# Carbon monoxide dehydrogenase-encoding microorganisms in volcanic astrobiological analogues: an enzyme system to investigate the evolution of life

## TL;DR

This paper explores how microbes in volcanic environments use carbon monoxide to generate energy, shedding light on life's evolution in extreme conditions and potential habitability on other planets.

## Contribution

The study identifies CODH gene distribution in volcanic sites and highlights microbial adaptability in extreme environments.

## Key findings

- Genomic evidence confirms CODH genes in eight volcanic sites, showing their role in CO oxidation.
- Aerobic coxL genes are abundant and conserved, while anaerobic genes vary by site and community.
- Desulfobacterota at Poás Volcano show genetic versatility across nine gene clusters.

## Abstract

Volcanic environments provide analogues for studying the origin of life and its persistence under extreme conditions on early Earth and other planetary bodies. Pioneering microbes that oxidise inorganic gases, such as carbon monoxide (CO), provide energy for survival and initiate primary succession. Similar geological and atmospheric conditions shaped by volcanism, meteoritic impacts, and tidal heating have existed, or still exist, on Mars, Venus, and icy moons, where CO may serve as a metabolic substrate. This review explores the evolutionary significance of CO dehydrogenase (CODH), an enzyme responsible for the oxidation of CO to carbon dioxide, thereby linking geochemical energy fluxes to the emergence of biological carbon. Genomic evidence from eight globally distributed volcanic sites confirms the presence of genes encoding CODH. Genes encoding aerobic CO oxidation (coxL) were consistently abundant and conserved, whereas genes encoding anaerobic oxidation (cdh- and coo-related genes) showed site-specific dominance and variability, reflecting differences in microbial community composition and environmental conditions. At Poás Volcano, several taxa, particularly members of Desulfobacterota, exhibited genetic versatility across nine gene clusters, highlighting their adaptive capacity. These findings demonstrate how trace gas metabolism can support microbial survival in volcanic soils, providing insight into potential habitability on other planetary bodies.

Volcanic ecosystems reveal how ancient CO-oxidizing microbes evolved CODH genes, enabling energy generation and adaptive versatility across diverse extreme environments on Earth and other planetary bodies influenced by geochemical processes.