Diversity of human small intestinal S treptococcus and V eillonella populations

Molecular and cultivation approaches were employed to study the phylogenetic richness and temporal dynamics of S treptococcus and V eillonella populations in the small intestine. Microbial profiling of human small intestinal samples collected from four ileostomy subjects at four time points displayed abundant populations of S treptococcus spp. most affiliated with S . salivarius, S . thermophilus, and S . parasanguinis , as well as V eillonella spp. affiliated with V . atypica , V . parvula , V . dispar , and V . rogosae . Relative abundances varied per subject and time of sampling. S treptococcus and V eillonella isolates were cultured using selective media from ileostoma effluent samples collected at two time points from a single subject. The richness of the S treptococcus and V eillonella isolates was assessed at species and strain level by 16S r RNA gene sequencing and genetic fingerprinting, respectively. A total of 160 S treptococcus and 37 V eillonella isolates were obtained. Genetic fingerprinting differentiated seven S treptococcus lineages from ileostoma effluent, illustrating the strain richness within this ecosystem. The V eillonella isolates were represented by a single phylotype. Our study demonstrated that the small intestinal S treptococcus populations displayed considerable changes over time at the genetic lineage level because only representative strains of a single S treptococcus lineage could be cultivated from ileostoma effluent at both time points.