title: Bacterial community in ancient Siberian permafrost as characterized by culture and culture-independent methods.
abstract: The microbial composition of ancient permafrost sediments from the Kolyma lowland of Northeast Eurasia was examined through culture and culture-independent approaches. These sediments have been continuously frozen for 5,000 to 2-3 million years. A total of 265 Bacteria 16S rRNA gene sequences were amplified from the permafrost total-community genomic DNA and screened by amplified ribosomal 16S rRNA restriction analysis. Members of three major lineages were found: gamma-Proteobacteria (mostly Xanthomonadaceae), Actinobacteria, and Firmicutes. We also determined partial 16S rRNA gene sequences of 49 isolates from a collection of 462 aerobes isolated from these sediments. The bacteria included Actinomycetales (Arthrobacter and Microbacteriaceae); followed by the Firmicutes (Exiguobacterium and Planomicrobium); the Bacteroidetes (Flavobacterium); the gamma-Proteobacteria (Psychrobacter); and the alpha-Proteobacteria (Sphingomonas). Both culture and culture-independent approaches showed the presence of high and low G+C Gram-positive bacteria and gamma-Proteobacteria. Some of the 16S rRNA gene sequences of environmental clones matched those of Arthrobacter isolates. Two-thirds of the isolates grew at -2.5 degrees C, indicating that they are psychroactive, and all are closely related to phylogenetic groups with strains from other cold environments, mostly commonly from Antarctica. The culturable and non-culturable microorganisms found in the terrestrial permafrost provide a prototype for possible life on the cryogenic planets of the Solar System.
authors.affiliation: Center for Microbial Ecology, Michigan State University, East Lansing, Michigan, USA.
authors.forename: Tatiana A
authors.initials: TA
authors.lastname: Vishnivetskaya
authors.forename: Maya A
authors.initials: MA
authors.lastname: Petrova
authors.forename: John
authors.initials: J
authors.lastname: Urbance
authors.forename: Monica
authors.initials: M
authors.lastname: Ponder
authors.forename: Craig L
authors.initials: CL
authors.lastname: Moyer
authors.forename: David A
authors.initials: DA
authors.lastname: Gilichinsky
authors.forename: James M
authors.initials: JM
authors.lastname: Tiedje
mesh_terms: D001419:Bacteria / Q000235:genetics; D003080:Cold Temperature; D005618:Fresh Water / Q000382:microbiology; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S; D012623:Seawater / Q000382:microbiology; D012800:Siberia; D012988:Soil Microbiology
chemical_list: D012336:RNA, Ribosomal, 16S