Guanidine as a Key Substrate in Reducing N₂O Emissions through Comammox Bacteria
MICROBIOLOGY
8/15/2024
Comammox (complete ammonia oxidizers) are a group of microorganisms capable of directly converting ammonia (NH₃) into nitrate (NO₃⁻) through the nitrification process. Known as "green nitrifiers," comammox produce minimal amounts of nitrous oxide (N₂O) during this process, making them crucial for reducing greenhouse gas emissions. A study published in Nature in August 2024 by researchers from the University of Vienna confirmed that one comammox bacterium, Nitrospira inopinata, can grow using guanidine as its sole energy and nitrogen source. This is the first discovery showing that a microorganism can thrive with guanidine as its only substrate. The study also revealed that guanidine is an essential substrate in environmental nitrification, as confirmed through proteomic analysis and incubation experiments involving comammox and common microbiota in agricultural soils and wastewater. This finding provides strong evidence that adding guanidine could effectively reduce N₂O emissions in agricultural lands, the largest contributors to N₂O emissions, by enriching comammox populations and enhancing the isolation of other comammox microorganisms in the future by using guanidine as a key growth substrate.
