title: Extremely halophilic microbial communities in anaerobic sediments from a solar saltern.
abstract: The prokaryotic communities inhabiting hypersaline sediments underlying a crystallizer pond of a Mediterranean solar saltern have been studied in a polyphasic approach including 16S rRNA and dsrAB gene libraries analysis [the last encoding for dissimilatory (bi)sulfite reductase], most probable number of cultivable counts, and metabolic measurements of sulfate reduction. The samples studied here represent one of the most hypersaline anoxic environments sampled worldwide that harbour a highly diverse microbial community different from those previously reported in other hypersaline sediments. Both bacterial and archaeal types are present but, contrarily to the overlying brine system, the former dominates. Molecular analyses indicated that the bacterial fraction is highly diverse and mostly composed by groups related to sulfate-reducing bacteria (SRB). In good agreement with this, sulfate-reducing activity was detected in the sediment, as well as the metabolic diversity within SRB (as indicated by the use of different electron donors in enrichments). On the other hand, the archaeal fraction was phylogenetically homogeneous and, surprisingly, strongly affiliated with the MBSl-1 candidate division, an euryarchaeotal group only reported in deep-sea hypersaline anoxic basins of the Western Mediterranean, for which a methanogenic metabolism was hypothesized. The hypersaline studied samples constitute a valuable source of new prokaryotic types with metabolisms adapted to the prevalent in situ extreme conditions.
authors.affiliation: Marine Microbiology Group, Dptm, Recursos Naturals, Institut Mediterrani d'Estudis Avançats, IMEDEA-CSIC. C/ Miquel Marqués, 21, 07190 Esporles, Illes Balears, Spain. Departamento de Fisiología, Genética y Microbiología, and IMEM, Universidad de Alicante, Apartado 99, 03080 Alicante, Spain. Institute for Environmental Geosciences, University of Basel, Bernoullistrasse, 30, 4056 Basel, Switzerland. Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: Arantxa
authors.initials: A
authors.lastname: López-López
authors.forename: Pablo
authors.initials: P
authors.lastname: Yarza
authors.forename: Michael
authors.initials: M
authors.lastname: Richter
authors.forename: Ana
authors.initials: A
authors.lastname: Suárez-Suárez
authors.forename: Josefa
authors.initials: J
authors.lastname: Antón
authors.forename: Helge
authors.initials: H
authors.lastname: Niemann
authors.forename: Ramón
authors.initials: R
authors.lastname: Rosselló-Móra