Editing Biofilm (section)

== Dispersal ==
Dispersal of cells from the biofilm colony is an essential stage of the biofilm life cycle. Dispersal enables biofilms to spread and colonize new surfaces. Enzymes that degrade the [[#Extracellular matrix|biofilm extracellular matrix]], such as [[dispersin B]] and [[deoxyribonuclease]], may contribute to biofilm dispersal.<ref>{{cite journal|vauthors=Kaplan JB, Ragunath C, Ramasubbu N, Fine DH |title=Detachment of Actinobacillus actinomycetemcomitans biofilm cells by an endogenous beta-hexosaminidase activity |journal=Journal of Bacteriology |volume=185 |issue=16 |pages=4693–8 |date=August 2003 |pmid=12896987 |pmc=166467 |doi=10.1128/JB.185.16.4693-4698.2003}}</ref><ref>{{cite journal|vauthors=Izano EA, Amarante MA, Kher WB, Kaplan JB |title=Differential roles of poly-N-acetylglucosamine surface polysaccharide and extracellular DNA in Staphylococcus aureus and Staphylococcus epidermidis biofilms |journal=Applied and Environmental Microbiology |volume=74 |issue=2 |pages=470–6 |date=January 2008 |pmid=18039822 |pmc=2223269 |doi=10.1128/AEM.02073-07|bibcode=2008ApEnM..74..470I }}</ref> Enzymes that degrade the biofilm matrix may be useful as anti-biofilm agents.<ref>{{cite journal |vauthors=Kaplan JB, Ragunath C, Velliyagounder K, Fine DH, Ramasubbu N |title=Enzymatic detachment of Staphylococcus epidermidis biofilms |journal=Antimicrobial Agents and Chemotherapy |volume=48 |issue=7 |pages=2633–6 |date=July 2004 |pmid=15215120 |pmc=434209 |doi=10.1128/AAC.48.7.2633-2636.2004}}</ref><ref>{{cite journal |vauthors=Xavier JB, Picioreanu C, Rani SA, van Loosdrecht MC, Stewart PS |title=Biofilm-control strategies based on enzymic disruption of the extracellular polymeric substance matrix--a modelling study |journal=Microbiology |volume=151 |issue=Pt 12 |pages=3817–32 |date=December 2005 |pmid=16339929 |doi=10.1099/mic.0.28165-0|doi-access=free }}</ref> Evidence has shown that a fatty acid messenger, [[Cis-2-Decenoic acid|''cis''-2-decenoic acid]], is capable of inducing dispersion and inhibiting growth of biofilm colonies. Secreted by ''[[Pseudomonas aeruginosa]]'', this compound induces cyclo heteromorphic cells in several species of bacteria and the yeast ''[[Candida albicans]]''.<ref>{{cite journal|vauthors=Davies DG, Marques CN |title=A fatty acid messenger is responsible for inducing dispersion in microbial biofilms |journal=Journal of Bacteriology |volume=191 |issue=5 |pages=1393–403 |date=March 2009 |pmid=19074399 |pmc=2648214 |doi=10.1128/JB.01214-08}}</ref>
Nitric oxide has also been shown to trigger the dispersal of biofilms of several bacteria species<ref>{{cite journal|vauthors=Barraud N, Hassett DJ, Hwang SH, Rice SA, Kjelleberg S, Webb JS |title=Involvement of nitric oxide in biofilm dispersal of Pseudomonas aeruginosa |journal=Journal of Bacteriology |volume=188 |issue=21 |pages=7344–7353 |year=2006 |doi=10.1128/jb.00779-06|pmid=17050922 |pmc=1636254 }}</ref><ref>{{cite journal|vauthors=Barraud N, Storey MV, Moore ZP, Webb JS, Rice SA, Kjelleberg S |title=Nitric oxide-mediated dispersal in single- and multi-species biofilms of clinically and industrially relevant microorganisms |journal=Microbial Biotechnology |volume=2 |issue=3 |pages=370–378 |year=2009 |doi=10.1111/j.1751-7915.2009.00098.x|pmid=21261931 |pmc=3815757 }}</ref> at sub-toxic concentrations. [[Nitric oxide]] has potential as a treatment for patients that have chronic infections caused by biofilms.<ref>{{cite web |url=http://www.southampton.ac.uk/biosci/research/projects/dispersal_of_biofilms_in_cystic_fibrosis.page |title=Dispersal of Biofilm in Cystic Fibrosis using Low Dose Nitric Oxide |publisher=University of Southampton |access-date=20 January 2012 |archive-date=8 December 2013 |archive-url=https://web.archive.org/web/20131208120601/http://www.southampton.ac.uk/biosci/research/projects/dispersal_of_biofilms_in_cystic_fibrosis.page |url-status=live }}</ref>

It was generally assumed that cells dispersed from biofilms immediately go into the planktonic growth phase. However, studies have shown that the physiology of dispersed cells from ''Pseudomonas aeruginosa'' biofilms is highly different from that of planktonic and biofilm cells.<ref name="auto">{{cite journal|vauthors=Chua SL, Liu Y, Yam JK, Tolker-Nielsen T, Kjelleberg S, Givskov M, Yang L |title=Dispersed cells represent a distinct stage in the transition from bacterial biofilm to planktonic lifestyles |journal=Nature Communications |volume=5 |year=2014 |doi=10.1038/ncomms5462 |pmid=25042103 |pages=4462|bibcode=2014NatCo...5.4462C |doi-access=free }}</ref><ref name="pmid26158442">{{cite journal | vauthors = Chua SL, Hultqvist LD, Yuan M, Rybtke M, Nielsen TE, Givskov M, Tolker-Nielsen T, Yang L | title = In vitro and in vivo generation and characterization of Pseudomonas aeruginosa biofilm-dispersed cells via c-di-GMP manipulation | journal = Nat Protoc | volume = 10 | issue = 8 | pages = 1165–80 | date = August 2015 | pmid = 26158442 | doi = 10.1038/nprot.2015.067 | hdl = 10356/84100 | s2cid = 20235088 | hdl-access = free }}</ref> Hence, the dispersal process is a unique stage during the transition from biofilm to planktonic lifestyle in bacteria. Dispersed cells are found to be highly virulent against macrophages and ''Caenorhabditis elegans'', but highly sensitive towards iron stress, as compared with planktonic cells.<ref name="auto" />

Furthermore, ''Pseudomonas aeruginosa'' biofilms undergo distinct spatiotemporal dynamics during biofilm dispersal or disassembly, with contrasting consequences in recolonization and disease dissemination.<ref name="Ma 1–13">{{cite journal | vauthors = Ma Y, Deng Y, Hua H, Khoo BL, Chua SL | title = Distinct bacterial population dynamics and disease dissemination after biofilm dispersal and disassembly | journal = The ISME Journal | volume = 17 | issue = 8 | pages = 1290–1302 | date = August 2023 | pmid = 37270584 | pmc = 10356768 | doi = 10.1038/s41396-023-01446-5 | bibcode = 2023ISMEJ..17.1290M }}</ref> Biofilm dispersal induced bacteria to activate dispersal genes to actively depart from biofilms as single cells at consistent velocities but could not recolonize fresh surfaces. In contrast, biofilm disassembly by degradation of a biofilm exopolysaccharide released immotile aggregates at high initial velocities, enabling the bacteria to recolonize fresh surfaces and cause infections in the hosts efficiently. Hence, biofilm dispersal is more complex than previously thought, where bacterial populations adopting distinct behavior after biofilm departure may be the key to survival of bacterial species and dissemination of diseases.

[[File:Honors Option-MMG.svg|thumb|upright=2.5|center| {{center|'''Biofilm dispersal'''{{hsp}}}}]]

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