Editing Biofilm (section)

=== Formation of biofilms ===

The formation of a biofilm begins with the attachment of free-floating microorganisms to a surface.<ref name="O'Toole_1998" /><ref name="Watnick_2000" /> The first colonist bacteria of a biofilm may adhere to the surface initially by the weak [[van der Waals force]]s and hydrophobic effects.<ref name="pmid11397632">{{cite journal | vauthors=Briandet R, Herry J, Bellon-Fontaine M | title=Determination of the van der Waals, electron donor and electron acceptor surface tension components of static Gram-positive microbial biofilms | journal=Colloids Surf B | volume=21 | issue=4 | pages=299–310 | date=August 2001 | pmid=11397632 | doi=10.1016/S0927-7765(00)00213-7 }}</ref><ref name="pmid20438621">{{cite journal | vauthors=Takahashi H, Suda T, Tanaka Y, Kimura B | title=Cellular hydrophobicity of Listeria monocytogenes involves initial attachment and biofilm formation on the surface of polyvinyl chloride | journal=Lett. Appl. Microbiol. | volume=50 | issue=6 | pages=618–25 | date=June 2010 | pmid=20438621 | doi=10.1111/j.1472-765X.2010.02842.x | s2cid=24880220 | doi-access=free }}</ref> If the colonists are not immediately separated from the surface, they can anchor themselves more permanently using [[cell adhesion]] structures such as [[pilus|pili]]. A unique group of Archaea that inhabit [[anoxic waters|anoxic groundwater]] have similar structures called [[Hamus (archaea)|hami]]. Each hamus is a long tube with three hook attachments that are used to attach to each other or to a surface, enabling a community to develop.<ref name="archaea">{{cite web |title=7: Archaea |url=https://bio.libretexts.org/Bookshelves/Microbiology/Book%3A_Microbiology_(Bruslind)/07%3A_Archaea |website=Biology LibreTexts |language=en |date=6 February 2018 |access-date=10 August 2020 |archive-date=23 September 2020 |archive-url=https://web.archive.org/web/20200923100806/https://bio.libretexts.org/Bookshelves/Microbiology/Book%3A_Microbiology_(Bruslind)/07%3A_Archaea |url-status=live }}</ref><ref name="Brock">{{cite book | vauthors=Madigan M |title=Brock biology of microorganisms |date=2019 |publisher=Pearson |isbn=978-1-292-23510-3 |page=86 |edition=Fifteenth, Global}}</ref> Hyperthermophilic archaeon ''[[Pyrobaculum]] calidifontis'' produce bundling pili which are homologous to the bacterial TasA filaments, a major component of the extracellular matrix in bacterial biofilms, which contribute to biofilm stability.<ref name=Wang2022PNAS>{{cite journal | vauthors=Wang F, Cvirkaite-Krupovic V, Krupovic M, Egelman EH | title=Archaeal bundling pili of ''Pyrobaculum calidifontis'' reveal similarities between archaeal and bacterial biofilms | journal=Proceedings of the National Academy of Sciences of the United States of America | volume=119 | issue=26 | pages=e2207037119 | date=June 2022 | pmid=35727984 | pmc=9245690 | doi=10.1073/pnas.2207037119 | doi-access=free | bibcode=2022PNAS..11907037W }}</ref> TasA homologs are encoded by many other archaea, suggesting mechanistic similarities and evolutionary connection between bacterial and archaeal biofilms.<ref name=Wang2022PNAS />

[[File:A114, Lava Beds National Monument, California, USA, Golden Dome Lava Tube Cave, 2004.jpg|thumb|Biofilm of golden [[hydrophobic]] [[bacteria]]; ceiling of Golden Dome Cave, a [[lava tube]] in [[Lava Beds National Monument]]<ref>[https://www.nps.gov/places/golden-dome-cave.htm "Golden Dome Cave"] {{Webarchive|url=https://web.archive.org/web/20221213013714/https://www.nps.gov/places/golden-dome-cave.htm |date=13 December 2022 }}. National Park Service. November 6, 2021. Retrieved February 11, 2024.</ref>]]

[[Hydrophobicity]] can also affect the ability of bacteria to form biofilms. Bacteria with increased hydrophobicity have reduced repulsion between the substratum and the bacterium.<ref name="Donlan2002">{{cite journal | vauthors=Donlan RM | year=2002 | title=Biofilms: Microbial Life on Surfaces | journal=Emerging Infectious Diseases | volume=8 | issue=9| pages=881–890 | doi=10.3201/eid0809.020063 | pmid=12194761 | pmc=2732559}}</ref> Some bacteria species are not able to attach to a surface on their own successfully due to their limited motility but are instead able to anchor themselves to the matrix or directly to other, earlier bacteria colonists. [[Non-motile bacteria]] cannot recognize surfaces or aggregate together as easily as motile bacteria.<ref name="Donlan2002" />

During surface colonization bacteria cells are able to communicate using [[quorum sensing]] (QS) products such as [[N-acyl homoserine lactone]] (AHL). Once colonization has begun, the biofilm grows by a combination of cell division and recruitment. [[Polysaccharide]] matrices typically enclose bacterial biofilms. The matrix exopolysaccharides can trap QS autoinducers within the biofilm to prevent predator detection and ensure bacterial survival.<ref>{{cite journal | vauthors=Li S, Liu SY, Chan SY, Chua SL | title=Biofilm matrix cloaks bacterial quorum sensing chemoattractants from predator detection | journal=The ISME Journal | pages=1388–1396 | date=January 2022 | volume=16 | issue=5 | pmid=35034106 | doi=10.1038/s41396-022-01190-2 | pmc=9038794 | bibcode=2022ISMEJ..16.1388L }}</ref> In addition to the polysaccharides, these matrices may also contain material from the surrounding environment, including but not limited to minerals, soil particles, and blood components, such as erythrocytes and fibrin.<ref name="Donlan2002" /> The final stage of biofilm formation is known as development, and is the stage in which the biofilm is established and may only change in shape and size.{{Citation needed|date=February 2024}}

The development of a biofilm may allow for an aggregate cell colony to be increasingly tolerant<ref>{{cite journal | vauthors=Ciofu O, Tolker-Nielsen T | title=Tolerance and Resistance of ''Pseudomonas aeruginosa'' Biofilms to Antimicrobial Agents-How ''P. aeruginosa'' Can Escape Antibiotics | journal=Frontiers in Microbiology | volume=10 | pages=913 | date=2019 | pmid=31130925 | pmc=6509751 | doi=10.3389/fmicb.2019.00913 | doi-access=free }}</ref> or [[antibiotic resistance|resistant to antibiotics]]. Cell-cell communication or [[quorum sensing]] has been shown to be involved in the formation of biofilm in several bacterial species.<ref name="Sakuragi">{{cite journal | vauthors=Sakuragi Y, Kolter R | title=Quorum-sensing regulation of the biofilm matrix genes (pel) of Pseudomonas aeruginosa | journal=Journal of Bacteriology | volume=189 | issue=14 | pages=5383–6 | date=July 2007 | pmid=17496081 | pmc=1951888 | doi=10.1128/JB.00137-07 | doi-access=free }}</ref>