INVESTIGADORES
AGUILAR Orlando Mario
artículos
Título:
The discovery of stromatolites developing at 3570 m above sea level in a high-altitude
Autor/es:
M. E. FARÍAS1§, N. RASCOVAN, D. M. TONEATTI, V. H. ALBARRACÍN. M. VAZQUEZ. O. M. AGUILAR, POLERECKY
Revista:
PLOS ONE
Editorial:
PUBLIC LIBRARY SCIENCE
Referencias:
Lugar: San Francisco; Año: 2012
ISSN:
1932-6203
Resumen:
We describe stromatolites forming at an altitude of 3570 m at the shore of a volcanic
lake Socompa, Argentinean Andes. The water at the site of stromatolites formation is
alkaline, hypersaline, rich in inorganic nutrients, very rich in arsenic, and warm (20-24
ºC) due to a hydrothermal input. The stromatolites do not lithify, but form broad,
rounded and low-domed bioherms dominated by diatom frustules and aragonite microcrystals
agglutinated by extracellular substances. In comparison to other modern
stromatolites, they harbour an atypical microbial community characterized by highly
abundant representatives of Deinococcus-Thermus, Rhodobacteraceae,
Desulfobacterales and Spirochaetes. Additionally, a high proportion of the sequences
that could not be classified at phylum level showed less than 80% identity to the best
hit in the NCBI database, suggesting the presence of novel distant lineages. The
primary production in the stromatolites is generally high and likely dominated by
Microcoleus sp.. Through negative phototaxis, the location of these cyanobacteria in
the stromatolites is controlled by UV light, which greatly influences their photosynthetic
activity. Diatoms, dominated by Amphora sp., are abundant in the anoxic, sulfidic and
essentially dark parts of the stromatolites. Although their origin in the stromatolites is
unclear, they are possibly an important source of anaerobically degraded organic
matter that induces in situ aragonite precipitation. To the best of our knowledge, this is
so far the highest altitude with documented actively forming stromatolites. Their
generally rich, diverse and to a large extent novel microbial community likely harbours
valuable genetic and proteomic reserves, and thus deserves active protection.
Furthermore, since the stromatolites flourish in an environment characterized by a
multitude of extremes, including high exposure to UV radiation, they can be an
excellent model system for studying microbial adaptations under conditions that, at
least in part, resemble those during the early phase of life evolution on Earth.