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A 25‐year set of daily radiosonde data was used to investigate temperature and humidity inversions at Neumayer Station, coastal Dronning Maud Land, Antarctica. For the first time, inversions were studied differentiating between different synoptic conditions and different height levels. It was shown that, generally, inversions occurred on the majority (78%) of the days, with simultaneous occurrence of humidity and temperature inversions being observed on approximately two thirds of all days. Multiple inversions are common in all seasons for cyclonic and noncyclonic conditions, however, typically occur more frequently under cyclonic conditions. The seasonality of inversion occurrence and features, that is, inversion strength, depth and vertical gradients, was analysed statistically. Different formation mechanisms depending on inversion levels and prevailing weather situations are related to typical annual courses of certain inversion features. Winter maxima were found for the features that are mostly connected to the temperature close to the surface, which is mainly a result of the negative energy balance, thus influencing surface‐based inversions. At the second level, both temperature and humidity inversions are often caused by advection of comparably warm and moist air masses related to the passage of cyclones and their frontal systems. Hence, maxima in several inversion features are found in spring and fall, when cyclonic activity is strongest. Monthly mean profiles of humidity and temperature inversions reveal that elevated inversions are often obscured in average profiles due to large variations in inversion height and depth. [ABSTRACT FROM AUTHOR]

Pigments from microorganisms have triggered great interest in the market, mostly by their "natural" appeal, their favorable production conditions, in addition to the potential new chemical structures or naturally overproducing strains. They have been used in: food, feed, dairy, textile, pharmaceutical, and cosmetic industries. The high rate of pigment production in microorganisms recovered from Antarctica in response to selective pressures such as: high UV radiation, low temperatures, and freezing and thawing cycles makes this a unique biome which means that much of its biological heritage cannot be found elsewhere on the planet. This vast arsenal of pigmented molecules has different functions in bacteria and may exhibit different biotechnological activities, such as: extracellular sunscreens, photoprotective function, antimicrobial activity, biodegradability, etc. However, many challenges for the commercial use of these compounds have yet to be overcome, such as: the low stability of natural pigments in cosmetic formulations, the change in color when subjected to pH variations, the low yield and the high costs in their production. This review surveys the different types of natural pigments found in Antarctic bacteria, classifying them according to their chemical structure. Finally, we give an overview of the main pigments that are used commercially today. [ABSTRACT FROM AUTHOR]

In the last decades, efforts to reduce the use of fossil fuels have increased the search for alternative sustainable sources of renewable energy. In this scenario, hydrocarbons derived from fatty acids are among the compounds that have been drawing attention. The intracellular production of hydrocarbons by bacteria derived from cold environments such as the Antarctic continent is currently poorly investigated, as extremophilic microorganisms provide a great range of metabolic capabilities and may represent a key tool in the production of biofuels. The aim of this study was to explore the ability of bacterial cells derived from extreme environments to produce hydrocarbons with potential for further use as biofuels. Seven bacteria isolated from Antarctic samples were evaluated for hydrocarbon production using GC–MS approaches. Two isolates, identified as Arthrobacter livingstonensis 593 and Pseudoalteromonas arctica 628, were able to produce the hydrocarbon undecane (CH3-(CH2)9-CH3) in concentrations of 1.39 mg L−1 and 1.81 mg L−1, respectively. Results from the present work encourage further research focusing on the optimization of hydrocarbon production by the isolates identified as producers, which may be used in further aircraft biofuel production. This is the first report on the production of the undecane compound by bacteria isolated from waterlogged soil and sponge from Antarctica. [ABSTRACT FROM AUTHOR]

Atmospheric rivers (ARs) are an important component of the hydrological cycle linking moisture sources in lower latitudes to the Antarctic surface mass balance. We investigate AR signatures in the atmospheric vertical profiles at the Dronning Maud Land coast, East Antarctica, using regular and extra radiosonde measurements conducted during the Year of Polar Prediction Special Observing Period November 2018 to February 2019. Prominent AR events affecting the locations of Neumayer and Syowa cause a strong increase in specific humidity extending through the mid-troposphere and a strong low-level jet (LLJ). At Neumayer, the peak in the moisture inversion (up to 4 g kg−1) is observed between 800 and 900 hPa, while the LLJ (up to 32 m s−1) is concentrated below 900 hPa. At Syowa the increase in humidity is less pronounced and peaks near the surface, while there is a substantial increase in wind speed (up to 40 m s−1) between 825 and 925 hPa. Moisture transport (MT) within the vertical profile during the ARs attains a maximum of 100 g kg−1 m s−1 at both locations, and is captured by both ERA-Interim and ERA5 reanalysis data at Neumayer, but is strongly underestimated at Syowa. Composites of the enhanced MT events during 2009-19 show that these events represent an extreme state of the lower-tropospheric profile compared to its median values with respect to temperature, humidity, wind speed and, consequently, MT. High temporal- and vertical-resolution radiosonde observations are important for understanding the contribution of these rare events to the total MT towards Antarctica and improving their representation in models. [ABSTRACT FROM AUTHOR]

The Antarctic continent hosts heterogeneous regions, which are in general exposed to extreme conditions, mainly low temperatures. Thus, microorganisms that thrive in this environment are supposed to harbor a metabolic versatility of great biotechnological interest, which includes the production of cold-adapted enzymes. The present study aimed to investigate chitinase production by bacteria isolated from marine and terrestrial samples from the Maritime Antarctica. For this, a collection of 560 bacteria was evaluated. Seventy-three (13%) isolates, belonging to 13 bacterial genera affiliated to Proteobacteria (6), Actinobacteria (4) and Firmicutes (3), were positive in preliminary assays, and twenty strains were further selected based on individual plate assays at 5 and 15 °C. These strains were identified such as Arthrobacter psychrochitiniphilus , Arthrobacter cryoconite and Curtobacterium luteum , all belonging to the phylum Actinobacteria. The best chitinase producer was A. psychrochitiniphilus 492, which showed 43.39 U/L in 80 h of incubation. After optimization of nine independent variables by Plackett-Burman experimental design, followed by a fractional factorial (25−1) and a central composite design (CCD) 23, the best condition for chitinase production was achieved using yeast extract 1.0 g/L, NH 4 NO 3 2.0 g/L, colloidal chitin 5.0% and initial pH 6.0, which allowed an increase of 7.7-fold in chitinase production as compared with the initial condition without optimization. Results gathered herein reinforce the Antarctic environment as a rich source for chitinase prospecting and open perspectives for further optimization strategies aiming future biotechnological application of such molecules in ecologically-friendly and sustainable processes. [Display omitted] • Chitinase was produced mainly by Antarctic bacteria from Arthrobacter and Curtobacterium. • Twenty Antarctic bacteria showed chitinase activity at 5 and 15 °C. • After optimization by experimental design allows an increase of 7.7-fold in the chitinase. • Colloidal chitin and NH 4 NO 3 were the variables that most affected the production of chitinase. [ABSTRACT FROM AUTHOR]

The Antarctic continent is characterized by extreme conditions and encompasses peculiar environments which represent promising habitats for the recovery of well-adapted microorganisms with unique metabolic capabilities. Enzymatic activity combined to salinity and pH tolerance of bacteria that thrive in low temperature environment have attracted attention of researchers in recent years and, as scarce information on that topic is available, the aim of this study was to prospect bacteria isolated from Antarctic samples for extracellular amylase activity and to determine their salinity and pH tolerances. Ninety-one bacteria isolated from Antarctic environmental samples, including marine sponges and invertebrates, sediments and soil biofilm, were screened. Fourty-two isolates were selected as putative amylase producers based on their ability to produce clearing zones in agar plates. Eighty-six and forty-four isolates were able to grow at 5 and 10% NaCl concentrations, respectively. The best enzymatic activities for isolates 226 and 227 were 768.5 U dL−1 (20 °C) and 1410,16 U dL−1 (20 °C), respectively, both influenced by the temperature. All variables assayed showed statistically significant differences for isolates 227 and 226, demonstrating that enzyme activities respond differently to the applied conditions. This is the first report that describes the amylase activity from Carnobacterium and Psychrobacter strains isolated from Antarctic samples. These results encourage subsequent investigations of enzymes produced by microorganisms adapted to low temperatures and high osmolarity conditions, aiming future biotechnological application in pharmaceutical, textile or food industries. Image 1 [ABSTRACT FROM AUTHOR]

To derive paleotemperatures from ice cores, the relationship between stable isotope ratios of precipitation and the condensation temperature at the deposition site is used. However, as only a few records of Antarctic condensation temperature are available, the temperature at the top of the inversion layer has been often used as a surrogate for condensation temperature. A 25-year data set of pressure, temperature, humidity, wind-speed and –direction obtained from 7664 radiosoundings performed at the German Antarctic research station "Neumayer" were used for a detailed study of temperature and humidity inversions during the time period 1993-2017. In particular, inversion strength (depth and lapse rate), frequency and seasonality and the relationship to wind-speed and -direction were investigated. 3-hourly SYNOP data (past and current weather conditions) were employed to distinguish between inversions during clear-weather conditions, which are caused by radiation processes, and advection-type inversions during the passage of cyclones. For the latter, the association with moisture transport was studied, too. It could be shown that humidity and temperature inversions are not necessarily directly related, but could occur at different times and different altitudes. Also multiple inversions were found for both temperature and humidity. These results can be further used to improve the paleoclimatological interpretation of ice cores and to contribute to the progress of numerical atmospheric modeling (e.g. precipitable water estimates) in coastal Antarctic regions. [ABSTRACT FROM AUTHOR]

Sympatry can lead to higher competition under climate change and other environmental pressures, including in South Georgia, Antarctica, where the two most common octopod species, Adelieledone polymorpha and Pareledone turqueti , occur side by side. Since cephalopods are typically elusive animals, the ecology of both species is poorly known. As beaks of cephalopods are recurrently found in top predator's stomachs, we studied the feeding ecology of both octopods through the evaluation of niche overlapping and specific beak adaptations that both species present. A multidisciplinary approach combining carbon (δ13C) and nitrogen (δ15N) stable isotope signatures, mercury (Hg) analysis and biomaterials' engineering techniques was applied to investigate the beaks. An isotopic niche overlap of 95.6% was recorded for the juvenile stages of both octopod species, dropping to 19.2% for the adult stages. Both A. polymorpha and P. turqueti inhabit benthic ecosystems around South Georgia throughout their lifecycles (δ13C: −19.21 ± 1.87‰, mean ± SD for both species) but explore trophic niches partially different during adult life stages (δ15N: 7.01 ± 0.40‰, in A. polymorpha, and 7.84 ± 0.65‰, in P. turqueti). The beaks of A. polymorpha are less dense and significantly less stiff than in P. turqueti. Beaks showed lower mercury concentration relative to muscle (A. polymorpha - beaks: 0.052 ± 0.009 μg g−1, muscle: 0.322 ± 0.088 μg g−1; P. turqueti - beaks: 0.038 ± 0.009 μg g−1; muscle: 0.434 ± 0.128 μg g−1). Overall, both octopods exhibit similar habitats but different trophic niches, related to morphology/function of beaks. The high Hg concentrations in both octopods can have negative consequences on their top predators and may increase under the present climate change context. [ABSTRACT FROM AUTHOR]