Browsing by Author "Schmit, Amber"

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Biofilms on glacial surfaces: hotspots for biological activity
(2016-06) Smith, Heidi J.; Schmit, Amber; Foster, Rachel A.; Littmann, Sten; Kuypers, Marcel M. M.; Foreman, Christine M.
Glaciers are important constituents in the Earth’s hydrological and carbon cycles, with predicted warming leading to increases in glacial melt and the transport of nutrients to adjacent and downstream aquatic ecosystems. Microbial activity on glacial surfaces has been linked to the biological darkening of cryoconite particles, affecting albedo and increased melt. This phenomenon, however, has only been demonstrated for alpine glaciers and the Greenland Ice Sheet, excluding Antarctica. In this study, we show via confocal laser scanning microscopy that microbial communities on glacial surfaces in Antarctica persist in biofilms. Overall, ~35% of the cryoconite sediment surfaces were covered by biofilm. Nanoscale scale secondary ion mass spectrometry measured significant enrichment of 13C and 15N above background in both Bacteroidetes and filamentous cyanobacteria (i.e., Oscillatoria) when incubated in the presence of 13C–NaHCO3 and 15NH4. This transfer of newly synthesised organic compounds was dependent on the distance of heterotrophic Bacteroidetes from filamentous Oscillatoria. We conclude that the spatial organisation within these biofilms promotes efficient transfer and cycling of nutrients. Further, these results support the hypothesis that biofilm formation leads to the accumulation of organic matter on cryoconite minerals, which could influence the surface albedo of glaciers.
Microbial isolates from Antarctica
(2013-03) Schmit, Amber; Foreman,Christine; Smith, Heidi; Pitts, Betsey
On the surface of glaciers worldwide, there exist aquatic miniature ecosystems in holes in the ice, called cryoconites. Cryoconites form due to preferential melting around low-albedo aeolian particles; which proceed to sink below the surface until finally reaching their equilibrium depth in the ice. Organic windblown sediment collects at the bottom of these water-filled holes. In this sediment there exists a diverse microbial ecosystem that sustains itself despite the extreme environmental characteristics. My work involves the study of the microorganisms within cryoconites. These organisms were obtained from the McMurdo Dry Valleys of Antarctica, and brought back to Montana State University. Here, microbes were isolated on agar plates for further study. When grown on a plate, many of the microbes displayed unique colors of neon pinks, yellows, and oranges. Some of them even fluoresce in UV light. The next stage in learning about these organisms was a basic growth curve test on 48 of the isolates, followed by gram stain tests. Many of the microbes complete the lag, exponential growth, and stationary phases within a few days, while others will take nearly 2 weeks to complete these phases. Most of the isolates were found to be gram negative organisms. It has been found that these microorganisms, when subjected to freeze thaw cycles, overproduce extracellular polysaccharides and create a biofilm. Using the confocal scanning laser microscope, these isolates and their resulting biofilm structures have been imaged. Future studies will continue to focus on imaging these biofilms, as well as imaging the cryoconite granules and associated biofilms that exist on these granules.