Interactions Between Bacterivorous Nematodes and Bacteria Reduce N₂O Emissions.

Area of Science:

• Soil ecology
• Microbial ecology
• Biogeochemical cycles

Background:

• Trophic interactions in soil micro-food webs, particularly between nematodes and bacteria, influence nitrogen cycling and nitrous oxide (N2O) dynamics.
• The specific impact of nematode-driven alterations in soil bacterial community composition on N2O emissions remains poorly understood.

Purpose of the Study:

• To investigate the role of the bacterial-feeding nematode Protorhabditis in regulating soil microbial communities.
• To determine the effect of nematode activity on soil N2O production and consumption.
• To explore the potential of nematode-bacteria interactions for mitigating greenhouse gas emissions.

Main Methods:

• Microcosm experiments were conducted using soil defaunated and inoculated with the nematode Protorhabditis.
• Bacterial community composition and the abundance of the nosZ gene were analyzed.
• In vitro experiments assessed the impact of Protorhabditis on Bacillus activity and N2O reduction.

Main Results:

• Defaunation, particularly the removal of Protorhabditis, led to increased N2O emissions.
• Protorhabditis inoculation altered bacterial communities, increasing the relative abundance of Bacillus and the nosZ gene.
• In vitro studies showed Protorhabditis enhances N2O reduction by Bacillus through competition suppression and growth factor production.

Conclusions:

• Nematode-bacteria interactions significantly modify soil N2O emissions.
• The nematode Protorhabditis plays a key role in regulating N2O fluxes by influencing bacterial communities.
• Manipulating soil trophic interactions presents a viable strategy for mitigating greenhouse gas emissions.