Estimate of the diversity of viral and bacterial assemblage in the coastal water of Lake Baikal.

In this study, we analysed the diversity and composition of double-stranded DNA viral and bacterial communities within the sample of surface coastal water of Southern Baikal through metagenomics and deep sequencing of the 16S ribosomal RNA gene, respectively. The 16S rRNA gene analysis has revealed 14 phyla and dominance of the 'Actinobacteria' (43.6%), 'Proteobacteria' (25.2%) and 'Bacteroidetes' (11.5%). The bacterial composition was similar to that obtained previously in Lake Baikal littoral zone. Out of 1 030 169 processed virome reads, 37.4% of sequences (385 421) were identified as viral; 15.1% were identified as nonviral and related to the domains Eukarya, Bacteria and Archaea; and 47.5% had no matches in the databases. The identified virotypes belonged to different families and were predicted to infect a wide range of organisms, from bacteria to mammals. Six families (Myoviridae, Poxviridae, Mimiviridae, Siphoviridae, Phycodnaviridae and Podoviridae) were dominant accounting for more than 90% of the identified sequences (48.3%, 17.4%, 8.3%, 6.8%, 5.8% and 4.1%, respectively). In contrast to other freshwater systems, high percentage of the Poxviridae and Mimiviridae was recorded in the water sample of Lake Baikal.