Redox distribution of Asgard archaea and co-occurring taxa in microbial mats from an early Proterozoic ecosystem analog
Abstract
Increasing evidence supports that eukaryotes originated from the symbiosis of an Asgard archaeon, the alphaproteobacterial ancestor of mitochondria, and possibly additional bacterial contributions. Eukaryogenesis likely occurred in redox-transition environments such as microbial mats or shallow sediments ~2 billion years ago, when atmospheric oxygen was far lower than today. We investigated Asgard-enriched microbial mats from the low-oxygen, sulfidic Catherine volcano lake (Afar region, Ethiopia), mimicking early Proterozoic conditions. 16S rRNA gene metabarcoding, metagenomics, and metagenome-assembled genome analyses across redox-stratified layers of in situ and mesocosm-maintained mats revealed that Asgardarchaeota thrived in the sulfate-reduction zone, mainly co-occurring with Desulfurobacterota-Myxococcota, among others. Lokiarchaeia and Thorarchaeia preferred anoxic layers. Within Heimdallarchaeia, Heimdallarchaeales were enriched in upper layers, correlating with oxygen-tolerant hydrogenase and sulfate-reduction genes, and Hodarchaeales, in anoxic layers, correlating with methanogenesis. Although reactive-oxygen-species defense mechanisms were widespread, Asgardarchaeota lacked aerobic respiration. These results support the hypothesis that Asgard archaea engaged primarily in syntrophic interactions with sulfate-reducers under early-Earth-like conditions.
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BibTeX
@article{gutierrezpreciado2026redox,
title = {{Redox distribution of Asgard archaea and co-occurring taxa in microbial mats from an early Proterozoic ecosystem analog}},
author = {Ana Gutiérrez-Preciado and Agathe Struillou and Lewen Liang and Miguel Iniesto and Philippe Deschamps and Laura Eme and Yvan Zivanovic and José López-García and Karim Benzerara and David Moreira and Purificación López-García},
journal = {npj Biofilms and Microbiomes},
year = {2026},
month = oct,
doi = {10.1038/s41522-026-01148-8},
url = {https://hal.science/hal-05837597v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Redox distribution of Asgard archaea and co-occurring taxa in microbial mats from an early Proterozoic ecosystem analog
AU - Ana Gutiérrez-Preciado
AU - Agathe Struillou
AU - Lewen Liang
AU - Miguel Iniesto
AU - Philippe Deschamps
AU - Laura Eme
AU - Yvan Zivanovic
AU - José López-García
AU - Karim Benzerara
AU - David Moreira
AU - Purificación López-García
PY - 2026
DA - 2026/10/02
JO - npj Biofilms and Microbiomes
DO - 10.1038/s41522-026-01148-8
UR - https://hal.science/hal-05837597v1
AB - Increasing evidence supports that eukaryotes originated from the symbiosis of an Asgard archaeon, the alphaproteobacterial ancestor of mitochondria, and possibly additional bacterial contributions. Eukaryogenesis likely occurred in redox-transition environments such as microbial mats or shallow sediments ~2 billion years ago, when atmospheric oxygen was far lower than today. We investigated Asgard-enriched microbial mats from the low-oxygen, sulfidic Catherine volcano lake (Afar region, Ethiopia), mimicking early Proterozoic conditions. 16S rRNA gene metabarcoding, metagenomics, and metagenome-assembled genome analyses across redox-stratified layers of in situ and mesocosm-maintained mats revealed that Asgardarchaeota thrived in the sulfate-reduction zone, mainly co-occurring with Desulfurobacterota-Myxococcota, among others. Lokiarchaeia and Thorarchaeia preferred anoxic layers. Within Heimdallarchaeia, Heimdallarchaeales were enriched in upper layers, correlating with oxygen-tolerant hydrogenase and sulfate-reduction genes, and Hodarchaeales, in anoxic layers, correlating with methanogenesis. Although reactive-oxygen-species defense mechanisms were widespread, Asgardarchaeota lacked aerobic respiration. These results support the hypothesis that Asgard archaea engaged primarily in syntrophic interactions with sulfate-reducers under early-Earth-like conditions.
SN - 2055-5008
ER -