We performed studies of morphological diversity, abundance, size spectrum of autochtonous bacteriophages using a modern method of transmission electronic microscopy isolated from different biotops of Lake Baikal. Molecular biological studies of Baikalian phages revealed a unique nature of some of them. We performed as well bioinformational analysis and deciphered the complete genome of a giant phage from the family Myoviridae, contaminating Pseudomonas aeruginosa – PaBG using modern new generation sequence methods (MiSeq, Illumina).