RESUMO
Strategies for life adaptation to extreme environments often lead to novel solutions. As an example of this assertion, here we describe the first species of the well-known genus of green unicellular alga Dunaliella able to thrive in a subaerial habitat. All previously reported members of this microalga are found in extremely saline aquatic environments. Strikingly, the new species was found on the walls of a cave located in the Atacama Desert (Chile). Moreover, on further inspection we noticed that it grows upon spiderwebs attached to the walls of the entrance-twilight transition zone of the cave. This peculiar growth habitat suggests that this Dunaliella species uses air moisture condensing on the spiderweb silk threads as a source of water for doing photosynthesis in the driest desert of the world. This process of adaptation recapitulates the transition that allowed land colonization by primitive plants and shows an unexpected way of expansion of the life habitability range by a microbial species.
Assuntos
Biopolímeros/análise , Clorófitas/crescimento & desenvolvimento , Clima Desértico , Aranhas/fisiologia , Adaptação Fisiológica , Animais , Chile , Clorófitas/classificação , Clorófitas/genética , Clorófitas/metabolismo , Clorófitas/ultraestrutura , DNA de Plantas/análise , Ecossistema , Umidade , Microscopia Eletrônica de Varredura , Fotossíntese , FilogeniaRESUMO
Caves offer a stable and protected environment from harsh and changing outside prevailing conditions. Hence, they represent an interesting habitat for studying life in extreme environments. Here, we report the presence of a member of the ancient eukaryote red algae Cyanidium group in a coastal cave of the hyperarid Atacama Desert. This microorganism was found to form a seemingly monospecific biofilm growing under extremely low photon flux levels. Our work suggests that this species, Cyanidium sp. Atacama, is a new member of a recently proposed novel monophyletic lineage of mesophilic "cave" Cyanidium sp., distinct from the remaining three other lineages which are all thermo-acidophilic. The cave described in this work may represent an evolutionary island for life in the midst of the Atacama Desert.