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Bacteria produce something called a biofilm.

I have found a few definitions; some say it is a complex of live and dead bacteria and others say it is a layer on cell wall.

  1. What is it made of?
  2. What is its purpose?
  3. How do we combat biofilms when we encounter them?
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Why would you want to combat them universally? Some do us harm (e.g., the plaque on our teeth) but most are essential for the functioning of the biosphere. –  KennyPeanuts Apr 14 '13 at 16:37
    
Hi Kenny. I dont. I just like to know about them universally ;) –  MySky Apr 17 '13 at 6:04
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2 Answers

Aside from the actual microbial cells themselves, biofilms are a slime matrix made of a variety of substances, including DNA, lipids, proteins, and other signaling molecules, but the major component is something called extracellular polymeric substance (EPS), also known as exopolysaccharides. Sinorhizobium meliloti monosuccinylated succinoglycan Succinoglycan from Sinorhizobium meliloti

These are high molecular weight extracellular (exo) polymers (poly) of sugars (saccharides) linked together into long linear or branched chains, which can be modified by moieties such as phosphate, sulfate, acetate, and succinate. As the biofilm forms (below), channels can form in the EPS to facilitate nutrient uptake and distribution, hydration, and inter-cellular signaling such as quorum sensing. Biofilms are often composed of multiple species of microorganisms, from bacteria and archaea to fungi and algae, with the social (and physical) structure dependent on the species that compose it.

Biofilm formation

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Bacterial biofilms are a bunch of bacteria that have attached themselves to a surface or to each other as a floating mat to form a solid phase community. Its not seen in the lab so much, but they are common in nature.

The bacteria not only adhere to the surface, but each other through a matrix of polymers they secrete.

The bacteria in a biofilm are often resistant to chemicals, heat, acid and other changes in the environment. Its a practically universal trait and its generally assumed that any bacteria can form a biofilm. Dental Plaque is a biofilm.

Getting a biofilm eradicated can be a lot of work because the bacteria are sequestered in the matrix and somewhat protected. Scrubbing or chemicals are usually used.

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I'd add that Variovorax (jgi.doe.gov/sequencing/why/100320.html) is a biofilm producer that grows biofilms nicely in the lab. –  kmm Apr 12 '13 at 21:28
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just saw this now - a major regulatory switch that causes biofilm formation was discovered. sciencedaily.com/releases/2013/04/130412132413.htm –  shigeta Apr 12 '13 at 22:09
    
also FYI E coli can form biofilms... ncbi.nlm.nih.gov/pmc/articles/PMC2864707 –  shigeta Apr 12 '13 at 22:10
    
biofilm is a sort of bacteria's small attempt towards multicellularity.. biofilm is not just a layer of bacteria.. it is a system in which different bacteria can assume different roles –  WYSIWYG Apr 13 '13 at 6:25
    
indeed it has structure and different individuals appear to have different roles (or at least genetic activity). E coli form bacterial slugs as well... See Howard Berg's work.. :) –  shigeta Apr 13 '13 at 19:31
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