Differences in the profiles of salivary proteins bound to S. gordonii and S. aureus. Bacteria were exposed to salivary secretions and washed to remove unbound proteins. Bound proteins were eluted from the bacterial organisms and separated by SDS-PAGE. Protein and glycoprotein bands were revealed by a combination of Coomassie blue and periodic acid-Schiff staining. The salivary eluate from S. gordonii strain CH1 after exposure to whole saliva shows salivary amylase as the predominant component being bound. The salivary eluate from S. aureus strain 8325 shows several bands (ranging from high to low molecular weight: DMBT-1gp-340, mucin-7, secretory component, immunoglobulin (Ig) α-chain, Ig γ-chain, Ig κ- and λ-chains, lysozyme, and protein S100-A9; Note: In contrast to S. gordonii, S. aureus does not bind salivary amylase.) (116). Eluates from several clinical isolates of S. aureus [isolated strains 7, 15, 41, 59, 74 (19)] after exposure to saliva show a similar pattern as for the type strain 8325. For comparison, the range of protein bands present in whole saliva are shown (left lane). This figure is a modified version of a figure published (116).