Microbiology of a NaCl stalactite ‘salticle’ in Triassic halite

Summary Large regions of Earth's surface are underlain by salt deposits that evaporated from ancient oceans and are populated by extreme halophilic microbes. Some of these halophiles may have been preserved over geological timescales within hypersaline fluid inclusions, but ingresses of water a...

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Bibliographic Details
Published in:Environmental microbiology 2021-07, Vol.23 (7), p.3881-3895
Main Authors: Thompson, Thomas P., Kelly, Stephen A., Skvortsov, Timofey, Plunkett, Gill, Ruffell, Alastair, Hallsworth, John E., Hopps, Jason, Gilmore, Brendan F.
Format: Article
Language:English
Subjects:
Abundance
Anaerobic respiration
Anthropogenic factors
Astrobiology
Brines
Earth surface
Ecophysiology
Evaporites
Fluid inclusions
Genes
Halite
Halites
Ionizing radiation
Microbiology
Microbiomes
Microorganisms
Oceans
Osmoregulation
Oxidation resistance
Oxidative stress
Protein biosynthesis
Protein synthesis
Salt deposits
Sodium chloride
Soil
Soil microorganisms
Soils
Triassic
Water activity
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Summary:Summary Large regions of Earth's surface are underlain by salt deposits that evaporated from ancient oceans and are populated by extreme halophilic microbes. Some of these halophiles may have been preserved over geological timescales within hypersaline fluid inclusions, but ingresses of water and/or anthropogenic activities can lead to the formation of alternative habitats, including NaCl stalactites or other speleothems. While the microbiology of ancient evaporites has been well studied, the ecology of these recently formed structures is less‐well understood. Here, the microbiology of a NaCl stalactite (‘salticle’) in a Triassic halite mine is characterized. The specific aims were to determine the presence of fluid inclusions, determine the microbial structure of the salticle compared with a nearby brine‐pool and surficial soil, and characterize the ecophysiological capabilities of this unique ecosystem. The salticle contained fluid inclusions, and their microbiome was composed of Euryarchaetota, Proteobacteria, and Actinobacteria, with Haloarchaea in greater abundance than brine‐pool or soil microbiomes. The salticle metagenome exhibited a greater abundance of genes involved in osmoregulation, anaerobic respiration, UV resistance, oxidative stress, and stress‐protein synthesis relative to the soil microbiome. We discuss the potential astrobiological implications of salticles as enclosed salt‐saturated habitats that are protected from ionizing radiation and have a stable water activity.
ISSN:1462-2912
1462-2920
DOI:10.1111/1462-2920.15524