Membrane lipid patterns typify distinct anaerobic methanotrophic consortia

Area of Science:

• Geochemistry
• Microbiology
• Marine Science

Background:

• Anaerobic oxidation of methane (AOM) is a significant sink for methane, a potent greenhouse gas, in marine settings.
• Diverse microbial communities, primarily archaea (ANME-1, ANME-2) and sulfate-reducing bacteria, drive AOM.
• Specific lipid biomarkers have been identified for AOM-mediating consortia in various environments.

Purpose of the Study:

• To investigate the differences in lipid profiles of microbial consortia involved in AOM.
• To correlate specific lipid biomarkers with distinct archaeal clusters (ANME-1 and ANME-2) in AOM-driven carbonate reefs.
• To assess the potential of these lipid biomarkers for studying past and present methane environments.

Main Methods:

• Sampling of microbial consortia from AOM-driven carbonate reefs in the Black Sea.
• Analysis of lipid composition, focusing on archaeal and bacterial lipids.
• Phylogenetic identification of dominant archaeal clusters (ANME-1, ANME-2) and bacterial groups.

Main Results:

• Significant differences in lipid composition were observed between ANME-1 and ANME-2 dominated communities.
• ANME-1 communities yielded internally cyclized tetraether lipids, while ANME-2 communities produced sn-2-hydroxyarchaeol, crocetane, and crocetenes.
• Distinct bacterial lipids were associated with each archaeal group: nonisoprenoidal glycerol diethers with ANME-1 and ester-linked diglycerides with ANME-2.
• ANME-1 archaea and associated bacteria appear adapted to low methane concentrations and wide temperature ranges.

Conclusions:

• Lipid profiles serve as reliable indicators for distinguishing between ANME-1 and ANME-2 dominated AOM communities.
• These findings provide valuable molecular tools for reconstructing paleoenvironmental conditions and understanding methane cycling.
• The study highlights the ecological and biogeochemical significance of microbial consortia in marine methane sinks.