New communities of large filamentous sulfur bacteria in the eastern South Pacific Autors/ores Víctor A. Gallardo Department of Oceanography, University of Concepción, Concepción, Chile Carola Espinoza Department of Oceanography, University of Concepción, Concepción, Chile Paraules clau: Thioploca spp., Beggiatoa spp., Thiomargarita, filamentous bacteria, large sulfur bacteria, eastern South Pacific, anoxic environments, ENSO cycle Resum New complex communities of morphologically diverse and sometimes abundant large, multicellular, filamentous bacteria were discovered in the oxygen-deficient, organically laden, shelf sediments under the oxygen minimum zone off the coast of the eastern Pacific, i.e., off the coasts of central and northern Chile; central and northern Perú; Roca Redonda, Galápagos Archipielago, Ecuador; and off the Pacific coasts of Panamá and Costa Rica. Similar microbial communities were also observed in the reduced layer of a muddy-sand beach adjacent to a mangrove swamp on Coiba Island, Pacific Panamá, and in the organically laden bottom underneath a salmon culture pen in southern Chile (region X). Of varying morphology, the diameters of the bacteria range from <1 to <10 μm, and their lengths from around 10 μm to usually several hundreds but at times several thousands of micrometers. The new filamentous bacterial component is at least one order of magnitude smaller than the also multicellular “megabacteria” Thioploca spp. and Beggiatoa spp., and is collectively referred to as “macrobacteria”. A recent review only mentioned a few of these free-living filamentous bacteria, remarking on their scarcity despite the obvious advantages of a large size. This prokaryote size-window has been rarely investigated optically by researchers; thus, assemblages that appear to have had world-wide distribution probably since pre-Cambrian times have been overlooked. [Int Microbiol 2007; 10(2):97-102] Biografies de l'autor/a Víctor A. Gallardo, Department of Oceanography, University of Concepción, Concepción, Chile Department of Oceanography, University of Concepción, Concepción, Chile Carola Espinoza, Department of Oceanography, University of Concepción, Concepción, Chile Department of Oceanography, University of Concepción, Concepción, Chile Descàrregues PDF (English) Publicat 2010-01-26 Número Vol. 10 Núm. 2 (2007) Secció Articles Llicència 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.