Unlocking bacterial potential to reduce farmland N₂O emissions

Area of Science:

• Agricultural Science
• Environmental Microbiology
• Climate Change Mitigation

Background:

• Agricultural soils are major sources of nitrous oxide (N₂O), a potent greenhouse gas, with limited mitigation strategies available.
• Microbial N₂O production is widespread, but biological N₂O consumption relies on the enzyme NosZ, which converts N₂O to N₂.
• Enhancing NosZ activity in soil microbiomes to reduce N₂O emissions is considered a significant bioengineering challenge.

Purpose of the Study:

• To develop and evaluate a novel technology for reducing soil N₂O emissions using N₂O-respiring bacteria.
• To analyze the N₂O reduction biokinetics, soil survival, and field emission reduction efficacy of Cloacibacterium sp. CB-01.
• To assess the potential of this approach for large-scale N₂O emission reduction in European agriculture.

Main Methods:

• Cultivation of Cloacibacterium sp. CB-01 on organic waste (biogas production residue).
• Application of the bacterial-laden waste to agricultural soils in field experiments.
• Measurement of N₂O emissions and assessment of bacterial survival and activity in different soil types.

Main Results:

• Fertilization with CB-01 grown on biogas waste reduced N₂O emissions by 50-95% across various soil types.
• The effectiveness of CB-01 was attributed to its persistence in soil rather than superior N₂O reduction kinetics.
• Extrapolation to European agriculture suggests potential reductions of 5-20% in national anthropogenic N₂O emissions.

Conclusions:

• The application of specific N₂O-respiring bacteria, like Cloacibacterium sp. CB-01, via organic waste offers a viable strategy for mitigating soil N₂O emissions.
• The bacteria's tenacity in soil is key to its long-lasting impact on reducing greenhouse gas emissions.
• This method presents a cost-effective avenue for reducing N₂O emissions, addressing a critical gap in current mitigation options.