Taxonomic status of Corynebacterium diphtheriae biovar Belfanti and proposal of Corynebacterium belfantii sp. nov.

Clinical isolates belonging to Corynebacterium diphtheriae biovar Belfanti were characterized by genomic sequencing and biochemical and chemotaxonomic analyses. Phylogenetic analyses indicated that biovar Belfanti represents a branch that is clearly demarcated from C. diphtheriae strains of biovars Mitis and Gravis. The average nucleotide identity of isolates of biovar Belfanti with C. diphtheriae type strain NCTC 11397T (biovar Gravis) was 94.85 %. The inability to reduce nitrate differentiated biovar Belfanti from other strains of C. diphtheriae. On the basis of these results, we propose the name Corynebacterium belfantii sp. nov. for the group of strains previously considered as C. diphtheriaebiovar Belfanti. The type strain of C. belfantii is FRC0043T (=CIP 111412T=DSM 105776T). Strains of C. belfantii were isolated mostly from human respiratory samples.