Provision of water by halite deliquescence forNostoc communebiofilms under Mars relevant surface conditions

Abstract

Motivated by findings of new mineral related water sources for organisms under extremely dry conditions on Earth we studied in an interdisciplinary approach the water sorption behaviour of halite, soil component and terrestrial Nostoc commune biofilm under Mars relevant environmental conditions. Physicochemical methods served for the determination of water sorption equilibrium data and survival of heterotrophic bacteria in biofilm samples with different water contents was assured by recultivation. Deliquescence of halite provides liquid water at temperatures <273 K and may serve as water source on Mars during the morning stabilized by the CO 2 atmosphere for a few hours. The protecting biofilm of N. commune is rather hygroscopic and tends to store water at lower humidity values. Survival tests showed that a large proportion of the Alphaproteobacteria dominated microbiota associated to N. commune is very desiccation tolerant and water uptake from saturated NaCl solutions (either by direct uptake of brine or adsorption of humidity) did not enhance recultivability in long-time desiccated samples. Still, a minor part can grow under highly saline conditions. However, the salinity level, although unfavourable for the host organism, might be for parts of the heterotrophic microbiota no serious hindrance for growing in salty Mars-like environments.

Protection of cyanobacterial carotenoids' Raman signatures by Martian mineral analogues after high‐dose gamma irradiation

“…Cyanobacteria are also known to have a higher water storage capacity than algae, especially in lichen photobionts, as they can store large amounts in their extracellular polymeric substances matrices and thus remain photosynthetically active at lower relative humidity values . Moreover, Nostoc commune biofilms showed a superior ability to store water when compared with the lichen Xanthoria elegans , which is constituted of an algal photobiont . High moisture absorption and retention capacities constitute a clear adaptive strategy of cyanobacteria to cope with hyperarid conditions where water is only temporary available.…”

“…The higher water content of the P‐MRS cyanobacteria pellets could therefore explain the more heterogeneous preservation of carotenoid Raman signal at low gamma ray doses but do not seem to be significant at high doses. Additionally, Nostoc commune biofilms have been shown to be less hydrophilic than montmorillonite, which has similar water sorption properties to gypsum . The hydrophilic properties of both mineral mixtures could therefore provide an enhanced protection against radiation‐induced damages due to the present ionization of water molecules.…”

Life in a Droplet: Microbial Ecology in Microscopic Surface Wetness

“…Intermittent deliquescent microscopic wetness was shown to support microbial life and photosynthesis in the Atacama Desert (Navarro-González et al, 2003;Warren-Rhodes et al, 2006;Davila et al, 2008Davila et al, , 2010Davila et al, , 2013Gómez-Silva, 2018). Several bacterial species were shown to have the ability to survive in deliquescent salts of Mars-analog environment (Jänchen et al, 2016;Nuding et al, 2017;Heinz et al, 2019;Stevens et al, 2019;Hallsworth, 2020). The limits of water activity to support life have also been explored (Stevenson et al, 2015a,b).…”

Axenic Biofilm Formation and Aggregation by Synechocystis sp. Strain PCC 6803 Are Induced by Changes in Nutrient Concentration and Require Cell Surface Structures

“…However, compared to the wealth of axenic heterotrophic biofilm studies, progress for axenic phototrophs has been limited because the available biofilm assays are relatively slow, and model organisms for axenic phototrophic biofilm formation have not been established. As a result, axenic biofilm formation by phototrophs remains poorly understood relative to the prominence of phototrophic biofilms in the earliest fossil record (5)(6)(7)114) and to their importance in global nutrient cycling (8)(9)(10)(11), astrobiology and space exploration (12)(13)(14), and biofuel production (15)(16)(17).…”