Proposal of Enterococcus xinjiangensis Ren et al. 2020 as a later heterotypic synonym of Enterococcus lactis Morandi et al. 2012.

Enterococcus lactis was published in the International Journal of Systematic and Evolutionary Microbiology in June 2012. Enterococcus xinjiangensis was published in Current Microbiology in 2016 and validated in November 2020. In the present study, the relationship between E. lactis and E. xinjiangensis was re-evaluated. In the 16S rRNA gene phylogeny, E. xinjiangensis was closely related to E. lactis and Enterococcus faecium. The type strains of E. xinjiangensis and E. lactis shared 99.8 % 16S rRNA gene sequence similarity, 98.5 % pheS sequence similarity, 99.9 % rpoA sequence similarity, 98.7 % average nucleotide identity (ANI) value and 88.9 % digital DNA-DNA hybridization (dDDH) value, indicating that they represent the same species. Meanwhile, although the type strains of E. xinjiangensis and E. faecium also shared 99.8 % 16S rRNA gene sequence similarity, 97.1 % pheS sequence similarity and 99.6 % rpoA sequence similarity, 94.7 % ANI and 59.1 % dDDH values indicated that they represent two different species. On the basis of the results present here, we propose Enterococcus xinjiangensis Ren et al. 2020 as a later heterotypic synonym of Enterococcus lactis Morandi et al. 2012.