Multi-omics reveals nitrogen dynamics associated with soil microbial blooms during snowmelt

Area of Science:

• Environmental Microbiology
• Biogeochemistry
• Ecology

Background:

• Soil microbial communities drive nitrogen cycling, influencing ecosystem function.
• Snowmelt dynamics significantly impact soil nitrogen availability and export in high-elevation regions.
• Global climate change is altering snowpack, necessitating a better understanding of soil nitrogen processes.

Purpose of the Study:

• To elucidate the microbial mechanisms governing nitrogen cycling during snowmelt in high-elevation watersheds.
• To identify key microbial players and their functional roles in nitrogen transformations.
• To predict soil nitrogen dynamics under declining snowpack conditions.

Main Methods:

• Integration of genome-resolved metagenomics, metatranscriptomics, and metabolomics.
• Analysis of soil microbial communities and their nitrogen cycling gene expression.
• Characterization of dissolved organic nitrogen molecular properties and transformations.

Main Results:

• Distinct soil microorganisms were identified with unique nitrogen cycling capacities during snowmelt.
• Degradation/recycling of microbial biomass supplied nitrogen for biosynthesis during bloom.
• Winter-adapted Bradyrhizobia spp. were key in anaerobic amino acid oxidation and denitrification.
• Spring-adapted Nitrososphaerales drove a nitrate pulse, with significant nitrate retention potential via dissimilatory nitrate reduction to ammonia (DNRA).

Conclusions:

• Microbial biomass dynamics and specific microbial groups critically regulate nitrogen cycling during snowmelt.
• Understanding these microbial processes is crucial for predicting nitrogen export in snow-dominated ecosystems facing climate change.
• The study provides insights into microbial N cycling in sensitive high-elevation environments.