<P> In bacteriology, a fimbria (plural fimbriae), also referred to as an "attachment pilus" by some scientists, is an appendage that can be found on many Gram - negative and some Gram - positive bacteria that is thinner and shorter than a flagellum . This appendage ranges from 3 - 10 nanometers in diameter and can be up to several micrometers long . Fimbriae are used by bacteria to adhere to one another and to adhere to animal cells and some inanimate objects . A bacterium can have as many as 1,000 fimbriae . Fimbriae are only visible with the use of an electron microscope . They may be straight or flexible . </P> <P> Fimbriae carry adhesins which attach them to the substratum so that the bacteria can withstand shear forces and obtain nutrients . For example, E. coli uses them to attach to mannose receptors . </P> <P> Some aerobic bacteria form a very thin layer at the surface of a broth culture . This layer, called a pellicle, consists of many aerobic bacteria that adhere to the surface by their fimbriae . Thus, fimbriae allow the aerobic bacteria to remain on the broth, from which they take nutrients, while they congregate near the air . </P> <P> "Gram - negative bacteria assemble functional amyloid surface fibers called curli ." Curli are a type of fimbriae; another type are called type I fimbriae . Curli are composed of proteins called curlins . Some of the genes involved are CsgA, CsgB, CsgC, CsgD, CsgE, CsgF, and CsgG . </P>

What is the function of the fimbriae seen surrounding this e. coli cell