F. nucleatum ssp. nucleatum actively sialylates its outer surface.

A) F. nucleatum ssp. nucleatum was grown in SDM before fluorescently labeling surface sialic acids. B) F. nucleatum ssp. nucleatum was grown in the presence of SDM and pretreated with neuraminidase before fluorescently labeling surface sialic acids. All pictures in the left panels are phase contrast images, whereas the right panel images are the corresponding images captured using epifluorescence microscopy. Total magnification is 1000x.