The researchers (we) investigated how infant oral bacterial communities develop during their first six months of life, with the aim to understand which microbes colonize, how they establish themselves and why they succeed together. Using high throughput DNA sequencing techniques, we analyzed oral samples from 24 mother-infant pairs at one and six months after birth. We found two abundant, but previously unknown bacterial species (one Streptococcus spp. and one Rothia spp.) at six months of age. These bacteria consistently appear together across different babies, suggesting they may depend on each other for survival and growth. By reconstructing the genomes of these bacteria directly from our samples, we discovered specific genetic features that help explain their success in the infant mouth. Streptococcus carries genes involved in amino acid biosynthesis (including arginine biosynthesis using amino acids present in breast milk) as well as enzymes that help break down carbohydrates in the oral biofilm. Rothia has genes associated with cell membrane biosynthesis and carbohydrate metabolism, while producing nutrients that Streptococcus needs. We predict these bacteria exchange key nutrients like ornithine and lysine, creating a mutually beneficial partnership.
Overall, our findings offer a first look at the functional roles and potential interactions of these overlooked species, laying the groundwork for future experimental work to validate these predictions.
https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1013185
