title: High Archaea diversity in Varvara hot spring, Bulgaria.
abstract: The phylogeny of the latest recognized domain, Archaea, is still complicated and it is largely based on environmental sequences. A culture independent molecular phylogenetic analysis revealed high Archaea diversity in a terrestrial hot spring, village Varvara, Bulgaria. A total of 35 archaeal operational taxonomic units (OTUs) belonging to three of the classified five Archaea phyla were identified. Most of the sequences were affiliated with the phylum Crenarchaeota (23), grouped in four branches. The rest of the sequences showed highest similarity to the unidentified archaeal clones (9), Euryarchaeota (2), and "Korarchaeota " (1). Eight (23%) of the sequenced 16S rDNAs didn't have known close relatives and represented new and diverse OTUs, four of them forming a new archaeal subgroup without close described sequences or culturable relatives. A sequence affiliated with "Korarchaeota " showed low similarity (90%) to the closest neighbor and both sequences formed unique branch in this phylum. Consequently, the constructed archaeal libraries are characterized by (1) high proportion of OTUs representing uncultivated archaeal phylogroups, (2) the abundance of novel phylotype sequences, (3) the presence of high proportions of Crenarchaeota phylotypes unrelated to cultivated organisms and (4) the presence of a sequence only distantly related to "Korarchaeota " phylum.
authors.affiliation: Institute of Microbiology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
authors.forename: Iva
authors.initials: I
authors.lastname: Ivanova
authors.forename: Ivan
authors.initials: I
authors.lastname: Atanassov
authors.forename: Dimitrina
authors.initials: D
authors.lastname: Lyutskanova
authors.forename: Margarita
authors.initials: M
authors.lastname: Stoilova-Disheva
authors.forename: Desislava
authors.initials: D
authors.lastname: Dimitrova
authors.forename: Iva
authors.initials: I
authors.lastname: Tomova
authors.forename: Anna
authors.initials: A
authors.lastname: Derekova
authors.forename: Galina
authors.initials: G
authors.lastname: Radeva
authors.forename: Velina
authors.initials: V
authors.lastname: Buchvarova
authors.forename: Margarita
authors.initials: M
authors.lastname: Kambourova
mesh_terms: D000595:Amino Acid Sequence; D001105:Archaea / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D001483:Base Sequence; D002031:Bulgaria; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D014644:Genetic Variation; D045482:Hot Springs / Q000382:microbiology*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012335:RNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D016415:Sequence Alignment; D014871:Water Microbiology
chemical_list: D004269:DNA, Bacterial; D012335:RNA, Ribosomal