The microbiological investigation of microbial communities of the littoral zone of Lake Baikal showed that during cultivation on media which differ in the content of organic and mineral components, the maximum number of heterotrophs was found on poor medium (NSY+), whereas the minimal values - on rich medium (TSA). The diversity of dominant of heterotrophs, identified via 16S rDNA sequencing, represented the following genera: Acinetobacter, Arthrobacter, Enhydrobacter, Gulbenkiania, Klebsiella, Massilia, Methylobacterium, Pseudomonas, Sphingomonas and Staphylococcus. Factors affected on the content of heterotrophic microbial communities in the littoral zone of the lake are discussed.