title: Manganese-Cycling Microbial Communities Inside Deep-Sea Manganese Nodules.
abstract: Polymetallic nodules (manganese nodules) have been formed on deep sea sediments over millions of years and are currently explored for their economic potential, particularly for cobalt, nickel, copper, and manganese. Here we explored microbial communities inside nodules from the northeastern equatorial Pacific. The nodules have a large connected pore space with a huge inner surface of 120 m(2)/g as analyzed by computer tomography and BET measurements. X-ray photoelectron spectroscopy (XPS) and electron microprobe analysis revealed a complex chemical fine structure. This consisted of layers with highly variable Mn/Fe ratios (<1 to >500) and mainly of turbostratic phyllomanganates such as 7 and 10 Å vernadites alternating with layers of Fe-bearing vernadite (δ-MnO2) epitaxially intergrown with amorphous feroxyhyte (δ-FeOOH). Using molecular 16S rRNA gene techniques (clone libraries, pyrosequencing, and real-time PCR), we show that polymetallic nodules provide a suitable habitat for prokaryotes with an abundant and diverse prokaryotic community dominated by nodule-specific Mn(IV)-reducing and Mn(II)-oxidizing bacteria. These bacteria were not detected in the nodule-surrounding sediment. The high abundance and dominance of Mn-cycling bacteria in the manganese nodules argue for a biologically driven closed manganese cycle inside the nodules relevant for their formation and potential degradation.
authors.affiliation: †Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, 30655 Hannover, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Blöthe
authors.affiliation: †Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, 30655 Hannover, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Wegorzewski
authors.affiliation: ‡Leibniz Institute for Applied Geophysics, Stilleweg 2, 30655 Hannover, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Müller
authors.affiliation: §Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, 01069 Dresden, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Simon
authors.affiliation: †Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, 30655 Hannover, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kuhn
authors.affiliation: †Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, 30655 Hannover, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Schippers
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000378:metabolism; D001673:Biodegradation, Environmental; D017753:Ecosystem; D008345:Manganese / Q000378:metabolism*; D064307:Microbiota; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D010802:Phylogeny; D016062:Porosity; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D012336:RNA, Ribosomal, 16S; D008345:Manganese