recent decades. This confirmation demonstrates that winter warming over the last millennia is a coherent feature in the northeastern Siberian Arctic, supporting the hypothesis of an insolation-driven seasonal Holocene temperature evolution followed by a strong warming likely related to anthropogenic forcing.

Isoscapes of δ18O and δ2H reveal climatic forcings on Alaska and Yukon precipitation

AbstractSpatially extensive Arctic stable isotope data are sparse, inhibiting the climatic understanding required to interpret paleoclimate proxy records. To fill this need, we constrained the climatic and physiographic controls on δ18O and δD values of stream waters across Alaska and the Yukon to derive interpolated isoscape maps. δ18O is strongly correlated to winter temperature parameters and similarity of the surface water line (δ2H = 8.0 × δ18O + 6.4) to the Global Meteoric Water Line suggests stream waters are a proxy for meteoric precipitation. We observe extreme orographic δ18O decreases and a trans‐Alaskan continental gradient of −8.3‰ 1000 km−1. Continental gradients are high in coastal zones and low in the interior. Localized δ18O increases indicate inland air mass penetration via topographic lows. Using observed δ18O/temperature gradients, we show that δ18O decreases in a ∼24 ka permafrost ice wedge relative to the late Holocene indicate mean annual and coldest quarter temperature reductions of 8.9 ± 1.7°C and 17.2 ± 3.2°C, respectively.

Increase in Bacterial Colony Formation from a Permafrost Ice Wedge Dosed with a Tomitella biformata Recombinant Resuscitation-Promoting Factor Protein.

Resuscitation-promoting factor (Rpf) is a protein that has been found in a number of different Actinobacteria species and has been shown to promote the growth of active cells and resuscitate dormant (non-dividing) cells. We previously reported the biological activity of an Rpf protein in Tomitella biformata AHU 1821T, an Actinobacteria isolated from a permafrost ice wedge. This protein is excreted outside the cell; however, few studies have investigated its contribution in environmental samples to the growth or resuscitation of bacteria other than the original host. Therefore, the aim of the present study was to determine whether Rpf from T. biformata impacted the cultivation of other bacteria from the permafrost ice wedge from which it was originally isolated. All experiments used recombinant Rpf proteins produced using a Rhodococcus erythropolis expression system. Dilutions of melted surface sterilized ice wedge samples mixed with different doses of the purified recombinant Rpf (rRpf) protein indicated that the highest concentration tested, 1250 pM, had a significantly (p <0.05) higher number of CFUs on agar plates after 8 d, approximately 14-fold higher than that on control plates without rRpf. 16S rRNA gene sequences revealed that all the colonies on plates were mainly related to Brevibacterium antiquum strain VKM Ac-2118 (AY243344), with 98–99% sequence identity. This species is also a member of the phylum Actinobacteria and was originally isolated from Siberian permafrost sediments. The results of the present study demonstrated that rRpf not only promoted the growth of T. biformata from which it was isolated, but also enhanced colony formation by another Actinobacteria in an environmental sample.

Resuscitation Promoting Factor (Rpf) from &lt;i&gt;Tomitella biformata&lt;/i&gt; AHU 1821&lt;sup&gt;T&lt;/sup&gt; Promotes Growth and Resuscitates Non-Dividing Cells

Functional variation of Rpf, a growth factor found exclusively in Actinobacteria, is differentiated by its source and amino acid sequences. Only purified Rpf proteins from three species have been studied so far. To seek new Rpfs for use in future studies to understand their role in Actinobacteria, the objective of this study was to identify rpf gene homologs in Tomitella biformata AHU 1821T, a novel Actinobacteria isolated from permafrost ice wedge. Amplification using degenerate primers targeting the essential Rpf domain led to the discovery of a new rpf gene in T. biformata. Gene structure and the deduced Rpf domain amino acid sequence indicated that this rpf gene was not identical to previously studied Rpf. Phylogenetic analysis placed T. biformata Rpf in a monophyletic branch in the RpfB subfamily. The deduced amino acid sequence was 44.9% identical to RpfB in Mycobacterium tuberculosis, the closest functionally tested Rpf. The gene was cloned and expressed in Escherichia coli; the recombinant Rpf protein (rRpf) promoted the growth of dividing cells and resuscitated non-dividing cells of T. biformata. Compared to other studies, this Rpf was required at higher concentrations to promote its growth and to resuscitate itself from a non-dividing state. The resuscitation function was likely due to the highly conserved Rpf domain. This study provides evidence that a genetically unique but functional Rpf can be found in novel members of Actinobacteria and can lead to a better understanding of bacterial cytokines in this phylum.

Glaciibacter superstes gen. nov., sp. nov., a novel member of the family Microbacteriaceae isolated from a permafrost ice wedge

Gram-positive, aerobic, non-spore-forming, irregular rod-shaped bacteria, designated strains AHU1791(T) and AHU1810, were isolated from a permafrost ice wedge in Alaska. Cells were motile by means of a polar flagellum. The strains were psychrophilic, growing at -5 to 25 degrees C. Phylogenetic analysis of 16S rRNA gene sequences indicated that the ice-wedge isolates formed a clade distinct from other genera affiliated with the family Microbacteriaceae. The novel strains showed highest levels of 16S rRNA gene sequence similarity with members of the genera Agreia and Subtercola (95.6-95.9 %). The level of 16S rRNA gene sequence similarity between strains AHU1791(T) and AHU1810 was 99.8 %. The cell-wall peptidoglycan type of the two strains was B2gamma, containing 2,4-diaminobutyric acid as the diagnostic amino acid. The predominant menaquinones were MK-12 and MK-13 (strain AHU1791(T)) and MK-11 and MK-12 (strain AHU1810). The major fatty acids of the two strains were 12-methyl tetradecanoic acid (anteiso-C(15 : 0)), 14-methyl hexadecanoic acid (anteiso-C(17 : 0)), 14-methyl pentadecanoic acid (iso-C(16 : 0)) and 13-methyl tetradecanoic acid (iso-C(15 : 0)). The DNA G+C contents of strains AHU1791(T) and AHU1810 were approximately 65 mol%. These phenotypic characteristics differentiated the ice-wedge strains from their closest phylogenetic neighbours, namely Subtercola boreus and the two recognized species of the genus Agreia. The sequences of the housekeeping genes coding for DNA gyrase subunit B (gyrB), RNA polymerase subunit B (rpoB) and recombinase A (recA) were almost identical between strains AHU1791(T) and AHU1810. Although the predominant menaquinones found in strains AHU1791(T) and AHU1810 were different, no other distinct differences were found with regard to other phenotypic and genotypic characteristics, indicating that the two strains were members of the same species. Accordingly, strains AHU1791(T) and AHU1810 are considered to represent a single novel species of a new genus, for which the name Glaciibacter superstes gen. nov., sp. nov. is proposed. The type strain of Glaciibacter superstes is AHU1791(T) (=DSM 21135(T) =NBRC 104264(T)).

Dating of syngenetic ice wedges in permafrost with 36Cl

A new method of permafrost dating with the cosmogenic radionuclide 36Cl is presented. In the first application, syngenetic ice wedges are dated using the ratio of 36Cl and Cl concentrations in ice as the signal. 36Cl is produced in the atmosphere by nuclear reactions of cosmic rays on argon. Stable chlorine enters the atmosphere from the oceans. Their ratio does not depend on chloride concentration in precipitations and on sublimation of snow. In situ production of 36Cl in permafrost ice via cosmic ray-induced reactions and neutron capture are calculated and the dating age limit is estimated as 3 million years. 36Cl/Cl ratios in permafrost samples from cape Svyatoy Nos (Laptev Sea coast), North-Eastern Siberia, are measured by accelerator mass spectrometry. Analysis of the first results and the calculated dates support the feasibility of the 36Cl permafrost dating method

Phylogenetic Analysis of Bacteria Preserved in a Permafrost Ice Wedge for 25,000 Years

Phylogenetic analysis of bacteria preserved within an ice wedge from the Fox permafrost tunnel was undertaken by cultivation and molecular techniques. The radiocarbon age of the ice wedge was determined. Our results suggest that the bacteria in the ice wedge adapted to the frozen conditions have survived for 25,000 years.

Analysis of microorganisms trapped in permafrost ice wedge by cultivation-based and molecular techniques:

Analysis of microorganisms trapped in permafrost ice wedge by cultivation-based and molecular techniques:

Ice-wedges in Permafrost, Maranbio Island, Antarctic Peninsula

Ice-wedges in Permafrost, Maranbio Island, Antarctic Peninsula