Editing Pilus (section)

=== Fimbriae ===
[[Image:E. coli fimbriae.png|thumb|''[[Escherichia coli]]''.]]
'''Fimbria''' ([[Latin]] for 'fringe', {{plural form}}: '''fimbriae''') is a term used for a short pilus, an [[Appendage#Types in prokaryotes|appendage]] that is used to attach the bacterium to a surface, sometimes also called an "attachment pilus"<ref>{{cite journal |last1=Proft |first1=T. |last2=Baker |first2=E. N. |title=Pili in Gram-negative and Gram-positive bacteria — structure, assembly and their role in disease |journal=Cellular and Molecular Life Sciences |date=February 2009 |volume=66 |issue=4 |pages=613–635 |doi=10.1007/s00018-008-8477-4|pmid=18953686 |s2cid=860681 |doi-access=free |pmc=11131518 }}</ref> or '''adhesive pilus'''. The term "fimbria" can refer to many different (structural) types of pilus. Indeed, many different types of pili have been used for adhesion, a case of [[convergent evolution]].<ref name="pmid24133488">{{cite journal |last1=Chagnot |first1=C |last2=Zorgani |first2=MA |last3=Astruc |first3=T |last4=Desvaux |first4=M |title=Proteinaceous determinants of surface colonization in bacteria: bacterial adhesion and biofilm formation from a protein secretion perspective. |doi-access=free |journal=Frontiers in Microbiology |date=14 October 2013 |volume=4 |pages=303 |doi=10.3389/fmicb.2013.00303 |pmid=24133488|pmc=3796261 }}</ref> The [[Gene Ontology]] system does not treat fimbriae as a distinct type of appendage, using the generic pilus (GO:0009289) type instead.

This appendage ranges from 3–10 nanometers in diameter and can be as much as 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.

Fimbriae possess [[bacterial adhesin|adhesins]] which attach them to some sort of substratum so that the bacteria can withstand [[shear force]]s and obtain nutrients.  For example, ''[[E. coli]]'' uses them to attach to [[Mannose receptor|mannose receptors]]. 

Some [[aerobic organism|aerobic bacteria]] form a very thin layer at the surface of a [[growth medium#Types|broth culture]]. This layer, called a [[wiktionary:pellicle|pellicle]], consists of many aerobic bacteria that adhere to the surface by their fimbriae. Thus, fimbriae allow the aerobic bacteria to remain both on the broth, from which they take nutrients, and near the air.

Fimbriae are required for the formation of [[biofilm]], as they attach bacteria to host surfaces for colonization during infection. Fimbriae are either located at the poles of a cell or are evenly spread over its entire surface.

This term was also used in a lax sense to refer to all pili, by those who use "pilus" to specifically refer to sex pili.<ref>{{cite journal |last1=Ottow |first1=JC |title=Ecology, physiology, and genetics of fimbriae and pili. |journal=Annual Review of Microbiology |date=1975 |volume=29 |pages=79–108 |doi=10.1146/annurev.mi.29.100175.000455 |pmid=1180526}}</ref>