Flavobacteria consume nitrous oxide produced by partial denitrifiers in coastal sediments

Area of Science:

• Marine microbial ecology
• Biogeochemical cycles
• Greenhouse gas emissions

Background:

• Oceans contribute significantly to global nitrous oxide (N2O) emissions, especially in nutrient-polluted coastal zones.
• Permeable sediments are widespread and increasingly impacted by nutrient pollution, yet microbial N2O cycling is poorly understood.

Purpose of the Study:

• To investigate microbial N2O production and consumption in permeable coastal sediments.
• To identify key microbes and metabolic pathways involved in N2O cycling.
• To assess the role of N2O reducers in regulating emissions.

Main Methods:

• Environmental measurements and bacterial cultivation.
• Genomic analyses, including metagenomics and isolate genome sequencing.
• Metabolic reconstruction and kinetic profiling of N2O reduction.

Main Results:

• Diverse bacteria were found to produce N2O via incomplete denitrification.
• Highly abundant Flavobacteriaceae (clade II N2O reducers) were identified.
• Both isolates and sediment communities showed low affinity for N2O reduction, yet significant consumption was observed.

Conclusions:

• Specialized microbial communities in permeable sediments actively consume N2O, limiting its accumulation and release.
• These microbial processes are crucial for regulating N2O cycling under nutrient pollution.
• Findings highlight the importance of microbial N2O reduction in coastal biogeochemistry.