Prokaryotic community structure in photosynthetic biofilms from extreme acidic streams, Río Tinto (SW, Spain) Authors Virginia Souza-Egipsy Centro de Astrobiología (INTA-CSIC) Elena González-Toril Centro de Astrobiología (INTA-CSIC) Erik Zettler Sea Education Association; Centro de Biología Molecular (UAM-CSIC). Universidad Autonoma de Madrid Linda Amaral-Zettler Marine Biological Laboratory Angeles Aguilera Centro de Astrobiología (INTA-CSIC) Ricardo Amils Centro de Astrobiología (INTA-CSIC); Centro de Biología Molecular (UAM-CSIC). Universidad Autonoma de Madrid Keywords: 16S rRNA, FISH, SEM, Biofilms, Acidic Abstract Four algal photosynthetic biofilms were collected from the Río Tinto (SW Spain) at four localities: AG, Euglena and Pinnularia biofilms; ANG, Chlorella and Pinnularia biofilms; RI, Cyanidium and Dunaliella biofilms; and CEM, Cyanidium, Euglena and Pinnularia biofilms. Community composition and structure were studied by a polyphasic approach consisting of 16S rRNA analysis, scanning electron microscopy by back-scattered electron detection mode (SEM-BSE), and fluorescence in-situ hybridization (FISH). Acidophilic prokaryotes associated with algal photosynthetic biofilms included sequences related to the Alpha-, Beta-, and Gammaproteobacteria (phylum Proteobacteria) and to the phyla Nitrospira, Actinobacteria, Acidobacteria and Firmicutes. Sequences from the Archaea domain were also identified. No more than seven distinct lineages were detected in any biofilm, except for those from RI, which contained fewer groups of Bacteria. Prokaryotic communities of the thinnest algal photosynthetic biofilms (<100 μm) were more related to those in the water column, including Leptospirillum populations. In general, thick biofilms (>200 μm) generate microniches that could facilitate the development of less-adapted microorganisms (coming from the surrounding environment) to extreme conditions, thus resulting in a more diverse prokaryotic biofilm. [Int Microbiol 2008; 11(4):251-260] Author Biographies Virginia Souza-Egipsy, Centro de Astrobiología (INTA-CSIC) Centro de Astrobiología (INTA-CSIC) Elena González-Toril, Centro de Astrobiología (INTA-CSIC) Centro de Astrobiología (INTA-CSIC) Erik Zettler, Sea Education Association; Centro de Biología Molecular (UAM-CSIC). Universidad Autonoma de Madrid Sea Education Association; Centro de Biología Molecular (UAM-CSIC). Universidad Autonoma de Madrid Linda Amaral-Zettler, Marine Biological Laboratory Marine Biological Laboratory Angeles Aguilera, Centro de Astrobiología (INTA-CSIC) Centro de Astrobiología (INTA-CSIC) Ricardo Amils, Centro de Astrobiología (INTA-CSIC); Centro de Biología Molecular (UAM-CSIC). Universidad Autonoma de Madrid Centro de Astrobiología (INTA-CSIC); Centro de Biología Molecular (UAM-CSIC). Universidad Autonoma de Madrid Downloads PDF Published 2010-09-21 Issue Vol. 11 No. 4 (2008) Section Research Articles License Submission of a manuscript to International Microbiology implies: that the work described has not been published before, including publication in the World Wide Web (except in the form of an Abstract or as part of a published lecture, review, or thesis); that it is not under consideration for publication elsewhere; that all the coauthors have agreed to its publication. The corresponding author signs for and accepts responsability for releasing this material and will act on behalf of any and all coauthors regarding the editorial review and publication process.If an article is accepted for publication in International Microbiology, the authors (or other copyright holder) must transfer to the journal the right–not exclusive–to reproduce and distribute the article including reprints, translations, photographic reproductions, microform, electronic form (offline, online) or any other reproductions of similar nature. Nevertheless, all article in International Microbiology will be available on the Internet to any reader at no cost. The journal allows users to freely download, copy, print, distribute, search, and link to the full text of any article, provided the authorship and source of the published article is cited. The copyright owner's consent does not include copying for new works, or resale. In these cases, the specific written permission of International Microbiology must first be obtained.Authors are requested to create a link to the published article on the journal's website. The link must be accompanied by the following text: "The original publication is available on LINK at <http://www.im.microbios.org>. Please use the appropiate URL for the article in LINK. Articles disseminated via LINK are indexed, abstracted, and referenced by many abstracting and information services, bibliographic networks, subscription agencies, library networks, and consortia.