Population density and taxonomic composition of bacterial nanoforms in soils of Russia

Abstract

The population density, physiological state, and taxonomic composition of bacterial nanoforms were first studied in soils of Russia. It was demonstrated with the help of fluorescent microscopy that the populations of nanoforms in the studied soils are very high and comprise tens and hundreds of millions of cells per 1 g of soil. The portion of cells with undamaged cell membranes was significantly higher in the nanoforms (95–98%) than in the cells of common size (about 50%), and this fact suggests the viability of the nanoforms. The taxonomic diversity of the nanoforms is great; the representatives of the main phylogenetic groups widespread in the soils were found among the nanoforms, namely, Archaea, Actinobacteria, Cytophaga, and Proteobacteria. The results allow assuming that the transformation of the cells into nanoforms is a relatively common event in the life of soil bacteria, allowing them to remain viable under unfavorable conditions and participate actively in soil processes.