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Updated: Jun 12, 2026

Isolation of Leukocytes from Human Breast Milk for Use in an Antibody-dependent Cellular Phagocytosis Assay of HIV Targets
Published on: September 6, 2019
Streptococcus lactarius sp. nov., isolated from breast milk of healthy women
Virginia Martín1, Rosario Mañes-Lázaro2, Juan Miguel Rodríguez1
1Departamento de Nutrición, Bromatología y Tecnología de los Alimentos, Universidad Complutense de Madrid, 28040 Madrid, Spain.
Abstract:
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 848(T), with a similarity of 98 %. A partial sequence (488 bp) of the tuf gene also showed 97 % similarity with that of S. peroris CCUG 39814(T). 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 patterns differentiated the novel bacteria from other members of the Streptococcus mitis group. Finally, phenotypic, genotypic and phylogenetic data supported the proposal of a novel species of the genus Streptococcus, for which the name Streptococcus lactarius sp. nov. is proposed. The type strain is MV1(T) ( = CECT 7613(T) = DSM 23027(T)).
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