Microorganisms inhabiting the endo- and rhizosphere of Hedysarum zundukii (Fabaceae) endemic to the Baikal region

Bacteria provide plants with additional resistance to adverse environmental factors, such as the lack of soil nutrients, anthropogenic pollution, the presence of phytopathogens, etc. The search for valuable biotechnological strains should be conducted among microorganisms associated with plants growing under unfavorable conditions. The present study aims to isolate and characterize microorganisms inhabiting the endo- and rhizosphere of Hedysarum zundukii, a local endemic of the Olkhon region (Olkhonsky District, Irkutsk Oblast). A total of 88 microbial strains were isolated, with Gram-positive microorganisms predominating in both the rhizo- and endosphere. In the rhizosphere, the vast majority of strains were found to belong to actinomycetes. Of the 25 identified isolates, four belong to the Rhizobiaceae family. The Phyllobacterium zundukense rhizobacterium was previously described as part of the microbiome of root nodules in Oxytropis triphylla also growing in this region. Its detection in the rhizosphere soil of H. zundukii suggests that this microorganism is associated with different legume species rather than with a single host. Of particular interest are the strains of Actinomycetia, as well as Lysobacter sp. and Variovorax paradoxus, which are promising for further study as producers of biologically active compounds, stimulators of plant growth and development, or pollutant degraders. Thus, isolates from both the rhizosphere and endosphere of H. Zundukii may possess traits useful for biotechnology and require further study.