Phylogeny and Properties of New Pseudomonas spp. from the Rhizosphere of Southern Ural Leguminous Plants

Since many members of the genus Pseudomonas have growth-stimulating properties and are able to carry out biological control, they may be used to develop biopreparations and environmentally friendly fertilizers. The goal of the present work was to isolate new Pseudomonas strains from the rhizosphere of leguminous plants of the Southern Ural and to study their economically useful properties. Molecular genetic analysis of these bacterial strains was carried out. According to the results on the nucleotide sequences of the 16S rRNA and rpoD genes, four Pseudomonas strains were identified. One of them, Pseudomonas sp. OBA 2.4.1, was closest to the type strain of Pseudomonas fluorescence in terms of the homology of the studied genes, and the strains of Pseudomonas sp. OBA 2.9, GOR 4.17, and STA 3 were most closely related to the type strain of Pseudomonas koreensis. Further studies revealed that all the studied bacteria were capable of forming biofilms on both inert surfaces and plant roots and exhibited antagonistic activity against phytopathogenic fungi. Moreover, three strains were shown to dissolve inorganic phosphate. Treatment of red clover seeds with Pseudomonas sp. OBA 2.4.1 resulted in an 18% increase in seed germination and a 21% increase in dry plant biomass relative to the control. The data obtained allow us to consider the studied microorganisms as bacteria that can have a positive effect on plant growth and development.