Differentiation of the genus Listeria from other gram-positive species based on low molecular weight (LMW) RNA profiles.

Low molecular weight RNA (LMW RNA; 5S rRNA and tRNAs) profiles of several Gram-positive species were generated on 9% denaturing polyacrylamide gels. The profiles of five Listeria spp. (L. innocua, L. ivanovii, L. monocytogenes, L. seeligeri and L. welshimeri) were identical when cultured in three different media (APT, BHI and TSBYE), either shaken or statically, both at 30 and 37 degrees C. Twenty-six strains from 15 other species representing seven different genera were also compared. Each species exhibited a characteristic profile. Strain variants of the same species gave identical profiles. The technique represents a simple, reproducible approach to the identification of species and possibly of relationships between species. The taxonomic and phylogenetic implications, particularly with respect to Listeria spp., Brochothrix thermosphacta and the lactic acid bacteria, are considered.