Water Activities of Acid Brine Lakes Approach the Limit for Life

Kathleen C Benison; William K O'Neill; David Blain; John E Hallsworth

doi:10.1089/ast.2020.2334

Water Activities of Acid Brine Lakes Approach the Limit for Life

Kathleen C Benison, William K O'Neill, David Blain, John E Hallsworth

School of Biological Sciences

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25 Citations (Scopus)

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Abstract

Water activity is an important characteristic for describing unusual waters and is a determinant of habitability for microorganisms. However, few empirical studies of water activity have been done for natural waters exhibiting an extreme chemistry. Here, we investigate water activity for acid brines from Western Australia and Chile with pH as low as 1.4, salinities as high as 32% total dissolved solids, and complex chemical compositions. These acid brines host diverse communities of extremophilic microorganisms, including archaea, bacteria, algae, and fungi, according to metagenomic analyses. For the most extreme brine, its water activity (0.714) was considerably lower than that of saturated (pure) NaCl brine. This study provides a thermodynamic insight into life within end-member natural waters that lie at, or possibly beyond, the very edge of habitable space on Earth.

Original language	English
Number of pages	12
Journal	Astrobiology
Volume	21
Issue number	7
Early online date	05 Apr 2021
DOIs	https://doi.org/10.1089/ast.2020.2334
Publication status	Early online date - 05 Apr 2021

Keywords

Acid brines
Extremophiles
Habitability. Astrobiology 21, xxx–xxx
Halophile ecology
Water activity

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10.1089/ast.2020.2334Licence: CC BY-NC-ND

Water Activities of Acid Brine Lakes Approach the Limit for Life
© 2021 The Authors. This is an open access article published under a Creative Commons Attribution-NoDerivs License (https://creativecommons.org/licenses/by-nd/4.0/), which permits reproduction and redistribute in any medium, provided the author and source are cited and any subsequent modifications are not distributed.
Final published version, 325 KBLicence: CC BY-NC-ND

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title = "Water Activities of Acid Brine Lakes Approach the Limit for Life",

abstract = "Water activity is an important characteristic for describing unusual waters and is a determinant of habitability for microorganisms. However, few empirical studies of water activity have been done for natural waters exhibiting an extreme chemistry. Here, we investigate water activity for acid brines from Western Australia and Chile with pH as low as 1.4, salinities as high as 32% total dissolved solids, and complex chemical compositions. These acid brines host diverse communities of extremophilic microorganisms, including archaea, bacteria, algae, and fungi, according to metagenomic analyses. For the most extreme brine, its water activity (0.714) was considerably lower than that of saturated (pure) NaCl brine. This study provides a thermodynamic insight into life within end-member natural waters that lie at, or possibly beyond, the very edge of habitable space on Earth.",

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AB - Water activity is an important characteristic for describing unusual waters and is a determinant of habitability for microorganisms. However, few empirical studies of water activity have been done for natural waters exhibiting an extreme chemistry. Here, we investigate water activity for acid brines from Western Australia and Chile with pH as low as 1.4, salinities as high as 32% total dissolved solids, and complex chemical compositions. These acid brines host diverse communities of extremophilic microorganisms, including archaea, bacteria, algae, and fungi, according to metagenomic analyses. For the most extreme brine, its water activity (0.714) was considerably lower than that of saturated (pure) NaCl brine. This study provides a thermodynamic insight into life within end-member natural waters that lie at, or possibly beyond, the very edge of habitable space on Earth.

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Water Activities of Acid Brine Lakes Approach the Limit for Life

Abstract

Keywords

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