The vaginal microbiome is a relatively simple, low-diversity ecosystem that plays a vital role in female health and is typically dominated by Lactobacillus species. Shotgun metagenomic sequencing enables detailed, strain-level analysis, offering deeper insights into microbial colonization and host-microbe interactions.
The study analyzed 354 vaginal metagenomes from pregnant women in Ireland to examine:
- Metagenomic community state types (CSTs)
- Strain-level variation, with a focus on cell surface interactions
Key findings:
- Lactobacillus crispatus and Lactobacillus iners were the most dominant species.
- Multiple subspecies were identified within dominant Lactobacillus strains.
- Subspecies of L. crispatus contained unique genes, including putative mucin-binding genes.
- 337 metagenome-assembled genomes (MAGs) showed:
- Higher numbers of strain-specific genes in L. crispatus
- Functional categories included cell wall biogenesis, carbohydrate metabolism, and amino acid metabolism
- Many of these genes were under positive selection
- A specific glycan-associated cell surface gene cluster was:
- Predominantly present in L. crispatus
- Absent in L. iners and Gardnerella vaginalis
