Antarctica Research Articles

Aerobiology in High Latitudes: Evidence of Bacteria Acting as Tracer of Warm Air Mass Advection reaching Northern Antarctic Peninsula.

Despite the extent use of geochemical tracers to track warm air mass origin reaching the Antarctic continent, we present here evidences that microorganisms being transported by the atmosphere and deposited in fresh snow layers of Antarctic ice sheets do act as tracers of air mass advection from the Southern Patagonia region to Northern Antarctic Peninsula. We combined atmospheric circulation data with microorganism content in snow/firn samples collected in two sites of the Antarctic Peninsula (King George Island/Wanda glacier and Detroit Plateau) by using flow cytometer quantification. In addition, we cultivated, isolated and submitted samples to molecular sequencing to precise species classification. Viable gram-positive bacteria were found and recovered in different snow/firn layers samples, among dead and living cells, their number concentration was compared to northern wind component, stable isotopes of oxygen, d18O, and the concentration of crustal elements (Fe, Ti and Ca). Use of satellite images combined with air mass back-trajectory analysis obtained from the NOAA/ HYSPLIT model corroborated the results.

HISTORICAL BIOGEOGRAPHY OF THE AUSTRAL HORNWORT GENUS PHAEOMEGACEROS (DENDROCEROTACEAE, ANTHOCEROTOPHYTA)

The transoceanic disjunct distributions between Australasia and Austral America have been observed in many plant groups. The processes behind these disjunct distributions remain a source of debate due to differences in species vagility, biogeographical history, and complex geological and climatic changes. We address the phylogenetic relationships and biogeographical history of the austral hornwort genus Phaeomegaceros based on eight molecular markers from the three genomes (nuclear: phytochrome, mitochondrial: nad5, and chloroplast: rbcL, trnL intron, trnL-trnF spacer, rps4 gene, rps4-trnS spacer, and matK gene). With ten taxa based on morphological and molecular data, the three phylogenetic analyses supported the genus Phaeomegaceros as monophyletic. Phaeomegaceros is composed of two major clades corresponding to the New Zealand species, which presents a conspicuous trilete mark with one depression in the middle of the spore’s proximal face, and the Austral American species, which lack this middle depression. Dating and biogeographical analyses indicate that the Phaeomegaceros ancestral area was New Zealand and Antarctica in the Late Cretaceous (53.51 Ma, HPD 95% = 31.64–72.63). While Austral American species diverged during the Eocene. We speculate that climatic fluctuations in the Antarctic continent during the middle to late-Miocene led to the isolation of Phaeomegaceros taxa with both processes (dispersal events and vicariance) acting on the independent evolution of the disjunct clades. Furthermore, recent diversification of Phaeomegaceros taxa in Austral America and range expansion to northern Andes and oceanic islands, are explained by dispersal events and subsequent cladogenesis coinciding with the uplift of the Andes and the formation of volcanic oceanic islands (Juan Fernandez and Tristan da Cunha).

Review of Scientific Research Conducted in Horseshoe Island Where Potential Place for Turkish Antarctic Base

The Antarctic Continent, which has the most challenging environmental-field conditions such as high cost logistics needs, extreme weather events, and natural elements that makes impossible to live for most of the living things including humans, in terms of to carry out scientific research, has hosting scientific projects of Turkish scientists in recent years. Turkish Antarctic Expeditions, continuing since 2017, have concentrated on Horseshoe Island, located in the Marguerite Bay on the west coast of the Antarctic Peninsula, where ice melts are recorded the most due to global climate change. Since Turkey plans to establish a scientific station in the upcoming years on Horseshoe Island, reviewing all disciplines in the literature of polar research that have been done and can be done on the island is of great importance in the national polar strategy and in laying the foundation of scientific research to be carried out in the future. In this study, the researches of especially British and Turkish scientists in the region were reviewed: it was seen that many interdisciplinary studies and social science projects were also carried out. Despite the many scientific projects completed, it is seen among the results of this study that many polar research disciplines that can be applied and can give direction to world science can still be conduct on the region.

Gene Expression Profiling of Trematomus bernacchii in Response to Thermal and Stabling Stress

The Antarctic continent is one of the most pristine environments on planet Earth, yet one of the most fragile and susceptible to the effects of the ongoing climate change. The overwhelming majority of the components of Antarctic marine trophic chain are stenotherm organisms, highly adapted to the extreme, but extremely stable, freezing temperatures of the Antarctic ocean, which have not changed significantly during the past fifteen million years. Notothenioid fishes are the most abundant representatives of ichthyofauna at these latitudes, being ubiquitously found in coastal areas across the entire continent. While different Antarctic fish species have been previously subjected to studies aimed at defining their range of thermal tolerance, or at studying the response to acute thermal stress, just a handful of authors have investigated the effects of the exposure to a moderate increase of temperature, falling within the expected forecasts for the next few decades in some areas of the Antarctica. Here, the emerald rockcod Trematomus bernacchii was used as a model species to investigate the effects of a 20-day long exposure to a +1.5 °C increase in the brain, gills and skeletal muscle, using a RNA-sequencing approach. In parallel, the experimental design also allowed for assessing the impact of stabling (including acclimation, the handling of fishes and their confinement in tanks during the experimental phase) on gene expression profiling. The results of this study clearly identified the brain as the most susceptible tissue to heat stress, with evidence of a time-dependent response dominated by an alteration of immune response, protein synthesis and folding, and energy metabolism-related genes. While the gills displayed smaller but still significant alterations, the skeletal muscle was completely unaffected by the experimental conditions. The stabling conditions also had an important impact on gene expression profiles in the brain, suggesting the presence of significant alterations of the fish nervous system, possibly due to the confinement to tanks with limited water volume and of the restricted possibility of movement. Besides providing novel insights in the molecular mechanisms underlying thermal stress in notothenioids, these findings suggest that more attention should be dedicated to an improved design of the experiments carried out on Antarctic organism, due to their extreme susceptibility to the slightest environmental alterations.

Antarctic fungi with antibiotic potential isolated from Fort William Point, Antarctica

The Antarctic continent is one of the most inhospitable places on earth, where living creatures, mostly represented by microorganisms, have specific physiological characteristics that allow them to adapt to the extreme environmental conditions. These physiological adaptations can result in the production of unique secondary metabolites with potential biotechnological applications. The current study presents a genetic and antibacterial characterization of four Antarctic fungi isolated from soil samples collected in Pedro Vicente Maldonado Scientific Station, at Fort William Point, Greenwich Island, Antarctica. Based on the sequences of the internal transcribed spacer (ITS) region, the fungi were identified as Antarctomyces sp., Thelebolus sp., Penicillium sp., and Cryptococcus gilvescens. The antibacterial activity was assessed against four clinical bacterial strains: Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, and Staphylococcus aureus, by a modified bacterial growth inhibition assay on agar plates. Results showed that C. gilvescens and Penicillium sp. have potential antibiotic activity against all bacterial strains. Interestingly, Thelebolus sp. showed potential antibiotic activity only against E. coli. In contrast, Antarctomyces sp. did not show antibiotic activity against any of the bacteria tested under our experimental conditions. This study highlights the importance of conservation of Antarctica as a source of metabolites with important biomedical applications.

Meta‐analysis of Antarctic phylogeography reveals strong sampling bias and critical knowledge gaps

Much of Antarctica's highly endemic terrestrial biodiversity is found in small ice‐free patches. Substantial genetic differentiation has been detected among populations across spatial scales. Sampling is, however, often restricted to commonly‐accessed sites and we therefore lack a comprehensive understanding of broad‐scale biogeographic patterns, which could impede forecasts of the nature and impacts of future change. Here, we present a synthesis of published genetic studies across terrestrial Antarctica and the broader Antarctic region, aiming to identify current biogeographic patterns, environmental drivers of diversity and future research priorities. A database of all published genetic research from terrestrial fauna and flora (excl. microbes) across the Antarctic region was constructed. This database was then filtered to focus on the most well‐represented taxa and markers (mitochondrial COI for fauna, and nuclear ITS for flora). The final dataset comprised 7222 records, spanning 153 studies of 335 different species. There was strong taxonomic bias towards flowering plants (52% of all floral data sets) and springtails (54% of all faunal data sets), and geographic bias towards the Antarctic Peninsula and Victoria Land. Recent connectivity between the Antarctic continent and neighbouring landmasses, such as South America and the Southern Ocean Islands (SOIs), was inferred for some groups, but patterns observed for most taxa were strongly influenced by sampling biases. Above‐ground wind speed and habitat heterogeneity were positively correlated with genetic diversity indices overall though environment was a generally poor predictor of genetic diversity. The low resolution and variable coverage of data may also have reduced the power of our comparative inferences. In the future, higher‐resolution data, such as genomic SNPs and environmental modelling, alongside targeting sampling of remote sites and under sampled taxa, will address current knowledge gaps and greatly advance our understanding of evolutionary processes across the Antarctic region.

Southern Ocean biogenic blooms freezing-in Oligocene colder climates

Crossing a key atmospheric CO2 threshold triggered a fundamental global climate reorganisation ~34 million years ago (Ma) establishing permanent Antarctic ice sheets. Curiously, a more dramatic CO2 decline (~800–400 ppm by the Early Oligocene(~27 Ma)), postdates initial ice sheet expansion but the mechanisms driving this later, rapid drop in atmospheric carbon during the early Oligocene remains elusive and controversial. Here we use marine seismic reflection and borehole data to reveal an unprecedented accumulation of early Oligocene strata (up to 2.2 km thick over 1500 × 500 km) with a major biogenic component in the Australian Southern Ocean. High-resolution ocean simulations demonstrate that a tectonically-driven, one-off reorganisation of ocean currents, caused a unique period where current instability coincided with high nutrient input from the Antarctic continent. This unrepeated and short-lived environment favoured extreme bioproductivity and enhanced sediment burial. The size and rapid accumulation of this sediment package potentially holds ~1.067 × 1015 kg of the ‘missing carbon’ sequestered during the decline from an Eocene high CO2-world to a mid-Oligocene medium CO2-world, highlighting the exceptional role of the Southern Ocean in modulating long-term climate.

Powering Research Stations in Antarctica [History

In the beginning of the 20th century, exploration on the continent of Antarctica greatly tested the capability of ship builders to construct rugged wooden ships specifically for polar work. The propulsion systems for these vessels were often equipped with triple-expansion steam engines using coal for fuel, and the ships were barquentine rigged so they could carry significant cargo while maintaining adequate speed under most wind conditions. Fuel oil from rendered whale blubber was carried on board to fire their blubber stoves for cooking and space heating [1]. The crew and passengers consisted of polar explorers, naturalists, scientists, sailors, and adventurers who navigated treacherous ice-packed waters to be the first to attempt to establish a land-based scientific station or to ultimately cross the entire South Polar continent from sea to sea. The experienced whalers who acquired first-hand experience sailing these waters in less sophisticated ships while pursuing their trade were often consulted by the unfamiliar explorers about the challenges they would face in these treacherous waters. They would also provide recommendations on safer seasonal routes to navigate to avoid dangerous ice conditions that could make ship travel near impossible, challenging human survival on the continent of Antarctica.

Aerobiology over the Southern Ocean - Implications for bacterial colonization of Antarctica.

Parts of the Antarctic are experiencing dramatic ecosystem change due to rapid and record warming, which may weaken biogeographic boundaries and modify dispersal barriers, increasing the risk of biological invasions. In this study, we collected air samples from 100 locations around the Southern Ocean to analyze bacterial biodiversity in the circumpolar air around the Antarctic continent, as understanding dispersal processes is paramount to assessing the risks of microbiological invasions. We also compared the Southern Ocean air bacterial biodiversity to non-polar ecosystems to identify the potential origin of these Southern Ocean air microorganisms. The bacterial diversity in the air had both local and global origins and presented low richness overall but high heterogeneity, compatible with a scenario whereby samples are composed of a suite of different species in very low relative abundances. Only 4% of Amplicon Sequence Variants (ASVs) were identified in both polar and non-polar air masses, suggesting that the polar air mass over the Southern Ocean can act as a selective dispersal filter. Furthermore, both microbial diversity and community structure both varied significantly with meteorological data, suggesting that regional bacterial biodiversity could be sensitive to changes in weather conditions, potentially altering the existing pattern of microbial deposition in the Antarctic.

Modelling MODIS Land Surface Temperature Change in Antarctica from 2000 to 2019 Using Cubic Spline Model

Abstract Land surface temperature (LST) data derived from the satellite is increasingly required to supplement the limited weather stations for assessing temperature trends in Antarctica. This study analyses the LST based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s satellite length from 2000 to 2019 at a systematic 108 sub-regions. Antarctica was divided into 12 regions, each consisting of 9 sub-regions. A cubic spline model adjusted for seasonal patterns and the autoregressive process adjusted for time series correlation. Change in LST in sub-regions was estimated by fitting the simple linear model, while cycle and acceleration were estimated using cubic spline models. Multivariate regression adjusted for spatial correlation and was used to estimate the LST increase in regions. The seasonal patterns for all 108 sub-regions were found to be quite similar. Out of 108 sub-regions, only 30 had statistically significant decreasing trends. The 12 regions showed that most temperature trends decreased, although only 5 regions were statistically significant. The results for the entire Antarctic continent showed a statistically significant decrease and a 95% confidence interval ranging from -0.668 to -0.068 °C per decade. Keywords: Land surface temperature, MODIS, Cubic spline, Autocorrelations, Spatial correlations

Production of biosurfactants by bacteria collected in soil contaminated by diesel oil on the Antarctic Continent

Currently, the whole world strives for a sustainable development to avoid the depletion of natural resources. Therefore, the search for new biotechnological products such as biosurfactants has generated interest due to its low toxicity, biodegradability and ecological acceptability. Furthermore, biosurfactants have several applications such as emulsification, wettability, foaming, cleaning, and reduction of crude oil viscosity. The objective of this work was to identify the bacteria collected in Antarctica and evaluate their capacity to produce biosurfactants. In this study, bacteria collected in diesel contaminated soil around the Comandante Ferraz Antarctic Station were identified (Rhodococcus erythropolis, Rhizobium radiobacter, Microbacterium liquefacien, Pseudomonas libanensis and Pseudomonas veronii) and analyses were carried out to confirm whether these bacteria produce biosurfactants. Interestingly, the compounds isolated from the bacteria showed droplet propagation and reduced the surface tension of the water, which are properties of biosurfactants. Furthermore, these compounds showed carbohydrates in their molecular composition. Given these findings, these species have potential application in biotechnological areas, such as bioremediation of environments contaminated by diesel oil and in cosmetic and personal care as emulsifier. In addition, the use of diesel oil waste by bacteria as a carbon source becomes an attractive alternative because it reduces environmental contamination and has a low cost.

A DETERMINATION OF THE MOTION BASED ON GNSS OBSERVATIONS BETWEEN 2000 AND 2021 BY USING THE IGS POINTS ON THE POLAR REGIONS

People are fascinated today more than ever by the polar regions of the Earth. One reason for this is that wide expanses of the Arctic and Antarctic have not been explored and are therefore still viewed as frontier regions. Another is that they both have very diverse histories with regard to their origins and ice formation. Their numerous aspects still pose many puzzles for science today. The regions of the Earth designated as polar are those areas located between the North or South Pole and the Arctic or Antarctic Circles, respectively. The northern polar region, called the Arctic, encompasses the Arctic Ocean and a portion of some surrounding land masses. The southern polar region, called the Antarctic, contains the continent of Antarctica and areas of the surrounding Southern Ocean. In this paper three tests (2000, 2010 and 2021) of continuous GNSS data recorded by 8 permanent International GPS Service (IGS) stations in both Polar Regions have been processed by using CSRS-PPP Software for geodetic networks. The results also show that all GNSS provide good visibility with low elevation angles, whereas with high elevation angles, which might be needed due to natural barriers, the GLONASS and other satellites provides the highest number of visible satellites. Consequently, the mean motion of the study area was found approximately 7–15 cm for horizontal components (X–Y) and 6 cm for vertical components (Ellipsoidal Height) on the eight IGS points in the both poles.

Area and borders of Antarctic and permafrost—A review and synthesis

AbstractThe Antarctic continent is a crucial area for ultimate determination of permafrost extent on Earth, and its solution depends on the theoretical assumptions adopted. In fact, it ranges from 0.022 × 106 to 14 × 106 km2. This level of inaccuracy is unprecedented in the Earth sciences. The novelty of the present study consists in determining the extent of Antarctic permafrost not based exclusively on empirical studies but on universal criteria resulting from the definition of permafrost as the thermal state of the lithosphere, which was applied for the first time to this continent. The area covered by permafrost in Antarctica is ca. 13.9 million km2, that is its entire surface. This result was also made possible due to the first clear determination of the boundaries and area of the continent. The Antarctic area includes (a) rocky subsurface with (b) continental ice‐sheets and (c) shelf glaciers, which, due to their terrigenous origin and belonging to the lithosphere, belongs to the continent in the same way. Antarctica is covered by continuous permafrost, either in a frozen or in a cryotic state. This also significantly influences delimitation of the global extent of permafrost, which can therefore be defined much more accurately. The proposed ice reclassification and its transfer from the hydrosphere to the lithosphere will allow the uniform treatment of ice in the Earth sciences, both on Earth and on other celestial bodies.

60 million years of glaciation in the Transantarctic Mountains

The Antarctic continent reached its current polar location ~83 Ma and became shrouded by ice sheets ~34 Ma, coincident with dramatic global cooling at the Eocene-Oligocene boundary. However, it is not known whether the first Antarctic glaciers formed immediately prior to this or were present significantly earlier. Here we show that mountain glaciers were likely present in the Transantarctic Mountains during the Late Palaeocene (~60–56 Ma) and middle Eocene (~48–40 Ma). Temperate (warm-based) glaciers were prevalent during the Late Eocene (~40–34 Ma) and, in reduced numbers, during the Oligocene (~34–23 Ma), before larger, likely cold-based, ice masses (including ice sheets) dominated. Some temperate mountain glaciers were present during the Miocene Climatic Optimum (~15 Ma), before a widespread switch to cold-based glaciation. Our findings highlight the longevity of glaciation in Antarctica and suggest that glaciers were present even during the Early-Cenozoic greenhouse world.

Temperature and moisture transport during atmospheric blocking patterns around the Antarctic Peninsula

We assess temperature and moisture transport in and around the Antarctic Peninsula (AP) associated with atmospheric blocking over two domains, one located to the west (150–90°W, 50–70°S, Western AP (WAP)) and the other over and to the east (90–30°W, 50–70°S, Eastern AP (EAP)) of the AP. We make use of surface meteorological observations, ERA5 reanalysis data, and a state-of-the-art atmospheric river (AR) database. Observed temperature anomalies indicate that the WAP and EAP blocking patterns are characterized by significant cold and warm anomalies over the AP, respectively, particularly in austral autumn, winter and spring. Consistent with these changes, cold anomalies depicted by ERA5 are associated with the transport of cold and dry air from the Antarctic continent by southerly and southeasterly flow over the eastern flank of the WAP blocking. ERA5 results highlight the importance of blocking days over the EAP domain (largely centered over the Drake Passage) to the occurrence of warm events associated with northerly and northwesterly warm air transport. Significant increases in integrated vapor transport (IVT) and AR frequency are also evident during the EAP blocking, particularly on the windward side of the AP. During the most extreme blocking days in this domain, there exist significant increases in latent and sensible heat fluxes on the windward side of the AP and the Larsen C Ice Shelf, respectively, indicating the contribution of foehn events to warm anomalies, especially in austral autumn and winter. The co-occurrences between landfalling ARs and blocking are found to amplify foehn effect due to higher IVT and associated latent heat condensation compared to blocking days without ARs. We conclude that blocking patterns are important to understand the occurrence of extremely warm events and landfalling ARs in the AP and their potential impacts on the surface cryospheric processes.

Antarctica ice-mass variations on interannual timescale: Coastal Dipole and propagating transports

The target is the non-secular, non-seasonal, interannual ice-mass redistribution over the Antarctica continent, as observed by the satellite mission GRACE (Gravity Recovery and Climate Experiment) for the period from 2002 to 2016. We employ the empirical orthogonal function (EOF) and complex EOF (CEOF) methods on the GRACE monthly time-variable gravity in the form of the mascon data. We find three separate phenomena on different timescales that are hitherto unreported: (i) EOF Mode 1 represents an interannual standing “seesaw” pattern largely concentrates along the coast, which we refer to as the Antarctica Coastal Dipole (ACD), with turnarounds coincident with ENSO events, relative to precipitation anomalies, whereas Mode 2-3 both correlate with the Antarctica Oscillation (AAO); (ii) the leading CEOF Mode shows two different propagating waves, one is the Eastward Propagation (EP) with the periodicity of ∼4.7 years most evident in the East Antarctica, may be induced by the Antarctica Circumpolar Wave; (iii) another is a Westward Propagation (WP) with ∼2 years periodicity in the West Antarctica that mainly travels from the Ronnie Ice Shelf to the Ross Ice Shelf, may relate to AAO.

Heat tolerance of marine ectotherms in a warming Antarctica.

Global warming is affecting the Antarctic continent in complex ways. Because Antarctic organisms are specialized to living in the cold, they are vulnerable to increasing temperatures, although quantitative analyses of this issue are currently lacking. Here we compiled a total of 184 estimates of heat tolerance belonging to 39 marine species and quantified how survival is affected concomitantly by the intensity and duration of thermal stress. Species exhibit thermal limits displaced toward colder temperatures, with contrasting strategies between arthropods and fish that exhibit low tolerance to acute heat challenges, and brachiopods, echinoderms, and molluscs that tend to be more sensitive to chronic exposure. These differences might be associated with mobility. A dynamic mortality model suggests that Antarctic organisms already encounter temperatures that might be physiologically stressful and indicate that these ecological communities are indeed vulnerable to ongoing rising temperatures.

Geographical differences in the diet of Dissostichus mawsoni revealed by metabarcoding

The diet of the Antarctic toothfish (Dissostichus mawsoni) was analyzed using metabarcoding to determine whether spatiotemporal factors are related to its feeding ecology. A diet metabarcoding analysis was conducted for five years from 2016 to 2020 using 1,777 samples collected from two distantly located subareas, 88.3 and 58.4.1. Metabarcoding results revealed 105 prey haplotypes (29 families, 45 genera) in the stomach contents of D. mawsoni, which can serve as valuable genetic information for the accurate identification of piscine species inhabiting the Southern Ocean. Most of the stomach contents of D. mawsoni consisted of fish taxa, comprising 99.61% of read count, which is consistent with other studies indicating that D. mawsoni is piscivorous. The prey compositions were highly different between the two subareas (88.3 and 58.4.1) regardless of the year, indicating that the diet of D. mawsoni strongly reflects the fish assemblages in geographically different habitats. These results strongly suggest that the stomach contents are good ecological indicators for monitoring any changes in the marine ecosystem caused by either the fishery of D. mawsoni, the most voracious piscine predator in its habitat, or environmental changes. In addition, quantitative polymerase chain reaction results of the two most abundant Macrourus prey species of Antarctic toothfish, M. caml and M. whitsoni, showed that the distribution of these two species may be related to the dynamics of gyres, which flow along the Antarctic continent.

Integrated transcriptome and metabolome analyses reveal the adaptation of Antarctic moss Pohlia nutans to drought stress.

Most regions of the Antarctic continent are experiencing increased dryness due to global climate change. Mosses and lichens are the dominant vegetation of the ice-free areas of Antarctica. However, the molecular mechanisms of these Antarctic plants adapting to drought stress are less documented. Here, transcriptome and metabolome analyses were employed to reveal the responses of an Antarctic moss (Pohlia nutans subsp. LIU) to drought stress. We found that drought stress made the gametophytes turn yellow and curled, and enhanced the contents of malondialdehyde and proline, and the activities of antioxidant enzymes. Totally, 2,451 differentially expressed genes (DEGs) were uncovered under drought treatment. The representative DEGs are mainly involved in ROS-scavenging and detoxification, flavonoid metabolism pathway, plant hormone signaling pathway, lipids metabolism pathway, transcription factors and signal-related genes. Meanwhile, a total of 354 differentially changed metabolites (DCMs) were detected in the metabolome analysis. Flavonoids and lipids were the most abundant metabolites and they accounted for 41.53% of the significantly changed metabolites. In addition, integrated transcriptome and metabolome analyses revealed co-expression patterns of flavonoid and long-chain fatty acid biosynthesis genes and their metabolites. Finally, qPCR analysis demonstrated that the expression levels of stress-related genes were significantly increased. These genes included those involved in ABA signaling pathway (NCED3, PP2C, PYL, and SnAK2), jasmonate signaling pathway (AOC, AOS, JAZ, and OPR), flavonoid pathway (CHS, F3’,5’H, F3H, FLS, FNS, and UFGT), antioxidant and detoxifying functions (POD, GSH-Px, Prx and DTX), and transcription factors (ERF and DREB). In summary, we speculated that P. nutans were highly dependent on ABA and jasmonate signaling pathways, ROS scavenging, flavonoids and fatty acid metabolism in response to drought stress. These findings present an important knowledge for assessing the impact of coastal climate change on Antarctic basal plants.

Perchlorate-reducing bacteria from Antarctic marine sediments.

Perchlorate is a contaminant that can persist in groundwater and soil, and is frequently detected in different ecosystems at concentrations relevant to human health. This study isolated and characterised halotolerant bacteria that can potentially perform perchlorate reduction. Bacterial microorganisms were isolated from marine sediments on Deception, Horseshoe and Half Moon Islands of Antarctica. The results of the 16S ribosomal RNA (rRNA) gene sequence analysis indicated that the isolates were phylogenetically related to Psychrobacter cryohalolentis, Psychrobacter urativorans, Idiomarina loihiensis, Psychrobacter nivimaris, Sporosarcina aquimarina and Pseudomonas lactis. The isolates grew at a sodium chloride concentration of up to 30% and a perchlorate concentration of up to 10,000mg/L, which showed their ability to survive in saline conditions and high perchlorate concentrations. Between 21.6 and 40% of perchlorate was degraded by the isolated bacteria. P. cryohalolentis and P. urativorans degraded 30.3% and 32.6% of perchlorate, respectively. I. loihiensis degraded 40% of perchlorate, and P. nivimaris, S. aquimarina and P. lactis degraded 22%, 21.8% and 21.6% of perchlorate, respectively. I. loihiensis had the highest reduction in perchlorate, whereas P. lactis had the lowest reduction. This study is significant as it is the first finding of P. cryohalolentis and. P. lactis on the Antarctic continent. In conclusion, these bacteria isolated from marine sediments on Antarctica offer promising resources for the bioremediation of perchlorate contamination due to their ability to degrade perchlorate, showing their potential use as a biological system to reduce perchlorate in high-salinity ecosystems.