Ecological implications of glucosyltransferase phase variation in Streptococcus gordonii

When sucrose is provided as a substrate for glucosyltransferase (GTF), Spp+ cells of the oral bacteria Streptococcus gordonii grow embedded in an insoluble glucan mass associated with surfaces. Spp- phase variants with lower GTF activity, which either arise from or are grown with Spp+ cells, segregate preferentially as unattached cells in the culture supernatants. Conversely, Spp+ revertants preferentially accumulate on surfaces. GTF phase variation, therefore, may facilitate the dispersion of S. gordonii cells throughout the oral cavity.