JUSTIFICATION OF THE CLASSICAL PROPIONIBACTERIUM SPECIES CONCEPT BY RESTRICTION ANALYSIS OF THE 16S RIBOSOMAL-RNA GENES

The genus Propionibacterium consists of two principal groups, the ''cl assical'' and the ''cutaneous'' strains. The identification of the ''c lassical'' species and unidentified strains of these commercially impo rtant bacteria is however, still problematic. Certain regions of the 1 6S ribosomal RNA gene of the ''classical'' Propionibacterium were ampl ified by polymerase chain reaction, and the polymorphic restriction si tes within these amplified regions were used to distinguish between th e various species. Visual differentiation between the various ''classi cal'' Propionibacterium species was possible after restriction endonuc lease digestion of the PCR products, using HaeIII, AluI and HpaII. Wit h the exception of strains originally received labelled as ''P. rubrum '' and ''P. sanguineum'', the results confirm the consolidation of the various ''classical'' groups to form the current classification syste m. A higher degree of similarity was found between both the ''P. rubru m'' and ''P. sanguineum'' strains and the P. jensenii type strain, tha n between these two strains and P. thoenii, wherein these strains are currently consolidated. The protocol described is recommended as a rap id and sensitive technique for the identification of the ''classical'' Propionibacterium.