SWR Winter Tech 2025: [Microbial Symphony of Nitrogen Cycling within Lava Cave Environments]

Описание: A presentation from the 2025 National Speleological Society Southwest Region Winter Technical Meeting, held December 6th, 2025 at the University of New Mexico.
https://swr.caves.org/
https://caves.org/

Published with permission from the authors and presenters.

A Microbial Symphony of Nitrogen Cycling: Syntrophic Relationships between Archaeal and Bacterial Ppecies within Lava Cave Environments
Biology, University of New Mexico
Rylan E. Stumbaugh
Joseph J. Medley
Jennifer J. M. Hathaway
Cristina Takacs-Vesbach
Diana E. Northup

Abstract:

Lava cave systems are a valuable reservoir of microbial life, housing hundreds of species of Archaea and Bacteria. These microbial deposits shape the environment by conducting redox reactions that contribute to secondary mineral formation, contain novel antibiotic genes, and are considered analog systems for astrobiology research. Further, within these environments, microorganisms are the foundational organisms responsible for cycling growth-limiting elements, such as nitrogen, to sustain the microbial ecosystem. However, questions remain: what genera of Archaea and Bacteria associated with nitrogen cycling roles are present, and do they engage in syntrophic relationships to accomplish their nitrogen cycling goals? To address this, our study investigates prokaryotic community composition by analysis of the 16S rRNA gene using Illumina MiSeq sequencing. Thirty-seven samples of microbial deposits from coralloids, microbial mats, mineral crusts, and moonmilk were collected across three caves of the Kipuka Kanohina Cave System on the Big Island of Hawai’i.

Initial results show multiple nitrogen cycling-associated genera, with a high abundance of Nitrososphaera and Nitrosopumilus in particular, which are associated with ammonia oxidation processes. Further analysis will allow us to examine bacterial and archaeal species co-occurrence to identify potential syntrophic relationships. Future work includes identifying the sources of nitrogen for these microbial communities using bulk stable isotope analysis of 15N. These results will provide foundational insight into how these communities acquire and retain nitrogen to establish and perpetuate their communities’ growth in lava caves, a small piece of a complex puzzle necessary to expand our knowledge of how to approach the study and understanding of these microbial ecosystems.