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The aim of the study was to investigate the species diversity of AM fungi in different parts of the North Caucasus, biodiversity hotspot, the center of the world’s biological diversity. Samples were taken from 5 locations (stationary trial plots, STPs) in different ecosystems and at various altitudes. Identification was performed using sequencing for ITS1 and ITS2 regions, amplified with universal primers, Illumina MiSeq was employed. 19 genera of AM fungi were found on all STPs. The work did not reveal a correlation between the altitude and the species composition of AM fungi. At the same time, it should be assumed that a correlation could be found between the biodiversity of AM fungi and the type of ecosystem, which should be done in the future. The study shows it is necessary to use an analysis for both ITS regions, since the data obtained for each ITS region differ and complement each other. Analysis for the ITS2 region revealed 1.3 times more virtual taxa than for the ITS1, while the number of OTUs identified per species was similar for both regions. The highest biodiversity of AM fungi was found in STP #3 (with meadow flora). Only 4 species (Rhizophagus irregularis, R. intraradices, Paraglomus laccatum, and Claroideoglomus claroideum) were found on all five analyzed STPs. We found unexpectedly that with such a high biodiversity among the identified fungi, no different species were found in the Paraglomus genus, all the sequences of Paraglomus belonged to Paraglomus laccatum, whereas at least 9 species are distinguished in the genus by morphology. Further research will allow us to identify new strains of AM fungi, the efficiency of which may be higher than already studied ones. In the future this will make it possible to create more effective microbial biofertilizers for agriculture.

The objective of our research was to analyze the efficiency of identification of arbuscular mycorrhizal fungi (AMF) for 2 regions: ITS1 and ITS2 regions of AMF DNA isolated from the soils of the North Caucasus (Karachay-Cherkessia). For the first time the necessity of different AMF species identification using both ITS regions was revealed, but not one region. The research demonstrated: 1) the set of taxa is different using ITS1- and ITS2-based identification; 2) analysis of the ITS1 region reveals a greater number of operational taxonomic units; 3) ITS2 allows identification of AMF at the species level more often. Sample preparation for Illumina MiSeq analysis was optimized. Obligatory stages in the sample preparation were the purification of DNA in the agarose gel in Silica after isolation, as well as separate amplification of ITS1 and ITS2 followed by combining and joint sequencing for each sample. The results showed the highest AMF biodiversity for the 176Te sample from the ecosystem of the subalpine meadow of the southeastern slope of Malaya Hatipara mountain (43°25′48.0″N 41°42′31.0″E; 2401 m above sea level), in which 8 species of AMF were identified (Archaeospora spainiae, Claroideoglomus claroideum, Diversispora versiformis, Entrophpora infrequens, Funneliformis mosseae, Glomus indicum, Paraglomus laccatum, Rhizophagus irregularis).

The main methodological research results of the thermal conductivity of uranium dioxide (UO2) were considered. UO2 is the main fuel of modern nuclear energetic reactors. The assessment of efficiency of the proposed approximations compared to Fink-Ronchi formula at the theoretical values of UO2 density is proposed. According to this methodology we conducted the analysis of the experimental dependences of the thermal conductivity obtained by domestic authors.