TY - JOUR

T1 - A novel biomarker for deep-time methanogenesis

T2 - perspectives from nickel isotope fractionation in modern microbialites

AU - Hohl, Simon V.

AU - Bian, Xiaopeng

AU - Viehmann, Sebastian

AU - Yang, Shun-Chung

AU - Raad, Robert J.

AU - Meister, Patrick

AU - John, Seth G.

N1 - Publisher Copyright: © 2025 Elsevier B.V.

PY - 2025

Y1 - 2025

N2 - Activity of methanogenic archaea on early Earth is mainly deduced based on modern processes and supported by the carbon isotope record (δ 13C carb). Recently, Ni isotopes preserved in authigenic carbonate have been proposed to provide a further signature to trace methanogenesis in ancient environments because methanogens require nickel (Ni) as a metal co-factor for key enzymes to produce CH 4. Further, uptake in cultured methanogens has been shown to fractionate stable Ni isotopes (δ 60Ni) from their aqueous medium, a process that could potentially be recorded in authigenic carbonates. Therefore, Ni isotopes in microbialites could provide valuable insights into whether methanogenesis was active in ancient microbial habitats. Here, we explore this idea using combined C–Ni isotope analyses on individual layers of microbial carbonates from the Lagoa Salgada, a Holocene ephemeral lake in Brazil where abundant microbialites formed in the presence of methanogens. Microbial carbonates show distinct positive δ 13C carb (up to +20 ‰) at negative δ 60Ni carb values (down to -1.36 ‰) that can be linked to methanogenic metabolism—in contrast to higher δ 60Ni of ambient gastropod shells (+1.72 ‰) and authigenic non-lithified sediments from the lagoon (+1.1 to +1.58 ‰). Our results show that Ni isotopes in microbial carbonates are a promising novel isotope proxy for methanogenic Ni isotope fractionation. We anticipate this study as a starting point for future research on combined metallome and microbiome evolution reflected in microbialites through time on Earth and beyond.

AB - Activity of methanogenic archaea on early Earth is mainly deduced based on modern processes and supported by the carbon isotope record (δ 13C carb). Recently, Ni isotopes preserved in authigenic carbonate have been proposed to provide a further signature to trace methanogenesis in ancient environments because methanogens require nickel (Ni) as a metal co-factor for key enzymes to produce CH 4. Further, uptake in cultured methanogens has been shown to fractionate stable Ni isotopes (δ 60Ni) from their aqueous medium, a process that could potentially be recorded in authigenic carbonates. Therefore, Ni isotopes in microbialites could provide valuable insights into whether methanogenesis was active in ancient microbial habitats. Here, we explore this idea using combined C–Ni isotope analyses on individual layers of microbial carbonates from the Lagoa Salgada, a Holocene ephemeral lake in Brazil where abundant microbialites formed in the presence of methanogens. Microbial carbonates show distinct positive δ 13C carb (up to +20 ‰) at negative δ 60Ni carb values (down to -1.36 ‰) that can be linked to methanogenic metabolism—in contrast to higher δ 60Ni of ambient gastropod shells (+1.72 ‰) and authigenic non-lithified sediments from the lagoon (+1.1 to +1.58 ‰). Our results show that Ni isotopes in microbial carbonates are a promising novel isotope proxy for methanogenic Ni isotope fractionation. We anticipate this study as a starting point for future research on combined metallome and microbiome evolution reflected in microbialites through time on Earth and beyond.

KW - Biogeochemical metal cycling

KW - Carbonate geochemistry

KW - Lagoa Salgada

KW - Methanogens

KW - Microbialites

KW - Ni isotopes

UR - http://www.scopus.com/inward/record.url?scp=105007788038&partnerID=8YFLogxK

U2 - 10.1016/j.epsl.2025.119492

DO - 10.1016/j.epsl.2025.119492

M3 - Article

VL - 666

JO - Earth and Planetary Science Letters

JF - Earth and Planetary Science Letters

SN - 0012-821X

M1 - 119492

ER -