Enterococcus lactis sp. nov., from Italian raw milk cheeses

The taxonomic positions of ten atypical Enterococcus strains isolated from raw milk Italian cheeses were investigated in a polyphasic study. 16S rRNA, phenylalanyl-tRNA synthase alpha subunit (pheS) and RNA polymerase alpha subunit (rpoA) gene sequence analysis, intergenic transcribed spacer analysis and randomly amplified polymorphic DNA (RAPD) PCR, and an examination of phenotypic properties revealed the novel isolates to be a novel enterococcal species. On the basis of the 16S rRNA analysis, the strains were found to be closely related to Enterococcus hirae, Enterococcus durans and Enterococcus faecium with 98.8, 98.9 and 99.4 % sequence similarity. The reference strain BT159T occupied a separate position on the basis of sequence analysis of the housekeeping gene pheS relative to the type strain of E. faecium. This group of strains can be easily differentiated from other Enterococcus species by RAPD-PCR, 16S–23S rRNA gene intergenic transcribed spacer analysis and phenotypic characteristics. The name Enterococcus lactis sp. nov. is proposed for this species, with strain BT159T (=DSM 23655 =LMG 25958) as the type strain.