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Cryoconite holes (cylindrical melt-holes on the glacier surface) are important hydrological and biological systems within glacial environments that support diverse microbial communities and biogeochemical processes. This study describes retrievable heterotrophic microbes in cryoconite hole water from three geographically distinct sites in Antarctica, and a Himalayan glacier, along with their potential to degrade organic compounds found in these environments. Microcosm experiments (22 days) show that 13–60% of the dissolved organic carbon in the water within cryoconite holes is bio-available to resident microbes. Biodegradation tests of organic compounds such as lactate, acetate, formate, propionate and oxalate that are present in cryoconite hole water show that microbes have good potential to metabolize the compounds tested. Substrate utilization tests on Biolog Ecoplate show that microbial communities in the Himalayan samples are able to oxidize a diverse array of organic substrates including carbohydrates, carboxylic acids, amino acids, amines/amides and polymers, while Antarctic communities generally utilized complex polymers. In addition, as determined by the extracellular enzyme activities, majority of the microbes (82%, total of 355) isolated in this study (Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria and Basidiomycota) had ability to degrade a variety of compounds such as proteins, lipids, carbohydrates, cellulose and lignin that are documented to be present within cryoconite holes. Thus, microbial communities have good potential to metabolize organic compounds found in the cryoconite hole environment, thereby influencing the water chemistry in these holes. Moreover, microbes exported downstream during melting and flushing of cryoconite holes may participate in carbon cycling processes in recipient ecosystems. [ABSTRACT FROM AUTHOR]

Spatial trends of acetate (Ac − ) and formate (Fo − ) were determined in surface snow samples along a coastal-inland transect (180 km) in the ice cap region at Princess Elizabeth Land and along a coastal transect in the Amery Ice Shelf (130 km), East Antarctica. Variations in both Ac − and Fo − seem to be unrelated to the acidity of snow. Ionic balance determined for the snow samples indicate the availability of HNO 3 that could undergo photolysis to produce hydroxyl radical ( OH), one of the major reactants involved in oxidation reactions with organic matter. The strong positive correlations between Ac − and NO 3 − in snow from both regions indicate that NO 3 − mediated OH-oxidation of organic compounds in snow could be an important source of Ac − within the snowpack. On the other hand, negative correlation between Fo − and NO 3 − might indicate that sources other than OH-oxidation of organic matter may be dominant in the case of Fo − . Higher Ac − concentrations in the ice cap compared to the ice shelf correspond with long-range transport of biomass burning emissions to the ice cap region. Interaction of Ac − and Fo − with alkaline minerals could lead to their stability in the snowpack and minimize their loss from the snow surface. Resident microbial communities could also influence the budget of the carboxylic acids in snow. [ABSTRACT FROM AUTHOR]

Snow ecosystems represent a large part of the Earth's biosphere and harbour diverse microbial communities. Despite our increased knowledge of snow microbial communities, the question remains as to their functional potential, particularly with respect to their role in adapting to and modifying the specific snow environment. In this work, we investigated the diversity and functional capabilities of microorganisms from 3 regions of East Antarctica, with respect to compounds present in snow and tested whether their functional signature reflected the snow environment. A diverse assemblage of bacteria (Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, Deinococcus-Thermus, Planctomycetes, Verrucomicrobia), archaea (Euryarchaeota), and eukarya (Basidiomycota, Ascomycota, Cryptomycota and Rhizaria) were detected through culture-dependent and −independent methods. Although microbial communities observed in the three snow samples were distinctly different, all isolates tested produced one or more of the following enzymes: lipase, protease, amylase, β-galactosidase, cellulase, and/or lignin modifying enzyme. This indicates that the snow pack microbes have the capacity to degrade organic compounds found in Antarctic snow (proteins, lipids, carbohydrates, lignin), thus highlighting their potential to be involved in snow chemistry. [ABSTRACT FROM AUTHOR]

Abstract: Microbiological studies of polar ice at different depths may provide important comparisons, as they preserve records of microbial cells and past climate. In this study, we examined bacterial abundance, diversity and glaciochemical composition from three depths of an ice core from coastal Dronning Maud Land, East Antarctica. Higher bacterial abundance corresponded with high in situ sea-salt Na+ and dust concentration, suggesting that bacteria might have been transported and deposited into ice along with dust particles and marine aerosols. Fourteen bacterial isolates belonging to the genera Methylobacterium, Brevundimonas, Paenibacillus, Bacillus and Micrococcus were retrieved. Frequent isolation of similar bacterial genera from different cold environments suggests that they possess features that enable survival and metabolism for extended periods of time at sub-zero temperatures. The highest number and diversity of recoverable bacteria was obtained from 49m depth corresponding to 1926 AD and consisted of bacteria from 4 different genera whereas at 11m (1989 AD) and 33m (1953 AD) samples only species belonging to the genera Bacillus was recovered. Among the Bacillus species, Bacillus aryabhattai which has been reported only from the upper stratosphere, was isolated and is the first record from the Earth''s surface. Methylobacterium was the most dominant genera at 49m depth and its prevalence is attributable to a combination of high in situ methanesulfonate concentration, specialized metabolism and environmental hardiness of Methylobacterium. Some of the isolated bacteria were found to respire and grow using methanesulfonate, suggesting that they may utilize this substrate to sustain growth in ice. In addition, NO3 − (2.93–3.69μM), NH4 + (1.45–3.90μM) and PO4 3− (0.01–0.75μM) present in the ice could be potential sources fueling bacterial metabolism in this environment. It could be deduced from the study that variation in bacterial abundance and diversity was probably associated with the prevailing in situ conditions in ice. [Copyright &y& Elsevier]