Differences between pili and fimbriae

S.N                     Pili S.N                     Fimbriae
1. These are fine hair-like microfibers. 1. These are tiny bristle-like fibers.
2. These are longer than fimbriae. 2. These are shorter than fimbriae.
3. These are less in number. 3. These are more in number.
4. About one to ten pili are present in every cell. 4. About 200-400 fimbriae are present in each cell.
5. Only present in gram negative bacteria. 5. Both gram negative and gram-positive bacteria contain it.
6. These are made up of pilin protein. 6. These are made up of fimbrillin protein.
7. These are rigid in structure as compared to fimbriae. 7. These are less rigid than pili.
8. Plasmid genes govern the formation of pili. 8. Bacterial genes in the nucleoid are responsible for formation of fimbriae.
9. Helps in bacterial conjugation. 9. Helps in attachment or adherence to the surface of other bacteria.
10. These are thicker in structure. 10. These are thinner than pili.
11. Related to twitching motility especially type IV pili. 11. No association with motility.
12. Acts as receptors for some viruses. 12. No activity related to receptors.
13. Length ranges from 0.5-2 µm. 13. Length ranges from 0.03-0.14 µm.
14. Distribution is random on the surface of the cell. 14. Distribution is uniform or even throughout the cell.


15. These are hollow tubular in structure. 15. These are solid in structure.
16. Bacteria like E.coli, N. gonorrhoeae, Pseudomonas, etc. contain pili. 16. Fimbriae having bacteria are Salmonella typhimurium, Shigella dysenteriae, etc.


What is the function of fimbriae? Where is it found? - Quora        Cellular appendages (Fimbria or Pili) | Biology Ease

Image source:  quora                           Image source:  biologyease     


i) https://microbiologynotes.com/differences-between-fimbriae-and-pili/

ii) https://www.easybiologyclass.com/difference-between-pili-and-fimbriae-of-bacteria-a-comparison-table/

Differences between pili and fimbriae