This article has reviewed the formation and composition of milk protein pellicles, including casein, whey protein, minerals and proteose-peptones.Th...
Because they're on the pellicle of the teeth, these bacteria come into contact with sucrose, a sugar found in various foods and drinks including table sugar.
Normally, there's a layer called the pellicle that covers the tooth, and bacteria in the mouth, like viridans group streptococci, settle on that pellicle layer.