Biochemical and genetic evidence for the transfer of Enterococcus solitarius Collins et al 1989 to the genus Tetragenococcus as Tetragenococcus solitarius comb. nov.

Phylogenetic analysis of 16S rRNA gene sequences revealed that Enterococcus solitarius is not a member of the genus Enterococcus, but is related to species of the genus Tetragenococcus. On a phylogenetic tree, E solitarius clustered with Tetragenococcus halophilus and Tetragenococcus muriaticus, with which it showed the highest 16S rRNA gene sequence similarity level (about 94 %). Phenotypic studies indicated that E solitarius was also unable to produce acid from lactose, providing further evidence of its affiliation to the genus Tetragenococcus. DNA hybridization studies indicated that E solitarius was clearly a separate species, different from T halophilus and T muriaticus (reassociation levels of about 23 and 54 %, respectively). As suggested in previous studies, E solitarius is closely related to but clearly distinct from T halophilus. Based upon properties that taxonomically distinguish it from species of the genus Enterococcus, it is proposed that E solitarius be transferred to the genus Tetragenococcus and reclassified as Tetragenococcus solitarius comb. nov. (type strain, 885/78(T) =ATCC 49428(T) =CCUG 29293(T)=CIp 103330(T) =DSM 5634(T) =JCM 8736(T) = LMG 12890(T) =NCTC 12193(T)).