Six aerobic gram-positive nonspore-forming bacterial strains belonging to the Kurthia genus were isolated from the Magadan (Susuman) mammoth found in the permafrost of the East Siberia. The strains are a phenotypically homogeneous group different from the two known species (K. zopfii and K. gibsonii) in requiring more vitamins, the absence of growth in a medium with 7% NaCl, and a low level of DNA-DNA hybridization (not more than 45%). Moreover, the strains differ from K. zopfii in the synthesis of a yellow pigment, the activity of phosphatase, and the absence of coccoid forms; the bacteria differ from K. gibsonii in the absence of growth at a temperature above 40 degrees C. The organisms are referred to as Kurthia sibirica sp. nov. The type strain 13-2 has been deposited in the All-Union Collection of Microorganisms as strain VKB B-1549.