Editing Biofilm (section)

====Intercellular communication====
{{See also|Oral microbiology}}
A peptide pheromone quorum sensing signaling system in ''[[S. mutans]]'' includes the [[Oral microbiology#Intercellular communication|competence stimulating peptide]] (CSP) that controls genetic competence.<ref name="Li">{{cite journal|date=February 2001|title=Natural genetic transformation of Streptococcus mutans growing in biofilms|journal=J. Bacteriol.|volume=183|issue=3|pages=897–908|doi=10.1128/JB.183.3.897-908.2001|pmc=94956|pmid=11208787|vauthors=Li YH, Lau PC, Lee JH, Ellen RP, Cvitkovitch DG}}</ref><ref name="pmid18792689">{{cite book|year=2008|series=Advances in Experimental Medicine and Biology|volume=631|pages=[https://archive.org/details/bacterialsignalt0000unse/page/178 178–88]|doi=10.1007/978-0-387-78885-2_12|isbn=978-0-387-78884-5|pmid=18792689|vauthors=Senadheera D, Cvitkovitch DG|chapter=Quorum Sensing and Biofilm Formation by Streptococcus mutans |title=Bacterial Signal Transduction: Networks and Drug Targets|chapter-url=https://archive.org/details/bacterialsignalt0000unse/page/178}}</ref> Genetic competence is the ability of a cell to take up DNA released by another cell. Competence can lead to genetic transformation, a form of sexual interaction, favored under conditions of high cell density and/or stress where there is maximal opportunity for interaction between the competent cell and the DNA released from nearby donor cells. This system is optimally expressed when ''S. mutans'' cells reside in an actively growing biofilm. Biofilm grown ''S. mutans'' cells are genetically transformed at a rate 10- to 600-fold higher than ''S. mutans'' growing as free-floating planktonic cells suspended in liquid.<ref name="Li" />

When the biofilm, containing ''S. mutans'' and related oral streptococci, is subjected to acid stress, the competence regulon is induced, leading to resistance to being killed by acid.<ref name="Lemos" /> As pointed out by Michod et al., transformation in bacterial pathogens likely provides for effective and efficient recombinational repair of DNA damages.<ref name="Michod">{{cite journal|date=May 2008|title=Adaptive value of sex in microbial pathogens|journal=Infect. Genet. Evol.|volume=8|issue=3|pages=267–85|doi=10.1016/j.meegid.2008.01.002|pmid=18295550|vauthors=Michod RE, Bernstein H, Nedelcu AM|bibcode=2008InfGE...8..267M }}http://www.hummingbirds.arizona.edu/Faculty/Michod/Downloads/IGE%20review%20sex.pdf {{Webarchive|url=https://web.archive.org/web/20200511153411/http://www.hummingbirds.arizona.edu/Faculty/Michod/Downloads/IGE%20review%20sex.pdf |date=11 May 2020 }}</ref> It appears that ''S. mutans'' can survive the frequent acid stress in oral biofilms, in part, through the recombinational repair provided by competence and transformation.

'''Predator-prey interactions'''

{{See also|Lotka–Volterra equations|l1=Predator-prey interactions}}

[[Predation|Predator]]-[[Predation|prey]] interactions between biofilms and bacterivores, such as the soil-dwelling nematode ''[[Caenorhabditis elegans]],'' had been extensively studied. Via the production of sticky matrix and formation of aggregates, ''[[Yersinia pestis]]'' biofilms can prevent feeding by obstructing the mouth of ''C. elegans''.<ref>{{cite journal | vauthors = Atkinson S, Goldstone RJ, Joshua GW, Chang CY, Patrick HL, Cámara M, Wren BW, Williams P | title = Biofilm development on Caenorhabditis elegans by Yersinia is facilitated by quorum sensing-dependent repression of type III secretion | journal = PLOS Pathogens | volume = 7 | issue = 1 | pages = e1001250 | date = January 2011 | pmid = 21253572 | pmc = 3017118 | doi = 10.1371/journal.ppat.1001250 | doi-access = free }}</ref> Moreover, ''[[Pseudomonas aeruginosa]]'' biofilms can impede the slithering motility of ''C. elegans'', termed as 'quagmire phenotype', resulting in trapping of ''C. elegans'' within the biofilms and preventing the exploration of nematodes to feed on susceptible biofilms.<ref>{{cite journal | vauthors = Chan SY, Liu SY, Seng Z, Chua SL | title = Biofilm matrix disrupts nematode motility and predatory behavior | journal = The ISME Journal | pages = 260–269 | date = September 2020 | volume = 15 | issue = 1 | pmid = 32958848 | doi = 10.1038/s41396-020-00779-9 | pmc = 7852553 | url = }}</ref> This significantly reduced the ability of predator to feed and reproduce, thereby promoting the survival of biofilms. ''Pseudomonas aeruginosa'' biofilms can also mask their chemical signatures, where they reduced the diffusion of quorum sensing molecules into the environment and prevented the detection of ''C. elegans''.<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 | volume = 16 | issue = 5 | pages = 1388–1396 | date = May 2022 | pmid = 35034106 | pmc = 9038794 | doi = 10.1038/s41396-022-01190-2 | bibcode = 2022ISMEJ..16.1388L }}</ref>