TAXONOMY OF CORYNEBACTERIUM-DIPHTHERIAE AND RELATED TAXA, WITH RECOGNITION OF CORYNEBACTERIUM ULCERANS SP-NOV NOM REV

Levels of genomic DNA relatedness were determined using a S1 nuclease procedure for reference bacteria identified as biotypes of Corynebacte rium diphtheriae, biovars of Corynebacterium pseudotuberculosis, and ' Corynebacterium ulcerans'. These results showed that the three species are separate taxa at the genomospecies level whereas biotypes and bio vars are closely related genomically within each species. Phylogenetic analyses of small-subunit rDNA sequences revealed that 'Colynebacteri um ulcerans' forms a tight cluster with Corynebacterium pseudotubercul osis within the robust branch that groups all Corynebacterium sequence d to date. Therefore, we propose that the species incertae sedis 'C. u lcerans' should be conclusively recognized as a distinct species withi n the genus Corynebacterium with strain CCUG 2708 = NCTC 7910 as type strain. This species is characterized by urease production and ferment ation of glycogen.