Microbes from Brine Systems with Fluctuating Salinity Can Thrive under Simulated Martian Chemical Conditions.

Matthew Kelbrick,Nisha K Ramkissoon,James A W Oliver,Michael C Macey,Ben P Stephens,André Antunes,Susanne P Schwenzer,Ezgi Kucukkilic-Stephens,Amy Dugdale

doi:10.3390/life12010012

Abstract

The waters that were present on early Mars may have been habitable. Characterising environments analogous to these waters and investigating the viability of their microbes under simulated martian chemical conditions is key to developing hypotheses on this habitability and potential biosignature formation. In this study, we examined the viability of microbes from the Anderton Brine Springs (United Kingdom) under simulated martian chemistries designed to simulate the chemical conditions of water that may have existed during the Hesperian. Associated changes in the fluid chemistries were also tested using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The tested Hesperian fluid chemistries were shown to be habitable, supporting the growth of all of the Anderton Brine Spring isolates. However, inter and intra-generic variation was observed both in the ability of the isolates to tolerate more concentrated fluids and in their impact on the fluid chemistry. Therefore, whilst this study shows microbes from fluctuating brines can survive and grow in simulated martian water chemistry, further investigations are required to further define the potential habitability under past martian conditions.

Highlights

Introduction published maps and institutional affilWater is essential to all known life
A range of techniques was applied to assess the viability of microbes from a martian analogue environment under simulated martian chemical conditions relevant to the waters modelled to have existed on the surface of Mars during the Noachian–Hesperian transition
Mars simulation experiments, which identified that microbial growth was viable in water chemistries analogous to those proposed to have existed on early Mars [23,41,47]

Summary

Introduction

Introduction published maps and institutional affilWater is essential to all known life. Not the only prerequisite for habitability, it is the primary sign of potential past and present habitable environments outside of. The majority of habitable martian environments are suggested to have existed early in Mars’s history, during the Noachian era (4.0–3.7 Gya) as surface water existed at that time [1,2,3,4]. Some water sources are suggested to have persisted to the modern day (Amazonian era; 2.9 Gya to present), residing on the surface as evaporated streams or icecaps, and in the subsurface as groundwater in regions of high geothermal heat flux [3,5,6,7]. The transition between the Noachian and the Hesperian eras (3.7–2.9 Gya) is characterised by decreased volcanism and atmospheric erosion, leading to a colder and dryer iations The historical presence of water on Mars is evidenced by geomorphological features, such as streambeds (e.g., [6]), and water-rock interactions documented by minerals that have undergone hydrous-alteration (e.g., [8,9,10])

Methods

Findings

Discussion

Conclusion