Bacterial N₂O mitigation potential in soil-based systems and liquid cultures: a comprehensive meta-analysis

Area of Science:

• Agricultural Science
• Environmental Science
• Microbiology

Background:

• Nitrous oxide (N₂O) is a major greenhouse gas contributing to climate change.
• Biological mitigation of N₂O is crucial for climate change mitigation.
• Bacterial inoculation offers a promising strategy for N₂O mitigation in agriculture.

Purpose of the Study:

• To quantitatively assess the regulatory effects of bacterial inoculation on N₂O mitigation.
• To investigate the environment-specificity of N₂O mitigation strategies.
• To explore molecular mechanisms underlying N₂O biological mitigation.

Main Methods:

• Meta-analysis of 257 data points from 34 independent studies.
• Comparative analysis of soil-based and liquid culture incubation systems.
• Functional gene analysis and phylogenetic characterization.

Main Results:

• Bacterial inoculation significantly reduced N₂O emissions, with higher mitigation in liquid cultures (68.3%) than soil systems (42.9%).
• Mitigation effectiveness is environment-specific, influenced by factors like oxygen availability, pH, and cultivation duration.
• Denitrification pathway, alongside dissimilatory nitrate reduction and nitrogen fixation, likely plays a core role in N₂O mitigation.

Conclusions:

• Bacterial inoculation is an effective N₂O mitigation strategy, but its success is strongly dependent on the environmental system.
• Liquid culture systems show superior N₂O mitigation potential compared to soil-based systems.
• Identification of key genera like *Bradyrhizobium* (soil) and *Azospira* (liquid) provides guidance for developing tailored microbial mitigation technologies.