Search for putative complete and near-complete genomes of DNA-containing viruses in metagenomes obtained from the Lake Baikal

Abstract

The paper presents the analysis of putatively complete and near-complete genomes of bacteriophages extracted from metagenomic data obtained from DNA samples isolated from Lake Baikal water using modern bioinformatic programs. A total of 73 sequences with lengths ranging from 13.8 kb to 163.7 kb belonging to phages of the Caudoviricetes class were identified. Two contigs belonging putatively to cyanophages with lengths of 36.8 kb and 163.7 kb were detected, and in the latter one an ORF with a length of 159 amino acid residues similar to the small heat shock protein (Hsp20) was identified. Analysis of the amino acid sequences identified in the assembled bacteriophage genomes using the PHROG database revealed that 27.5% of them have an unknown function, while the majority of those with similarity to known ones (23.7%) belong to the category “DNA, RNA and nucleotide metabolism”. A number of accessory metabolic genes (AMGs) were also detected in the assembled genomes: nadM, cysC, cobS, galE, cobT, etc. Most of the sequences with similarity to sequences from the IMG/VR database (89.6%) corresponded to sequences obtained from freshwater bodies.