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Although the Antarctic lakes are of great importance for the climate and the carbon cycle, the lithological influences on the input of elements that are necessary for phytoplankton in lakes have so far been insufficiently investigated. To address this issue, we analyzed phytoplankton cell concentrations and chemical compositions of water samples from lakes, ponds and a stream on Fildes and Ardley Islands of King George Island in the South Shetland Archipelago. Furthermore, lake sediments, as well as soil and rock samples collected from the littoral zone were analyzed for their mineralogical/petrographic composition and pollutant contents of polycyclic aromatic hydrocarbons (PAHs). In addition, leaching experiments were carried out to with the lithologic samples to investigate the possible changes in pH, alkalinity, macronutrients (N, P, Si), micronutrients (e.g. Fe, Zn, Cu, Mn), anions (S, F, Br), and other cations (e.g. Na, K, Mg, Ca, Al, Ti, V, Cr, Co, Ni, As, Se, Pb, Sb, Mo, Ag, Cd, Sn, Ba, Tl, B). Our results showed that phytoplankton levels varied between 15 and 206 cells/mL. Chlorophyll-a concentrations showed high correlations with NH 4 , NO 3 . The low levels of PO 4 (<0.001 mg/L) indicated a possible P-limitation in the studied lakes. The composition of rock samples ranged from basalt to trachybasalt with variable major oxide (e.g. SiO 2 , Na 2 O and K 2 O) contents and consist mainly quartz, albite, calcite, dolomite and zeolite minerals. The concentrations of total PAHs were below the toxic threshold levels (9.55-131.25 ng g -1 dw). Leaching experiments with lithologic samples indicated major increase in pH (up to 9.77 ± 0.02) and nutrients, especially PO 4 (1.03 ± 0.04 mg/L), indicating a strong P-fertilization impact in increased melting scenarios. Whereas, toxic elements such as Pb, Cu, Cd, Al and As were also released from the lithology, which may reduce the phytoplankton growth., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: N. Olgun reports financial support was provided by Technological Research Council of Türkiye. N. Olgun reports a relationship with Technological Research Council of Türkiye that includes: funding grants., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Methane-cycling is becoming more important in high-latitude ecosystems as global warming makes permafrost organic carbon increasingly available. We explored 387 samples from three high-latitudes regions (Siberia, Alaska and Patagonia) focusing on mineral/organic soils (wetlands, peatlands, forest), lake/pond sediment and water. Physicochemical, climatic and geographic variables were integrated with 16S rDNA amplicon sequences to determine the structure of the overall microbial communities and of specific methanogenic and methanotrophic guilds. Physicochemistry (especially pH) explained the largest proportion of variation in guild composition, confirming species sorting (i.e., environmental filtering) as a key mechanism in microbial assembly. Geographic distance impacted more strongly beta diversity for (i) methanogens and methanotrophs than the overall prokaryotes and, (ii) the sediment habitat, suggesting that dispersal limitation contributed to shape the communities of methane-cycling microorganisms. Bioindicator taxa characterising different ecological niches (i.e., specific combinations of geographic, climatic and physicochemical variables) were identified, highlighting the importance of Methanoregula as generalist methanogens. Methylocystis and Methylocapsa were key methanotrophs in low pH niches while Methylobacter and Methylomonadaceae in neutral environments. This work gives insight into the present and projected distribution of methane-cycling microbes at high latitudes under climate change predictions, which is crucial for constraining their impact on greenhouse gas budgets., (© 2023 The Authors. Environmental Microbiology published by Applied Microbiology International and John Wiley & Sons Ltd.)

The COVID-19 pandemic has caused an unprecedented health and economic crisis, highlighting the importance of developing new molecular tools to monitor and detect SARS-CoV-2. Hence, this study proposed to employ the carrageenan extracted from Gigartina skottsbergii algae as a probe for SARS-CoV-2 virus binding capacity and potential use in molecular methods. G. skottsbergii specimens were collected in the Chilean subantarctic ecoregion, and the carrageenan was extracted -using a modified version of Webber's method-, characterized, and quantified. After 24 h of incubation with an inactivated viral suspension, the carrageenan's capacity to bind SARS-CoV-2 was tested. The probe-bound viral RNA was quantified using the reverse transcription and reverse transcription loop-mediated isothermal amplification (RT-LAMP) methods. Our findings showed that carrageenan extraction from seaweed has a similar spectrum to commercial carrageenan, achieving an excellent proportion of binding to SARS-CoV-2, with a yield of 8.3%. Viral RNA was also detected in the RT-LAMP assay. This study shows, for the first time, the binding capacity of carrageenan extracted from G. skottsbergii , which proved to be a low-cost and highly efficient method of binding to SARS-CoV-2 viral particles.

Freshwater ecosystems are important contributors to the global greenhouse gas budget and a comprehensive assessment of their role in the context of global warming is essential. Despite many reports on freshwater ecosystems, relatively little attention has been given so far to those located in the southern hemisphere and our current knowledge is particularly poor regarding the methane cycle in non-perennially glaciated lakes of the maritime Antarctica. We conducted a high-resolution study of the methane and carbon dioxide cycle in a lake of the Fildes Peninsula, King George Island (Lat. 62°S), and a succinct characterization of 10 additional lakes and ponds of the region. The study, done during the ice-free and the ice-seasons, included methane and carbon dioxide exchanges with the atmosphere (both from water and surrounding soils) and the dissolved concentration of these two gases throughout the water column. This characterization was complemented with an ex-situ analysis of the microbial activities involved in the methane cycle, including methanotrophic and methanogenic activities as well as the methane-related marker gene abundance, in water, sediments and surrounding soils. The results showed that, over an annual cycle, the freshwater ecosystems of the region are dominantly autotrophic and that, despite low but omnipresent atmospheric methane emissions, they act as greenhouse gas sinks., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

High latitudes are experiencing intense ecosystem changes with climate warming. The underlying methane (CH 4 ) cycling dynamics remain unresolved, despite its crucial climatic feedback. Atmospheric CH 4 emissions are heterogeneous, resulting from local geochemical drivers, global climatic factors, and microbial production/consumption balance. Holistic studies are mandatory to capture CH 4 cycling complexity. Here, we report a large set of integrated microbial and biogeochemical data from 387 samples, using a concerted sampling strategy and experimental protocols. The study followed international standards to ensure inter-comparisons of data amongst three high-latitude regions: Alaska, Siberia, and Patagonia. The dataset encompasses different representative environmental features (e.g. lake, wetland, tundra, forest soil) of these high-latitude sites and their respective heterogeneity (e.g. characteristic microtopographic patterns). The data included physicochemical parameters, greenhouse gas concentrations and emissions, organic matter characterization, trace elements and nutrients, isotopes, microbial quantification and composition. This dataset addresses the need for a robust physicochemical framework to conduct and contextualize future research on the interactions between climate change, biogeochemical cycles and microbial communities at high-latitudes., (© 2022. The Author(s).)

Freshwater ecosystems are responsible for an important part of the methane (CH 4 ) emissions which are likely to change with global warming. This study aims to evaluate temperature-induced (from 5 to 20 °C) changes on microbial community structure and methanogenic pathways in five sub-Antarctic lake sediments from Magallanes strait to Cape Horn, Chile. We combined in situ CH 4 flux measurements, CH 4 production rates (MPRs), gene abundance quantification and microbial community structure analysis (metabarcoding of the 16S rRNA gene). Under unamended conditions, a temperature increase of 5 °C doubled MPR while microbial community structure was not affected. Stimulation of methanogenesis by methanogenic precursors as acetate and H 2 /CO 2 , resulted in an increase of MPRs up to 127-fold and 19-fold, respectively, as well as an enrichment of mcrA-carriers strikingly stronger under acetate amendment. At low temperatures, H 2 /CO 2 -derived MPRs were considerably lower (down to 160-fold lower) than the acetate-derived MPRs, but the contribution of hydrogenotrophic methanogenesis increased with temperature. Temperature dependence of MPRs was significantly higher in incubations spiked with H 2 /CO 2 (c. 1.9 eV) compared to incubations spiked with acetate or unamended (c. 0.8 eV). Temperature was not found to shape the total microbial community structure, that rather exhibited a site-specific variability among the studied lakes. However, the methanogenic archaeal community structure was driven by amended methanogenic precursors with a dominance of Methanobacterium in H 2 /CO 2 -based incubations and Methanosarcina in acetate-based incubations. We also suggested the importance of acetogenic H 2 -production outcompeting hydrogenotrohic methanogenesis especially at low temperatures, further supported by homoacetogen proportion in the microcosm communities. The combination of in situ-, and laboratory-based measurements and molecular approaches indicates that the hydrogenotrophic pathway may become more important with increasing temperatures than the acetoclastic pathway. In a continuously warming environment driven by climate change, such issues are crucial and may receive more attention., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

This research focused on the development of carrageenan based biodegradable films incorporated with olive leaves extract (OLE). OLE microbial inhibition and its total phenolics (TP) were evaluated. Carrageenan films were produced by casting technique and were characterized by thickness, water vapor permeability (WVP), color, mechanical properties, and infrared spectroscopy. In order to apply as lamb meat packaging, the antimicrobial effect of the films was investigated. Results showed that OLE inhibited E. coli growth and presented excellent TP (41.40 mg GAE /g). Thicknesses of the film with OLE (CAR-OLE) were approximately 28% higher than film without OLE. Addition of OLE reduced the WVP by approximately 54%. CAR-OLE was less resistant to breakage and more flexible showing darker color. FTIR showed interaction of carrageenan with OLE. Results revealed that CAR-OLE promoted 167-fold reduction in initial count of aerobic mesophiles indicating shelf-life extension of lamb meat and promising use as antimicrobial food packaging., (© 2020 The Authors. Food Science & Nutrition published by Wiley Periodicals, Inc.)

It is commonly assumed that methane (CH 4 ) released by lakes into the atmosphere is mainly produced in anoxic sediment and transported by diffusion or ebullition through the water column to the surface of the lake. In contrast to that prevailing idea, it has been gradually established that the epilimnetic CH 4 does not originate exclusively from sediments but is also locally produced or laterally transported from the littoral zone. Therefore, CH 4 cycling in the epilimnion and the hypolimnion might not be as closely linked as previously thought. We utilized a high-resolution method used to determine dissolved CH 4 concentration to analyze a Siberian lake in which epilimnetic and hypolimnetic CH 4 cycles were fully segregated by a section of the water column where CH 4 was not detected. This layer, with no detected CH 4 , was well below the oxycline and the photic zone and thus assumed to be anaerobic. However, on the basis of a diffusion-reaction model, molecular biology, and stable isotope analyses, we determined that this layer takes up all the CH 4 produced in the sediments and the deepest section of the hypolimnion. We concluded that there was no CH 4 exchange between the hypolimnion (dominated by methanotrophy and methanogenesis) and the epilimnion (dominated by methane lateral transport and/or oxic production), resulting in a vertically segregated lake internal CH 4 cycle.

The sub-Antarctic Magellanic ecoregion is a part of the world where ecosystems have been understudied and where the CH 4 cycling and emissions in lakes has not ever been reported. To fill that knowledge gap, a lake and a reservoir located at 53°S were selected and studied during three campaigns equally distributed over one year. Among the parameters measured were CH 4 and CO 2 emissions, as well their dissolved concentrations in the water column, which were determined with high spatial resolution. No ebullition was observed and the CH 4 flux ranged from 0.0094 to 4.47mmolm -2 d -1 while the CO 2 flux ranged from -22.95 to 35.68mmolm -2 d -1 . Dissolved CH 4 concentrations varied over more than four orders of magnitude (0.025-128.75μmolL -1 ), and the dissolved carbon dioxide ranged from below the detection limit of our method (i.e., 0.15μmolL -1 ) to 379.09μmolL -1 . The high spatial resolution of the methods used enabled the construction of bathymetric maps, surface contour maps of CH 4 and CO 2 fluxes, and transect contour maps of dissolved oxygen, temperature, and dissolved greenhouse gases. Overall, both lakes were net greenhouse gas producers and were not significantly different from temperate lakes located at a similar northern latitudes (53°N), except that ebullition was never observed in the studied sub-Antarctic lakes., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Escherichia coli bacteria with extended-spectrum β-lactamase (ESBL) type CTX-M resistance were isolated from water samples collected close to research stations in Antarctica. The isolates had bla(CTX-M-1) and bla(CTX-M-15) genotypes and sequence types (ST) indicative of a human-associated origin. This is the first record of ESBL-producing enterobacteria from Antarctica.

Samples of four different species of seaweed were collected monthly between October 2000 and March 2001 from the coast of the Strait of Magellan, Chile to establish baseline levels of trace metals (silver, total mercury, nickel, lead, antimony, vanadium and zinc) and to compare the accumulation capacity among species. The algae included in the study were Adenocystis utricularis (n=15); Enteromorpha sp. (n=11), Mazzaella laminarioides (n=12) and Porphyra columbina (n=6). The concentration range of each metal in microg g(-1) dry weight varied as follows: Ag=ND-0.3, Hg=ND-0.02, Ni=ND-12.6, Pb = ND-11.2, Sb=ND-1.97, V=ND-11.34 and Zn=14.10-79. Results showed that levels of Ag, Hg, Ni, Pb, Sb, V and Zn for all species were similar to those found in other studies for non-contaminated areas with very little influence from anthropogenic activity. Also among the four species studied macroalgae Enteromorpha sp. had the highest capacity for metal accumulation and could therefore be considered as a biomonitor for future studies in the area.

The concentrations of manganese, selenium, nickel and cadmium were determined in 112 samples of molluscs belonging to mussels (Mytilus chilensis, n = 47) and limpets (Nacella deaurata, n = 65), which were collected from the coastline of the Magellan Strait, Chile. Four (6.2%) samples of limpets exceeded the maximum limits for cadmium established in Europe. Limpets showed higher mean manganese, nickel and cadmium concentrations than mussels, whilst the mean selenium concentration in mussels was higher. The consumption of one serving (100 g) of molluscs represents a considerable contribution to the dietary daily intake of selenium, and limpets make a significant contribution to the manganese and cadmium intakes. The sampling zone influenced the trace element concentrations, and different uptakes were observed between the mollusc species.

Chemical fingerprinting approach to environmental assessment is illustrated in the evaluation of marine oil pollution in the coasts using two limpet species as bioindicator organisms, and based on profiles and concentrations of n-alkanes and aromatic hydrocarbons in their tissues. Accidental and chronic releases of hydrocarbons can contaminate the marine environment of the Canary Islands not only because of their geographical situation but also because of the very dense tanker traffic around. This situation affects coastal areas, fishing activities, tourism resort, etc. Concentrations of n-alkanes and aromatic hydrocarbons (polycyclic aromatic hydrocarbons and methyl-polycyclic aromatic hydrocarbons) in the soft tissues of the marine intertidal and subtidal limpets, Patella crenata and Patella ullysiponensis aspera, were evaluated. Limpet samples were collected at monthly intervals, at three locations on the southeast coast of Tenerife over a 3-year period (1991-93). Levels of hydrocarbons found in limpets are similar to concentrations found in unpolluted areas around the world. From application of principal component analysis, the interpretation of variable loading plots gives information on variable correlation and can be used to distinguish among potential sources of pollution and the ability of studied molluscs to be used as bioindicator organisms.

The hydrocarbons contents (n-alkanes, polycyclic aromatic hydrocarbons) were determined in the sea urchin Arbacia lixula. Multivariate data analysis as principal component analysis, factor analysis and, cluster analysis were applied to elucidate sources of pollution. PCA and FA were performed to establish the relationships between variables (hydrocarbons), samples (sea urchin) and sources of pollution.