Dependency-competition tradeoffs structure microbial niches and nitrogen cycling

Area of Science:

• Marine microbial ecology
• Biogeochemical cycles
• Biogeochemical modeling

Background:

• The marine nitrogen cycle is crucial for regulating nutrient availability and greenhouse gas emissions.
• Anoxic microbial communities, primarily through denitrification and anammox, drive nitrogen loss and nitrous oxide ([Formula: see text]) production.
• The interplay of competition and resource dependencies among these microbes is not fully understood.

Purpose of the Study:

• To investigate how microbial dependencies and competition shape ecological niches and nitrogen loss pathways.
• To explore the impact of varying organic matter (OM) and nitrate supply on microbial interactions and biogeochemical fluxes.
• To identify conditions favoring nitrous oxide ([Formula: see text]) accumulation.

Main Methods:

• Development of a trait-based consumer-resource framework.
• Analysis of microbial interactions under varying organic matter and nitrate supply conditions.
• Identification of equilibrium coexistence regions and threshold regimes for microbial populations.

Main Results:

• Recipient microbial populations can expand the ecological niches of their feeders or competitors.
• A distinct zone of OM and nitrate co-limitation was identified, leading to [Formula: see text] production without consumption.
• Anammox bacteria were found to occupy a broader range of OM and nitrate supply regimes compared to denitrifiers.

Conclusions:

• Microbial interaction networks are directly linked to global-scale biogeochemical fluxes.
• Ecological theory can be extended to understand multi-resource systems with complex competitive and dependent interactions.
• Understanding these microbial dynamics is key to predicting nitrogen cycle alterations and greenhouse gas emissions.