Lower hydrogen flux leads to larger carbon isotopic fractionation of methane and biomarkers during hydrogenotrophic methanogenesis

摘要

The isotopic composition of lipid biomarkers and biomass in sedimentary environments are widely used to infer microbial metabolisms and constrain carbon cycling processes. It has been observed that metabolic energy availability in the form of H-2 impacts the stable carbon isotopes of CH4 during hydrogenotrophic methanogenesis, but it is unknown whether this relationship extends to lipids and amino acids. Since lipids and amino acids are long-lived, they can be used to reconstruct past conditions over geologic timescales. Therefore, the controls on their isotopic signatures are important to constrain to better interpret past environments.