Changes in membrane fatty acids of a halo-psychrophile exposed to magnesium perchlorate and low temperatures: Implications for Mars habitability

The presence of perchlorate salts in aqueous solutions bears two opposite effects on habitability. On the one hand, trigger a decrease freezing point solutions, resulting stable at subzero temperatures, thereby widening habitable conditions for potential microbial life. other perchlorates solution imposes significant osmotic stress that compromises integrity cell membranes, restricting same environment. Here we investigated survivability and changes composition membrane fatty acids (FAs) bacterium Rhodococcus sp . JG-3 cells under warm (20°C), cold (4°C), temperatures (?10°C ?16°C), (8 wt% 16 wt%) absence magnesium (Mg(ClO 4 ) 2 ). Bacterial decreased with decreasing temperature perchlorate. However, sp. was able to tolerate up 8 Mg(ClO ?16°C. medium concentration total FAs, likely due destabilization molecules by chaotropic effect anion. At maximum (both perchlorate), FAs changed, i.e., increased relative abundance saturated (SFAs) over unsaturated (UFAs) or branched (BFAs). These proportion types may be physiological response during cooling, aimed improve lipid stability. Interestingly, acid (i.e., SFAs, UFAs BFAs) when simultaneously exposed similar following alone, suggesting either both triggered dominated other. Our findings contribute understand adaptation extremophilic microorganisms polyextreme conditions, such as those existing Martian subsurface today and/or past, which include documented ancient sediments global temperatures.