Connecting Molecular Biomarkers, Mineralogical Composition, And Microbial Diversity From Mars Analog Lava Tubes
Lanzarote (Canary Islands, Spain) is one of the best terrestrial analogs to Martian volcanology. Particularly, Lanzarote lava tubes may offer access to recognizably preserved chemical and morphological biosignatures valuable for astrobiology.
By combining microbiological, mineralogical, and organic geochemistry tools, an in-depth characterization of speleothems and associated microbial communities in lava tubes of Lanzarote is provided.
The aim is to untangle the underlying factors influencing microbial colonization in Earth’s subsurface to gain insight into the possibility of similar subsurface microbial habitats on Mars and to identify biosignatures preserved in lava tubes unequivocally.
Graphical abstract — Science of The Total Environment
The microbial communities with relevant representativeness comprise chemoorganotrophic, halophiles, and/or halotolerant bacteria that have evolved as a result of the surrounding oceanic environmental conditions. Many of these bacteria have a fundamental role in reshaping cave deposits due to their carbonatogenic ability, leaving behind an organic record that can provide evidence of past or present life.
Based on functional profiling, we infer that Crossiella is involved in fluorapatite precipitation via urea hydrolysis and propose its Ca-rich precipitates as compelling biosignatures valuable for astrobiology.
Conceptual diagram showing different environments under which secondary minerals precipitate in lava tube (cal: calcite, fa: fluorapatite, gyp: gypsum, ha: halite, op: opal) and their associated microbial assemblages. — Science of The Total Environment
In this sense, analytical pyrolysis, stable isotope analysis, and chemometrics were conducted to characterize the complex organic fraction preserved in the speleothems and find relationships among organic families, microbial taxa, and precipitated minerals.
We relate organic compounds with subsurface microbial taxa, showing that organic families drive the microbiota of Lanzarote lava tubes. Our data indicate that bacterial communities are important contributors to biomarker records in volcanic-hosted speleothems. Within them, the lipid fraction primarily consists of low molecular weight n-alkanes, α-alkenes, and branched-alkenes, providing further evidence that microorganisms serve as the origin of organic matter in these formations.
The ongoing research in Lanzarote’s lava tubes will help develop protocols, routines, and predictive models that could provide guidance on choosing locations and methodologies for searching potential biosignatures on Mars.
Representative FESEM images of: samples CN1 (A–C) and CN2 (D–F) from Cueva de los Naturalistas; samples PE01 (G–I) and PE03 (J–L), Paso Esqueleto Cave; sample LB04 (M,N), Cueva Las Breñas, and sample MR02 (O) from Montaña Rajada Cave. — Science of The Total Environment
Connecting molecular biomarkers, mineralogical composition, and microbial diversity from Mars analog lava tubes, Science of The Total Environment (open access)
Science of the Total Environment ( IF 9.8 ) Pub Date: 2023-12-26 , DOI:10.1016/j.scitotenv.2023.169583
Vera Palma, José L. González-Pimentel, Nicasio T. Jimenez-Morillo, Francesco Sauro, Sara Gutiérrez-Patricio, José M. De la Rosa, Ilaria Tomasi, Matteo Massironi, Bogdan P. Onac, Igor Tiago, José A. González-Pérez, Leonila Laiz, Ana T. Caldeira, Beatriz Cubero, Ana Z. Miller
Astrobiology
