A study on the taxonomy of soil amoebas from Caspian plague foci based on an analysis of ribosomal operon sequences

The results of a study on the taxonomy and quantitative abundance of free-living amoebas in soil samples from the Russian plague foci of the Northwestern Caspian steppe, the Caspian sand, and the Volga-Ural steppe are presented. Amoebas of the Willaertia and Hartmanella genera, as well as representatives of myxomycetes, were isolated from samples. From these, amoebas of the Acanthamoeba genus predominated and could be as abundant as 300000 cells per 1 g of soil. Sequencing of the18S rRNA gene region showed that Acanthamoeba from the Volga-Ural steppe focus belonged to the A. castellanii species. Phylogenetic analysis confirmed that amoebas from two other Caspian foci belonged to the species of Acanthamoeba spp.