New Data on the Phylogenetic Diversity of Bacteria and Archaea in Marls of the Verkhnekamsk Salt Deposit (Russia)

Abstract

The phylogenetic diversity of archaea and bacteria was investigated for the first time in marl samples of the Verkhnekamsk salt deposit of Perm Krai (Russia). Two libraries of 16S rRNA genes from the marl sample (depth of 70.5 m) obtained by molecular genetic methods (cloning of 16S rRNA genes, RFLP analysis and sequencing) were distributed in 3 archaeal OTUs (80 clones) and 11 bacterial OTUs (86 clones). Phylogenetic analysis showed a low diversity of Archaea, closely related to the Thaumarchaeota phylum (phylogenetic cluster Marine Group I). Thereto, all archaeal OTUs were similar in the 16S rRNA gene with an uncultured archaeal clone isolated from groundwater of the Permian period. Molecular phylogeny revealed that bacterial diversity was presented by the phyla Proteobacteria, Actinobacteria and Acidobacteria. The dominant phylum Proteobacteria (75.54% of total bacterial clones) included 7 OTU, belonging to the classes Alpha-, Beta- and Gammaproteobacteria, most of which (44.19%) refer to the representatives of the genus Pseudomonas (class Gammaproteobacteria). Up to 12% of total bacterial clones may represent novel taxonomic units. This study indicated the occurrence and diversity of endolithic bacteria and archaea in the marls of the salt deposit, the presence of some of them was recorded for the first time in the saline endolithic microbial communities.