Transfer of Propionibacterium innocuum Pitcher and Collins 1991 to Propioniferax gen. nov. as Propioniferax innocua comb. nov.

16S ribosomal DNA analysis indicates that Propionibacterium innocuum is a phylogenetic neighbor of Luteococcus japonicus and that this pair of organisms branches intermediately between the genus Propionibacterium on the one side and the genera Aeromicrobium and Nocardioides on the other side. Phenotypically, strains of P. innocuum differ from species of Propionibacterium by exhibiting aerobic growth and possessing arabinose in the cell wall, they differ from species of Aeromicrobium and Nocardioides by the formation of propionic acid, and they differ from species of Luteococcus in morphology. Consequently, P. innocuum should not be classified with authentic Propionibacterium species, and the transfer of P. innocuum Pitcher and Collins 1991 to a new genus, Propioniferax, as Propioniferax innocua gen. nov., comb. nov. is proposed.