A numerical taxonomic and serological study of Listeria and possibly related bacteria.

A numerical taxonomic survey has heen performed using 192 strains of Listeria and possibly related bacteria. Of these, 38 strains have heen further investigated hy serological techniques. The results indicate that Listeria monocytogenes is a good, homogeneous species, L. grayi and L, murrayi do not differ sufficiently from each other to warrant individual specific status, and it is recommended that they he combined in the single species L, grayi. They show a close relationship to L. monocytogenes, compatible with that of two species within the same genus, but L. denitrificans differs greatly from the other Listeria spp, and should be removed from the genus, Erysipelothrix, Listeria and Microbacterium thermosphac- tum show a closer resemblance to the family Lactobacillaceae than to the family Corynebacteriaceae where they are at present classified. The suggested relationship of Gemella haemol- ysans to the tribe Streptococceae in the Lactobacillaceae has been confirmed, and it is possible to envisage an enlarged family Lactobacillaceae including Listeria, Erysipelothrix, M. thermosphactum, G. haemolysans and possibly the bacteria refered to as Bacterium eurydice. Alternatively, Erysipeloth- rix, M. thermosphactum, G, haemolysans and possibly B. eurydice could be placed in the Lactobacillaceae, and a new family, possibly the Listeriaceae could be introduced for Listeria and the many lactic acid bacteria which appear to be related to Listeria, but have not been assigned to an exact taxonomic position.