Study of ultramicrobacteria (Nanoforms) in soils and subsoil deposits by electron microscopy

The use of multiple centrifuging and filtration of water suspensions from different soils and subsoil deposits allowed revealing the ultrafine forms (nanosized, nanoforms) of bacteria. In the soils studied, the number of bacteria obtained by filtration using 0.2-??m filters was 20?C300 mln cells in 1 g soil; the share of these bacteria of their total population in the natural soils reached 5% and was higher (up to 15%) in the polluted urban soils. The study of bacterial nanoforms in situ by the methods of scanning and transmission microscopy has shown the presence of dividing cells, which testifies to their viability. The cells without signs of division were similar in their ultrastructural characteristics to dormant forms of nonspore-forming bacteria. They were observed in permafrost deposits. The data obtained attest that the bacterial nanoforms are widespread in soils and subsoil deposits. According to their morphological and cytological characteristics, they are represented by both active and dormant forms to survive unfavorable conditions.