Phylogenetic Diversity of Winter Bacterioplankton of Eutrophic Siberian Reservoirs as Revealed by 16S rRNA Gene Sequence

Using 16S rRNA gene sequence analyses we investigated the bacterial diversity of winter bacterioplankton of two eutrophic Siberian reservoirs. These reservoirs show similarity in phytoplankton community composition in spring and autumn but tend to differ in summer in exhibiting cyanobacterial bloom. Forty-eight unique partial 16S RNA gene sequences retrieved from two libraries were mostly affiliated with the class Actinobacteria, b subdivision of the class Proteobacteria, and the phylum Cytophaga–Flavobacterium–Bacteroides. The clone library of the pond exhibiting summer cyanobacterial bloom showed more diversity in sequence composition. A significant number of bacterial 16S rRNA gene clones were closely related to freshwater bacteria previously found in different aquatic ecosystems. This finding confirms the assumption that some bacterial clades are globally distributed.