“…In exposed surfaces such as tongue, mucosa and supragingival surfaces of teeth, dietary products as well as saliva components are the main available nutritional sources, while in the subgingival crevice the resident microorganisms obtain nutrients mainly from GCF. Saliva contains glycoproteins such as mucins, amylase, and immunoglobulin (Ig) A (52, 59), while GCF contains many serum-derived proteins, such as hemoglobin-derived peptides, IgM, IgG and albumin, which serve as nutrients for sub-gingival species (50, 60, 61, 62). Bacteria from supragingival plaque use host glycoproteins as a major energy source and function as a microbial community to sequentially degrade these structurally complex molecules (39, 63).…”