title: Insights into the genomes of archaea mediating the anaerobic oxidation of methane.
abstract: The anaerobic oxidation of methane is a globally significant process which is mediated by consortia of yet uncultivated methanotrophic archaea (ANME) and sulfate-reducing bacteria. In order to gain deeper insights into genome characteristics of the different ANME groups, large-insert genomic libraries were constructed using DNA extracted from a methanotrophic microbial mat growing in the anoxic part of the Black Sea, and from sediments above gas hydrates at the Hydrate Ridge off the coast of Oregon. Analysis of these fosmid libraries with respect to archaeal 16S rRNA gene diversity revealed a single ANME-1b ribotype for the Black Sea libraries, whereas the sequences derived from the Hydrate Ridge library phylogenetically affiliated with the ANME-2a, ANME-2c and ANME-3 group. Genome walking for ANME-1b resulted in a contiguous 155 kb composite genome fragment. The comparison of a set of four genomic fragments belonging to the different ANME groups revealed differences in the rRNA operon structure and the average G+C content, with the ANME-2c contig showing the highest divergence within the set. A detailed analysis of the ANME contigs with respect to genes putatively involved in the anaerobic oxidation of methane led to the identification of: (i) a putative N5,N10-methenyltetrahydromethanopterin cyclohydrolase gene, (ii) a gene cluster supposedly encoding a novel type of heterodisulfide reductase/dehydrogenase complex and (iii) a gene cluster putatively encoding a new type of CO dehydrogenase/acetyl-CoA synthase enzyme complex.
authors.affiliation: Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, 28359 Bremen, Germany. ameyerdi@mpi-bremen.de
authors.forename: Anke
authors.initials: A
authors.lastname: Meyerdierks
authors.forename: Michael
authors.initials: M
authors.lastname: Kube
authors.forename: Thierry
authors.initials: T
authors.lastname: Lombardot
authors.forename: Katrin
authors.initials: K
authors.lastname: Knittel
authors.forename: Margarete
authors.initials: M
authors.lastname: Bauer
authors.forename: Frank Oliver
authors.initials: FO
authors.lastname: Glöckner
authors.forename: Richard
authors.initials: R
authors.lastname: Reinhardt
authors.forename: Rudolf
authors.initials: R
authors.lastname: Amann
mesh_terms: D000595:Amino Acid Sequence; D000693:Anaerobiosis; D001105:Archaea / Q000235:genetics* / Q000378:metabolism; D001482:Base Composition; D020745:Genome, Archaeal; D019015:Geologic Sediments / Q000382:microbiology; D008697:Methane / Q000378:metabolism*; D008969:Molecular Sequence Data; D005810:Multigene Family; D009792:Oceans and Seas; D009876:Operon; D009922:Oregon; D010084:Oxidation-Reduction; D019642:RNA, Archaeal; D012335:RNA, Ribosomal; D012426:Russia; D016415:Sequence Alignment; D014871:Water Microbiology
chemical_list: D019642:RNA, Archaeal; D012335:RNA, Ribosomal; D008697:Methane