Metagenomics and Synchrotron Fourier Transform Infrared Resolved Changes in Carbon and Nitrogen Cycling in an Arctic Tundra
Authors
Neslihan Taş1,2* (ntas@lbl.gov), Nancy Conejo1, Sarah Feng1, Marla DeKlotz1, Hoi-Ying Holman1, Colleen Iversen2
Institutions
1Lawrence Berkeley National Laboratory, Berkeley, CA; 2Oak Ridge National Laboratory, Oak Ridge, TN
URLs
Abstract
This project uses state-of-the-art sequencing and imaging technologies to resolve complex interactions governing biochemical cycles in tundra biomes to inform efforts to decipher Arctic carbon and nitrogen cycling. Arctic soils are crucial in climate change research due to potential rapid microbial mineralization and increased greenhouse gas (GHG) emissions under rising temperatures. The diverse microbial habitats in these soils, shaped by various landscape features, show varying responses to warming, but the seasonal impact on GHG production remains unclear. Between 2011 and 2022, the team conducted multiple sampling campaigns to collect active layer soils from the polygonal Arctic tundra at the Barrow Environmental Observatory. Researchers analyzed these soils’ chemical and biological properties and performed lab-scale soil incubations to test the impact of warmer winters on GHG emissions. To better understand the microbial communities in these soils, the team extracted and sequenced the whole community DNA and reconstructed prokaryotic and viral genomes. In addition, researchers analyzed the soil biochemistry via synchrotron Fourier transform infrared spectral imaging at the Berkeley Infrared Structural Biology beamline of the Advanced Light Source to link soil chemistry and microbial communities. The team discovered that the microbiomes are organized by topography, significantly influencing the distribution of genes linked to GHG emissions, with GHG production potential varying across different polygons. At the site, limited pools of butyrate, lactate, formate, and acetate were observed with carbon chemistry predominantly consisting of lignocellulose and chitin where microbes were mostly found.
Marginal differences in the distribution of carbon compounds between organic and mineral layers were detected, paralleling genomic data observations. Especially in wetter portions of the landscape, significantly higher carbon dioxide fluxes were detected after a warm winter. The project’s research highlights that landscape topography primarily determines microbial functions, and integrating these with geochemistry and GHG fluxes offers insights into Arctic soil biogeochemical cycles.