Understanding the effects of nitrogen amendments on Antarctic soil microbial community resilience, resistance and redundancy
Bhika Kooverjee, B .• de_Scally, S .• Valverde, A., Cowan, DA .• Makhalanyane, T.P.
Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, South Africa [email protected]
A rise in average annual temperatures is leading to the melting of glacial and buried ice in some regions of the Antarctic continent [1]. Increased moisture has led to the mobilization of nutrients [2], which could have an impact on the cycling of carbon and nitrogen in Antarctic Dry Valley soils.
These soils are hyperarid and low in organic nutrients such as carbon (C) and nitrogen (N) [3]. The mobilization of these nutrients from deep soils to surface communities as a result of permafrost melting [4] may have simplex consequences on microbial activity and associated nutrient dynamics mediated by soil microorganisms. However, the effects of increased N levels on altering soil biogeochemical cycling remain unclear. A microcosm experiment will be used to assess the impacts of N amendments on Antarctic soil microbial communities, at both structural and functional levels.
Surface soils from the Antarctic Dry Valleys will be used in the microcosms. Four treatments will be applied to the microcosms, with different substrates, namely; glucose, ammonium chloride, glycine, and sterile water. Microcosms will be monitored over a period of 60 days and soil will be destructively sampled at five pre-defined time points; 0, 15, 30, 45 and 60 days post inoculation.
Metagenomic DNA will be extracted at each time point and 165 rRNA genes will be sequenced on an lllumina MiSeq platform and analysed using QIIME. Additionally, enzymatic assays will be performed to determine the heterotrophic activity of soils in response to the N amendments. These include the use of cellulase, phosphatase and aminopeptidase enzymes. Together this information will provide valuable insights into the effects of increased N levels and water availability on Antarctic soil community composition and activity.
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