[Propionic acid cocci and their taxonomic position]

In order to determine the taxonomic position of propionic cocci, the authors studied their morphological, cultural and biochemical properties, the fatty acid composition of cells, and established the degree of homology for the DNAs of cocci and classical propionic bacteria using the method of molecular hybridization. The cocci were found to have the activities of catalase and superoxide dismutase which were higher than in the studied propionic bacteria. The propionic cocci and propionic bacteria were shown to be similar in terms of their fatty acid composition and to contain the C15-saturated acid in the form of anteiso isomer as the main type of fatty acids. Their fatty acid composition was most similar to that of the species Propionibacterium jensenii (P. technicum). The propionic cocci and bacteria are related in the structure of their genomes, particularly, in the case of the bacterium P. jensenii (P. raffinosaceum)--49%. On the basis of studying the phenotypic characteristics, the fatty acid composition, the nucleotide composition of DNA, and the high degree of homology between the DNAs of the cocci and the bacterial species P. jensenii (P. raffinosaceum), the authors propose to assign the cocci to the genus Propionibacterium as a new species Propionibacterium coccoides.