Genomic composition and dynamics among Methanomicrobiales predict adaptation to contrasting environments

Area of Science:

• Microbiology
• Genomics
• Biogeochemistry

Background:

• Methanomicrobiales are abundant hydrogenotrophic methanoarchaea in anoxic environments.
• They play crucial roles in greenhouse gas emissions and waste conversion to methane.
• Their genomic and physiological bases for widespread distribution are largely unknown.

Purpose of the Study:

• To investigate the genomic diversity and evolutionary adaptations of Methanomicrobiales.
• To identify genes and pathways contributing to their success in various habitats.
• To compare their metabolic strategies with other hydrogenotrophic methanogens.

Main Methods:

• Comparative genomics of nine diverse Methanomicrobiales strains.
• Pangenome analysis and reconstruction of gene flow.
• Identification of genes related to nutrient transport, energy conservation, and metabolism.

Main Results:

• Most strains showed genome expansion, while Methanocorpusculum labreanum exhibited genome downsizing.
• Peat-dwelling Methanomicrobiales possess adaptations for nutrient acquisition and likely use H+ gradients.
• Methanomicrobiales lack the canonical MvhABGD electron bifurcation system found in other methanogens.

Conclusions:

• Methanomicrobiales exhibit unique genomic features and metabolic strategies, including distinct electron trafficking mechanisms.
• These differences may influence their interactions with syntrophic partners and their ecological roles.
• Further functional studies are needed to elucidate their unique electron transfer processes.