Microbial Niche Differentiation during Nitrite-Dependent Anaerobic Methane Oxidation

Area of Science:

• Environmental Microbiology
• Biogeochemistry
• Microbial Ecology

Background:

• Nitrite-dependent anaerobic methane oxidation (n-DAMO) is crucial for global methane and nitrogen cycling.
• Understanding the physiological basis of n-DAMO bacterial niche differentiation is limited despite their widespread detection.

Purpose of the Study:

• To elucidate the microbial niche differentiation of n-DAMO bacteria.
• To investigate the physiological and kinetic factors driving niche partitioning in n-DAMO bacteria.

Main Methods:

• Long-term reactor operations with controlled nitrite concentrations.
• Genome-centered omics (metatranscriptomics) analysis.
• Kinetic analysis (half-saturation constants, inhibition thresholds).

Main Results:

• Reactor operation shifted populations: 'Ca. M. oxyfera' dominated low nitrite, 'Ca. M. sinica' dominated high nitrite.
• 'Ca. M. oxyfera' showed enhanced nitrite uptake functions; 'Ca. M. sinica' exhibited stronger stress response and nitrite reduction capabilities.
• Kinetic parameters (nitrite affinity and inhibition thresholds) directly correlated with genomic and transcriptomic findings, explaining niche differentiation.

Conclusions:

• Biochemical characteristics, particularly nitrite affinity and inhibition kinetics, are key determinants of n-DAMO bacterial niche differentiation.
• This study provides a mechanistic understanding of how different n-DAMO bacteria coexist and partition resources in varying environments.