Diversity of <i>Archaea</i> in Bottom Sediments of the Discharge Areas With Oil- and Gas-Bearing Fluids in Lake Baikal

<p>Using massively parallel sequencing (the Roche 454 platform) we have studied the diversity of archaeal 16S rRNA gene sequences in oxic and anoxic sediments at six sites in Lake Baikal with oil- and gas-bearing fluids discharge. Archaeal communities appeared to be represented mainly by five phyla: <i>Euryarchaeota, Crenarchaeota, Thaumarchaeota, Bathyarchaeota</i> (miscellaneous Crenarchaeotic group), and <i>Woesearchaeota</i> (deep sea hydrothermal vent group 6). Among them we detected sequences of methanogens of the orders <i>Methanomicrobiales, Methanosarsinales, Methanococcales</i>, as well as representatives of the following uncultured archaeal lineages: Group C3, Marine Benthic Group D, and Terrestrial Miscellaneous Group. We have also identified sequences of ammonia-oxidizing archaea of the phyla <i>Crenarchaeota</i> and <i>Thaumarchaeota</i>. Phylogenetic analysis showed the presence ANME-2d-related sequences. However, the analysis of <i>mcr</i>A genes libraries has not revealed typical representatives of ANME groups. Comparison of amplicon libraries 16S rRNA gene fragments from different samples proved the widespread presence of previously detected Baikal archaeal lineages, which are members of the phylum <i>Crenarchaeota</i> and <i>Thaumarchaeota</i> (formerly Group C3 of <i>Crenarchaeota</i>).</p