Project description:Glacier ice algae of the streptophyte genus Ancylonema live on glaciers globally, including the Greenland Ice Sheet. Each summer these algae bloom despite freezing temperatures, low nutrient availability, and very high light intensities. These algae also survive continual darkness during polar night. However, little is known about the cellular mechanisms underpinning glacier ice algae resistance and adaptation to high light or how they survive during dark periods. To address this knowledge gap, we evaluated the response of Ancylonema-dominated samples from the Greenland Ice Sheet to light and dark conditions over a 12-day incubation experiment using combined multi-omics analyses: amplicon sequencing, metatranscriptomics, and metaproteomics.
Project description:Because of severe abiotic limitations, Antarctic soils represent simplified ecosystems, where microorganisms are the principle drivers of nutrient cycling. This relative simplicity makes these ecosystems particularly vulnerable to perturbations, like global warming, and the Antarctic Peninsula is among the most rapidly warming regions on the planet. However, the consequences of the ongoing warming of Antarctica on microorganisms and the processes they mediate are unknown. Here, using 16S rRNA gene pyrosequencing and qPCR, we report a number of highly consistent changes in microbial community structure and abundance across very disparate sub-Antarctic and Antarctic environments following three years of experimental field warming (+ 0.5-2°C). Specifically, we found significant increases in the abundance of fungi and bacteria and in the Alphaproteobacteria-to-Acidobacteria ratio. These alterations were linked to a significant increase in soil respiration. Furthermore, the shifts toward generalist or opportunistic bacterial communities following warming weakened the linkage between bacterial diversity and functional diversity. Warming also increased the abundance of some organisms related to the N-cycle, detected as an increase in the relative abundance of nitrogenase genes via GeoChip microarray analyses. Our results demonstrate that soil microorganisms across a range of sub-Antarctic and Antarctic environments can respond consistently and rapidly to increasing temperatures, thereby potentially disrupting soil functioning.