Biofilm

IUPAC definition

Aggregate of microorganisms in which cells that are frequently embedded within a self-produced matrix of extracellular polymeric substances (EPSs) adhere to each other and/or to a surface.

  • A biofilm is a system that can be adapted internally to environmental conditions by its inhabitants.
  • The self-produced matrix of extracellular polymeric substances, which is also referred to as slime, is a polymeric conglomeration generally composed of extracellular biopolymers in various structural forms.[1]

A biofilm is a syntrophic community of microorganisms in which cells stick to each other and often also to a surface.[2][3][4] These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular polymeric substances (EPSs).[2][3] The cells within the biofilm produce the EPS components, which are typically a polymeric combination of extracellular polysaccharides, proteins, lipids and DNA.[2][3][5] Because they have a three-dimensional structure and represent a community lifestyle for microorganisms, they have been metaphorically described as "cities for microbes".[6][7]

Biofilms may form on living (biotic) or non-living (abiotic) surfaces and can be common in natural, industrial, and hospital settings.[3][8] They may constitute a microbiome or be a portion of it. The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism, which, by contrast, are single cells that may float or swim in a liquid medium.[9] Biofilms can form on the teeth of most animals as dental plaque, where they may cause tooth decay and gum disease.

Microbes form a biofilm in response to a number of different factors,[10] which may include cellular recognition of specific or non-specific attachment sites on a surface, nutritional cues, or in some cases, by exposure of planktonic cells to sub-inhibitory concentrations of antibiotics.[11][12] A cell that switches to the biofilm mode of growth undergoes a phenotypic shift in behavior in which large suites of genes are differentially regulated.[13]

A biofilm may also be considered a hydrogel, which is a complex polymer that contains many times its dry weight in water. Biofilms are not just bacterial slime layers but biological systems; the bacteria organize themselves into a coordinated functional community. Biofilms can attach to a surface such as a tooth or rock, and may include a single species or a diverse group of microorganisms. Subpopulations of cells within the biofilm differentiate to perform various activities for motility, matrix production, and sporulation, supporting the overall success of the biofilm.[14] The biofilm bacteria can share nutrients and are sheltered from harmful factors in the environment, such as desiccation, antibiotics, and a host body's immune system. A biofilm usually begins to form when a free-swimming, planktonic bacterium attaches to a surface.[15]

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  2. ^ a b c López D, Vlamakis H, Kolter R (July 2010). "Biofilms". Cold Spring Harbor Perspectives in Biology. 2 (7): a000398. doi:10.1101/cshperspect.a000398. PMC 2890205. PMID 20519345.
  3. ^ a b c d Hall-Stoodley L, Costerton JW, Stoodley P (February 2004). "Bacterial biofilms: from the natural environment to infectious diseases". Nature Reviews. Microbiology. 2 (2): 95–108. doi:10.1038/nrmicro821. PMID 15040259. S2CID 9107205.
  4. ^ Bamford, Natalie C, MacPhee, Cait E, Stanley-Wall, Nicola R (August 2023). "Microbial Primer: An introduction to biofilms – what they are, why they form and their impact on built and natural environments". Microbiology. 169 (8): 001338. doi:10.1099/mic.0.001338. PMC 7615007. PMID 37526065.
  5. ^ Aggarwal S, Stewart PS, Hozalski RM (January 2016). "Biofilm Cohesive Strength as a Basis for Biofilm Recalcitrance: Are Bacterial Biofilms Overdesigned?". Microbiology Insights. 8 (Suppl 2): 29–32. doi:10.4137/MBI.S31444. PMC 4718087. PMID 26819559.
  6. ^ Watnick P, Kolter R (May 2000). "Biofilm, city of microbes". Journal of Bacteriology. 182 (10): 2675–9. doi:10.1128/jb.182.10.2675-2679.2000. PMC 101960. PMID 10781532.
  7. ^ "Building Codes for Bacterial Cities | Quanta Magazine". Quanta Magazine. Archived from the original on 26 July 2017. Retrieved 25 July 2017.
  8. ^ Lear G, Lewis GD, eds. (2012). Microbial Biofilms: Current Research and Applications. Caister Academic Press. ISBN 978-1-904455-96-7.
  9. ^ O'Toole GA, Kolter R (May 1998). "Initiation of biofilm formation in Pseudomonas fluorescens WCS365 proceeds via multiple, convergent signalling pathways: a genetic analysis". Molecular Microbiology. 28 (3): 449–61. doi:10.1046/j.1365-2958.1998.00797.x. PMID 9632250. S2CID 43897816.
  10. ^ O'Toole GA, Kolter R (October 1998). "Flagellar and twitching motility are necessary for Pseudomonas aeruginosa biofilm development". Molecular Microbiology. 30 (2): 295–304. doi:10.1046/j.1365-2958.1998.01062.x. PMID 9791175. S2CID 25140899.
  11. ^ Karatan E, Watnick P (June 2009). "Signals, regulatory networks, and materials that build and break bacterial biofilms". Microbiology and Molecular Biology Reviews. 73 (2): 310–47. doi:10.1128/MMBR.00041-08. PMC 2698413. PMID 19487730.
  12. ^ Hoffman LR, D'Argenio DA, MacCoss MJ, Zhang Z, Jones RA, Miller SI (August 2005). "Aminoglycoside antibiotics induce bacterial biofilm formation". Nature. 436 (7054): 1171–5. Bibcode:2005Natur.436.1171H. doi:10.1038/nature03912. PMID 16121184. S2CID 4404961. (primary source)
  13. ^ An D, Parsek MR (June 2007). "The promise and peril of transcriptional profiling in biofilm communities". Current Opinion in Microbiology. 10 (3): 292–6. doi:10.1016/j.mib.2007.05.011. PMID 17573234.
  14. ^ Momeni B (June 2018). "Division of Labor: How Microbes Split Their Responsibility". Current Biology. 28 (12): R697 – R699. Bibcode:2018CBio...28.R697M. doi:10.1016/j.cub.2018.05.024. PMID 29920261. S2CID 49315067.
  15. ^ Case C, Funke B, Tortora G. Microbiology An Introduction (tenth ed.).
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