Organ of adhesion of bacteria is -
Fimbriae 

Some gram negative bacilli carry hair like projections called fimbriae or pilli.
Pilli are composed of antigenic pilin.
They are unrelated to motility and are found on motile as well as nonmotile bacteria.
Fimbriae function as organs of adhesion, helping the cells to adhere firmly to particles of various kind.


A special type of fimbriae is sex pills. These are found on 'male' bacteria and help in conjugation by forming conjugation tube through which genetic material is transferred from the donor to the recipient cell.
Capsule
Slime
Flagella
Fimbriae