Sabri M. Naser,  Marc Vancanneyt, Bart Hoste, Cindy Snauwaert, Katrien Vandemeulebroecke & Jean Swings

The taxonomic relatedness between the species Enterococcus casseliflavus and Enterococcus flavescens, and between Enterococcus italicus and Enterococcus saccharominimus was investigated. Literature data already indicated the synonymy between E. casseliflavus and E. flavescens, but this observation has never been formally published.  Additional evidences that both taxa represent a single species were provided by comparison of the partial sequences for three housekeeping genes, phenylalanyl-tRNA synthase alpha subunit (pheS), RNA polymerase alpha subunit (rpoA) and the alpha subunit of ATP synthase (atpA). Further genomic data derived from DNA-DNA hybridization had demonstrated that both species are synonymous. For E. italicus and E. saccharominimus, two recently described taxa, a high 16S rRNA gene sequence similarity of > 99% and analogous phenotypic features indicate a close taxonomic relatedness. The same multilocus sequence analysis (MLSA) scheme for the three housekeeping genes was also applied on E. italicus and E. saccharominimus and indicated possible conspecificity, an observation that was also confirmed by a high DNA–DNA binding value (≥ 78%). Data from the present study led to the proposal that E. flavescens should be reclassified as E. casseliflavus, and that E. saccharominimus should be reclassified as E. italicus.