The organ of adhesion in the bacteria is -

Fimbriae is a very fine, hair-like surfaces appendages called fimbriae or pili. 8 morphological types are known classifiable as either common or sex pili on the basis of their function. Pili comprise self aggregating monomers of pilin. They originate in the cell membrane. Fimbriae can be seen only under the electron microscope. They are unrelated to motility. Fimbriae function as organs of adhesion helping the cells to adhere firmly to the paicle of various kinds. This propey may serve to anchor the bacteria in nutritionally orable microenvironments. Fimbriated bacteria form surface pellicles in liquid media. Many fimbriated cells agglutinate red blood cells of guinea pigs, fowl, horses, and pigs strongly human and sheep cells weakly and ox cells scarcely. A special type of fimbriae is sex pili . They are found on male bacteria and help in the attachment of those cells to female bacteria forming hollow conjugation tubes through which it is assumed genetic material is transferred from the donor to the recipient cell. Ref: Ananthanarayan & paniker's Textbook of Microbiology 9th edition pg no 20