What Are Biofilms?

  • Have you ever pick up a rock from a nearby stream and wondered why it’s slimy on the surface? That slimy layer is actually a group of microorganisms, collectively called a biofilm.
  • A biofilm is a community of bacteria that attach to a surface by excreting a sticky, sugary substance that encompasses the bacteria in a matrix.
  • This might be the first time you’ve heard the term biofilm, but they’re actually all around us, in streams, in drains, in fish tanks, even on our teeth.
  • A biofilm can be composed of a single species or a conglomerate of species.
  • In many cases, biofilms are only bacteria, but they can also include other living things such as fungi and algae, creating a microbial stew of sorts. Biofilms are complex systems that are sometimes compared to multicellular organisms.

How Are Biofilms Formed?

  • Biofilm formation begins with planktonic, or free-swimming, bacteria, which land on a surface. Bacteria can attach to a variety of surfaces, from woods, metals and plastics to living tissues and stagnant water.
  • The cells are able to attach to the surface by excreting a sugary molecule that holds the cells together and attaches them to the surface.
  • This sugary substance is called extracellular polymeric substance, or EPS, and has a strand like structure that allows it to bind to the surface and to other cells, creating a matrix.
  • This matrix of cells and strands can be quite complex: the cells may even share genetic material and have organized structure.
  • A biofilm can be as thin as a single cell or as thick as several inches, depending on conditions in the environment.
  • As a biofilm grows and develops, it thickens and becomes mature.
  • If there is sufficient water and nutrients, the biofilm will develop until small portions detach and float to another surface and colonize.

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