Survival of halophiles of Altai lakes under extreme environmental conditions: implications for the search for Martian life

Abstract

Mars is considered to be one of the most favourable places in the Solar System to search for past and present life. In the past Mars was warmer and wetter, so terrestrial halophiles can be regarded as analogues of hypothetical ancient Martian halophiles. In this study we used microorganisms from unique Altai region (Russia) to estimate the capability of terrestrial bacteria and archaea to survive at low temperatures and high concentration of salts and metals, similar to the Martian environment. The current report demonstrates that both halophilic archaea and halotolerant bacteria from saline lakes of the Altai region may be considered as analogues of ancient Martian organisms, since they are able to withstand conditions that hypothetically existed in subsurface layers of the early Mars (low temperatures, salt solutions with a high content of NaCl) with only slight decrease in viability. We also found that the studied microorganisms can use some organic substances found in meteorites. We consider that transfer of unicellular halophiles from Earth to Mars was possible, and, moreover, they could successfully survive and grow on early Mars. Adjusting our growth media to the chemical composition of the lakes, from which the studied strains were isolated, resulted in significant increase in survival and growth rates. Certain strains could survive several freeze–thaw cycles at −70 °C typical for Martian nights.

Farming on Mars: Treatment of basaltic regolith soil and briny water simulants sustains plant growth

“…Bacterial species grow in extremely high concentrations of solutes including saturated NaCl and MgSO 4 [ 55 , 56 ]. Halobacteria from saline lakes (considered as analogues of ancient martian organisms) withstand low temperatures and high NaCl content similar to conditions in Mars [ 57 ]. Terrestrial microbes including fungus grow in densest brines such as those on Mars [ 16 , 17 ].…”

Halophilic Plant-Associated Bacteria with Plant-Growth-Promoting Potential

“…This makes the genus an interesting subject of research for its potential use in bioremediation of saline soils, as well as in the production of salt-tolerant crops. Strains of Kushneria have been isolated from a variety of different salty environments, including a solar saltern, the leaves of black mangroves, sea water, salt mines, cured meats, and salt fermented foods [117][118][119][120][121][122][123]. Many species in this genus are adapted to hypersaline environments, and different strains have been isolated from the rhizosphere as well as the endosphere of halophytes [119,124].…”

Unearthing terrestrial extreme microbiomes for searching terrestrial-like life in the Solar System

“…One of the major astrobiological interests for Mars habitability is the natural accumulation of perchlorate, which is soils surface at concentrations between 0.5 and 1%. Especially extreme halophiles, being able to tolerate high levels of this compound, are considered among the best potential models for survival on Mars [31][32]. The most studied belong to the archaeal phyla Euryarchaeota and Crenarchaeota that are known to growth at high perchlorate concentration (0.5-1 M) and to a group of chlorine-resistant (e.g.…”