Recent insights have been brought to the taxonomy of the genus Enterococcus by studies applying whole-cell protein analysis and DNA-DNA reassociation experiments, in addition to conventional physiological tests. Using these techniques, a group of 10 strains resembling the physiological group III of enterococcal species was characterized. Five strains were recovered from pigs and five from rats with enteric disorders. On the basis of the results of conventional physiological tests, the most likely identity of these strains was Enterococcus durans or Enterococcus hirae. Analysis of the electrophoretic whole-cell protein profiles showed two distinct clusters of virtually indistinguishable profiles: one composed of strains isolated from pigs, and one composed of strains isolated from rats. These protein profiles were not similar to the profiles of any previously described Enterococcus species. The results of DNA-DNA relatedness experiments were consistent with the results of the protein-profile analysis. The high levels of DNA relatedness found for pig isolates demonstrated that they belong to a new enterococcal species, for which the designation Enterococcus porcinus sp. nov. is proposed (type strain =DS 1390-83T =ATCC 700913T =CCUG 43229T =NCIMB 13634T). Strains isolated from rats were found to comprise another new species, for which the designation Enterococcus ratti sp. nov. is proposed (type strain =DS 2705-87T =ATCC 700914T =CCUG 43228T =NCIMB 13635T). This report provides data on the phenotypic and genotypic characterization of these two new enterococcal species, which may represent diarrhoeagenic pathogens for animals.

Strains from anal swabs and chronic otitis externa in dogs were shown to be phylogenetically related to the Enterococcus faecium species group. They shared a number of phenotypic characteristics with these species, but they could be easily differentiated by biochemical reactions. In addition, the canine strains were unusual in their nearly complete failure to grow on sodium azide-containing enterococci-selective media and in their Voges-Proskauer reactions (usually negative). By using 16S rRNA sequencing and DNA-DNA hybridization of representative strains, as well as tDNA interspacer gene PCR and SDS-PAGE of whole-cell proteins, the group of canine strains was shown to constitute a novel enterococcal species. The name Enterococcus canis sp. nov. is proposed for this species, with LMG 12316T (= CCUG 46666T) as the type strain. Concurrently, the taxonomic situation and nomenclatural position of Enterococcus porcinus were investigated. As no phenotypic or genotypic differences were found between this species and Enterococcus villorum, the name E. porcinus is considered to be a junior synonym of E. villorum.