Organic carbon transformations in high-Arctic peat soils: key functions and microorganisms

Area of Science:

• Environmental microbiology
• Soil science
• Climate change research

Background:

• Arctic permafrost peatlands store substantial soil organic carbon (SOC).
• These ecosystems are potential sources of greenhouse gases (CH(4) and CO(2)) under climate warming.
• Microbial communities driving SOC breakdown in these soils are poorly understood.

Purpose of the Study:

• Investigate the microbial communities and their genetic repertoire involved in SOC degradation in Arctic peat soils.
• Characterize the metabolic potential for SOC breakdown in the active layer of permafrost peatlands.
• Determine the microbial drivers of greenhouse gas emissions from thawing permafrost.

Main Methods:

• Combined metagenomic and metatranscriptomic analysis of two Arctic peat soil samples.
• Identification of genes encoding plant polymer-degrading enzymes.
• Analysis of microbial community structure and function across soil depths.

Main Results:

• Arctic peat soil microbiotas possess a diverse gene pool for SOC degradation, comparable to temperate and subtropical soils.
• Actinobacteria, Verrucomicrobia, and Bacteroidetes were the dominant phyla involved in SOC degradation.
• Anaerobic pathways and methanogenic archaea increased with peat depth, indicating a shift in microbial lifestyle.
• CH(4)-oxidizing bacteria, closely related to Methylobacter tundripaludum, were the dominant active methanotrophs.

Conclusions:

• Arctic peat soils have the metabolic potential to become significant CO(2) sources due to increased active layer depth and longer growing seasons.
• Future CH(4) emissions from these ecosystems will be critically dependent on the response of methanotrophic bacteria.
• Understanding microbial SOC degradation is crucial for predicting climate change impacts in Arctic regions.