The paper presents the result of the research of the the typical chernozem microbiome of. The aim of the work was to identify the key taxa of the most abundant phylum - Proteobacteria. Characterization of the compositional diversity of the soil microbiome from the “Biotron” Experimental Station of the Academy of Sciences of Moldova was achieved by the 16S rRNA amplicon sequencing (Scientific Center “Genomic Technologies, Proteomics and Cell Biology” of FSBSI ARRIAM, St. Petersburg, Russia). For the interpretation of the results, a bibliographic study was carried out. It was found that the dominant genera of Proteobacteria were Sphingomonas, Microvirga, Skermanella. Among these, the genus Sphingomonas had the highest relative abundance: 1.23-6.58% in cultivated agricultural soil and can be considered a keystone taxa. Deeper knowledge of the ecological distribution and diversity of Sphingomonas bacteria in soil may provide new insights to explore its agricultural potential in promoting plant growth, remediating polluted soils, mitigating abiotic stress.