RT Journal Article
SR Electronic
T1 Hyperdiverse archaea near life limits at the polyextreme geothermal Dallol area
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 658211
DO 10.1101/658211
A1 Jodie Belilla
A1 David Moreira
A1 Ludwig Jardillier
A1 Guillaume Reboul
A1 Karim Benzerara
A1 José M. López-García
A1 Paola Bertolino
A1 Ana I. López-Archilla
A1 Purificación López-García
YR 2019
UL http://biorxiv.org/content/early/2019/07/28/658211.abstract
AB Microbial life has adapted to various individual extreme conditions; yet, organisms simultaneously adapted to very low pH, high salt and high temperature are unknown. We combined environmental 16S/18S rRNA-gene metabarcoding, cultural approaches, fluorescence-activated cell sorting, scanning electron microscopy and chemical analyses to study samples along such unique polyextreme gradients in the Dallol-Danakil area (Ethiopia). We identify two physicochemical barriers to life in the presence of surface liquid water defined by: i) high chaotropicity-low water activity in Mg2+/Ca2+-dominated brines and ii) hyperacidity-salt combinations (pH~0/ NaCl-dominated salt-saturation) When detected, life was dominated by highly diverse ultrasmall archaea widely distributed across phyla with and without previously known halophilic members. We hypothesize that high cytoplasmic K+-level was an original archaeal adaptation to hyperthermophily, subsequently exapted during multiple transitions to extreme halophily. We detect active silica encrustment/fossilization of cells but also abiotic biomorphs of varied chemistry. Our work helps circumscribing habitability and calls for cautionary interpretations of morphological biosignatures on Earth and beyond.