Adhesin, Bacterial

Cell-surface components or appendages of Bacteria that facilitate adhesion (Bacterial Adhesion) to other Cells or to inanimate surfaces. Most fimbriae (Fimbriae, Bacterial) of Gram-Negative Bacteria function as adhesins, but in many cases it is a Minor subunit protein at the tip of the fimbriae that is the actual adhesin. In Gram-Positive Bacteria, a protein or polysaccharide surface layer serves as the specific adhesin. What is sometimes called polymeric adhesin (Biofilms) is distinct from protein adhesin.