297-4 Metagenomic and Experimental Insights into Microbial Olivine Dissolution and Modification of Volcanic Cave Walls

Session: Caves and Karst Through Space and Time: Biogeochemistry, Climate, and Astrobiology (Posters)

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Previous research has shown that iron-oxidizing microorganisms from volcanic caves can survive on olivine as the sole energy source. However, the mechanisms and organisms involved and their extent within natural systems have not been fully investigated. In this study, we combined culture-dependent and culture-independent methods to assess whether microbes from volcanic caves can utilize olivine and other iron-bearing minerals for survival, and whether evidence of this process may be detected in volcanic cave environments. Initial long-term enrichments on crushed olivine revealed diverse microbial communities, including abundant Acinetobacter, Pseudomonas, Massilia, Aliihoeflea, and Turicella, although growth and development of these microbial communities did not appear to impact rates of olivine dissolution compared to abiotic controls. We are comparing these to new results from ongoing experiments with polished and crushed olivine and basalt chips. We also characterized microbial communities from the walls of lava tubes from El Malpais National Monument using metagenomic and high throughput 16S rRNA gene sequencing. rRNA gene libraries show that microbial communities from wall and floor deposits differ by cave zone and are diverse overall with abundant members of the Actinobacteriota such as Rubrobacter and Actinomycetospora, and of archaea in the families Nitrososphaeraceae and Halococcaceae. To explore the genomic potential of populations associated with secondary mineral deposits on the cave walls, we generated metagenomes and recovered high quality bins from several wall crusts, including several with the potential for chemolithoautotrophic growth. We will share insights from both the experimental and culture independent analyses into the factors shaping cave microbial communities, as well as their capacities for modifying basaltic cave walls through primary mineral dissolution and/or secondary mineral precipitation.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9405

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