Sequencing the gene encoding manganese-dependent superoxide dismutase for rapid species identification of enterococci

Simple PCR and sequencing assays that utilize a single pair of degenerate p rimers were used to characterize a 438-bp-long DNA fragment internal (sodA( int)) to the sodA gene encoding the manganese-dependent superoxide dismutas e in 19 enterococcal type strains (Enterococcus avium, Enterococcus casseli flavus, Enterococcus cecorum, Enterococcus columbae, Enterococcus dispar, E nterococcus durans, Enterococcus faecalis, Enterococcus faecium, Enterococc us flavescens, Entrococcus gallinarum, Enterococcus hirae, Enterococcus mal odoratus, Enterococcus mundtii, Enterococcus pseudoavium, Enterococcus raff inosus, Enterococcus saccharolyticus, Enterococcus seriolicida, Enterococcu s solitarius, and Enterococcus sulfureus). Sequence analysis of the sodA(in t) fragments enabled reliable identification of 18 enterococcal species, in cluding E. casseliflavus-E. flavescens and E. gallinarum, The sodA, fragmen ts of E. casseliflavus and E. flavescens were almost identical (99.5% seque nce identity), which suggests that they should be associated in a single sp ecies. Our results confirm that the sodA gene constitutes a more discrimina tive target sequence than 16S rRNA gene in differentiating closely related bacterial species.