A Rich Morphological Diversity of Biosaline Drying Patterns Is Generated by Different Bacterial Species, Different Salts and Concentrations: Astrobiological Implications

摘要

Biosaline formations (BSFs) are complex self-organized biomineral patterns formed by ‘‘hibernating’’ bacteriaas the biofilm that contains them dries out. They were initially described in drying biofilms of Escherichia colicells + NaCl. Due to their intricate 3-D morphology and anhydrobiosis, these biomineralogical structures are ofgreat interest in astrobiology. Here we report experimental data obtained with various alkali halide salts (NaF,NaCl, NaBr, LiCl, KCl, CsCl) on BSF formation with E. coli and Bacillus subtilis bacteria at two salineconcentrations: 9 and 18 mg/mL. Our results indicate that, except for LiCl, which is inactive, all the saltsassayed are active during BSF formation and capable of promoting the generation of distinctive drying patternsat each salt concentration. Remarkably, the BSFs produced by these two bacterial species produce characteristicarchitectural hallmarks as the BSF dries. The potential biogenicity of these biosaline drying patterns is studied,and the astrobiological implications of these findings are discussed