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Abstract EANA2025-145


Lava Tubes as Planetary Analogs: Early Stages of Microbial Colonization Following the Tajogaite Eruption

Sara Gutiérrez-Patricio (1), Pedro Nolasco-Jiménez (1), Octavio Fernandez (2), Alba Gómez-Arias (1), Ana Pires (3), Juana Vegas (4), Ana Z. Miller (1),*
(1) Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Sevilla, España (2) GETebexcorade – La Palma, Federación Canaria de Espeleología, La Palma, Spain. (3) Institute for Systems and Computer Engineering, Technology and Science (INESCTEC), Centre for Robotics and Autonomous Systems (CRAS), Polytechnic of Porto, Porto, Portugal. (4) Instituto Geológico y Minero de España (IGME-CSIC), Ríos Rosas 23, 28003 Madrid, Spain. *Corresponding author: anamiller@irnas.csic.es


Volcanic eruptions are among the most transformative forces on Earth, rapidly reshaping landscapes and creating new ecosystems from molten rock. The 2021 Tajogaite eruption (La Palma, Canary Islands) formed an extensive network of lava tubes, offering a unique opportunity to investigate the pioneering inhabitants of one of the youngest subterranean ecosystems on the planet.  

These newly formed volcanic environments, defined by limited energy sources, high thermal conditions, and stable microclimates, offer a unique and fleeting opportunity to observe the initial stages of microbial colonization and ecological development from their very beginning. In addition, lava tubes serve as analogs for the search for life on other planets, providing natural setting for critical questions in astrobiology and planetary science.

In this study, we characterized early microbial colonization using both culture-based methods and high-throughput 16S rRNA gene sequencing. Our findings reveal that microbial communities are dominated by extremophiles, including bacteria from the phyla Actinomycetota, Bacillota, and Pseudomonadota, as well as chemolithotrophic archaea from the phylum Euryarchaeota. In parallel, we identified bacterial taxa typically associated with animal hosts and organic waste, such as Staphylococcus, Sphingomonas, and Filibacter tadaridae, suggesting a significant input of exogenous organic matter, likely derived from guano, feathers, and rodent activity near cave entrances.

Furthermore, the detection of microbial taxa involved in nitrogen fixation, sulfur oxidation, and carbon cycling indicates the early establishment of metabolic networks capable of supporting ecosystem development over time within the lava tubes.

Our results demonstrate that early microbial colonization in the newly formed lava tubes of La Palma is driven by two main forces: (1) the selective pressures imposed by extreme environmental conditions, and (2) stochastic seeding by biological vectors.

These findings contribute not only to our understanding of microbial succession in newly formed subterranean volcanic environments but also highlight the significance of lava tubes as planetary analogs. They offer valuable insights for the search for microbial life in Martian lava tubes and the processes that may govern ecosystem development under extreme.

Keywords: microbial diversity, volcanic caves, microbial succession, geomicrobiology, astrobiology, La Palma

Acknowledgements: This work was funded by the Spanish Agency of Research (MCIN/AEI/10.13039/501100011033) and the European Union (Next Generation EU/PRTR funding) grants TED2021-130683B-C21 and TED2021-130683B-C22, and by the Regional Government of Andalusia through the MICROLAVA project (PROYEXCEL_00185). The support from the Spanish National Research Council (CSIC) through the intramural project PIE_20214AT021 is also acknowledged.