11 research outputs found
Connecting biodiversity and potential functional role in modern euxinic environments by microbial metagenomics
14 páginas, 7 figuras, 3 tablas.Stratified sulfurous lakes are appropriate environments for studying the links between composition
and functionality in microbial communities and are potentially modern analogs of anoxic conditions
prevailing in the ancient ocean. We explored these aspects in the Lake Banyoles karstic area (NE
Spain) through metagenomics and in silico reconstruction of carbon, nitrogen and sulfur metabolic
pathways that were tightly coupled through a few bacterial groups. The potential for nitrogen
fixation and denitrification was detected in both autotrophs and heterotrophs, with a major role for
nitrogen and carbon fixations in Chlorobiaceae. Campylobacterales accounted for a large
percentage of denitrification genes, while Gallionellales were putatively involved in denitrification,
iron oxidation and carbon fixation and may have a major role in the biogeochemistry of the iron
cycle. Bacteroidales were also abundant and showed potential for dissimilatory nitrate reduction to
ammonium. The very low abundance of genes for nitrification, the minor presence of anammox
genes, the high potential for nitrogen fixation and mineralization and the potential for chemotrophic
CO2 fixation and CO oxidation all provide potential clues on the anoxic zones functioning. We
observed higher gene abundance of ammonia-oxidizing bacteria than ammonia-oxidizing archaea
that may have a geochemical and evolutionary link related to the dominance of Fe in these
environments. Overall, these results offer a more detailed perspective on the microbial ecology of
anoxic environments and may help to develop new geochemical proxies to infer biology and
chemistry interactions in ancient ecosystems.This research was funded by Grants GOS-LAKES
CGL2009-08523-E and DARKNESS CGL2012-32747 to
EOC from the Spanish Office of Science (MINECO), from
financial support by the Beyster Family Fund of the San
Diego Foundation and the Life Technologies Foundation
to the J Craig Venter Institute, and the NASA Astrobiology
Institute to CLD.Peer reviewe