A numerical taxonomic survey of Listeria and related bacteria

A numerical taxonomic study was performed on named strains of Listeria, Erysipelothrix, Microbacterium thermosphactum, Lactobacillus, Streptococus, Propionibacterium, Kurthia and some possibly related bacteria using I43 unit characters covering a wide range of properties. The strains fell into six main clusters: (A) Listeria; (B) Microbacterium thermosphactum, Lactobacillus, Streptococcus; (C) Gemella, Erysipelothrix; (D) Kurthia and mainly aerobic corynebacteria; (E) Propionibacterium, Staphylococcus; (F) mainly Cellulomonas. The genus Listeria contained three subgroups corresponding to (I) Listeria monocytogenes, (2) Listeria grayi and (3) non-haemolytic listeria strains. Listeria murrayi did not appear to be sufficiently distinct from Listeria grayi to warrant separate species status. The genus Erysipelothrix was quite separate from the genus Listeria. Microbacterium thermosphactum was related to both the genera Listeria and Lactobacillus but formed a separate phenon that could appropriately be given generic rank. There were four distinct subgroups amongst the streptococci examined. Gemella strains appeared as a distinct phenon related to Erysipelothrix and the streptococci. The lactobacilli grouped into four phena largely corresponding to the subgenera Betabacterium, Streptobacterium and Thermobacterium and to the species Lactobacillus mali. Custers A, B, and C displayed a relatively close association to each other and it is recommended that all be included in the family Lactobacillaceae.