Streptococcus lactarius sp. nov., isolated from breast milk of healthy women.

Three strains of a hitherto-unknown, Gram-stain-positive coccus were recovered from the milk of three non-related healthy women. The isolates shared 99% 16S rRNA gene sequence similarity with sequences from uncultured members of the Lactobacillales and Streptococcus. The closest sequence corresponding to a defined species was that of Streptococcus peroris GTC 848T, with a similarity of 98%. A partial sequence (488 bp) of the tuf gene also showed 97% similarity with that of S. peroris CCUG 39814T. The combined 16S rRNA/tuf-based phylogeny revealed that all the isolates grouped in a statistically well-supported cluster separate from S. peroris. Enzyme activity profiles as well as fermentation…