Microbial metabolism and adaptations in Atribacteria-dominated methane hydrate sediments

Area of Science:

• Microbiology
• Geochemistry
• Biogeoscience

Background:

• Gas hydrates contain vast natural gas reserves, but their associated microbial ecosystems are largely unexplored.
• Understanding these microbiomes is crucial for comprehending deep subsurface carbon cycling and microbial adaptation.

Purpose of the Study:

• To investigate the metabolic and biosynthetic potential of microbial communities within methane hydrate-bearing sediments.
• To identify novel microbial adaptations and functions in the deep subsurface environment.

Main Methods:

• Bioprospecting using 16S rRNA gene amplicon sequencing, metagenomics, and metaproteomics.
• Analysis of microbial communities across different geochemical zones (sulfate-methane transition, metal reduction, gas hydrate stability).
• Genomic binning to reconstruct microbial genomes and identify functional genes.

Main Results:

• Atribacteria sequences increased with sediment depth, predominantly belonging to the JS-1-Genus 1.
• Identified bacterial fermentation supplying acetate for methanogenesis and driving iron reduction.
• Discovered a Ni-Fe hydrogenase-Na+ /H+ antiporter supercomplex (Hun) in Atribacteria and other deep subsurface bacteria.
• Atribacteria exhibited adaptations to extreme conditions, including synthesis of di-myo-inositol-phosphate and expression of specific transporters and proteins.

Conclusions:

• The study reveals significant metabolic and biosynthetic potential within gas hydrate-associated microbiomes.
• Atribacteria play a key role in carbon cycling and possess unique adaptations for survival in extreme deep subsurface environments.
• Findings contribute to understanding microbial life in underexplored, energy-rich environments.