Build a Biofilm

Build a biofilm was an activity developed by Rachel Sammons and Sarah Kuehne for the Slime Cities exhibition. It is s a craft based activity exploring what makes up dental plaque that forms a biofilm on our teeth.

Bacteria grow on the teeth and are the reason we should clean our teeth for 2min twice a day. If the plaque is not cleaned off it might lead to problems in the mouth like tooth decay (dental caries) or to gum disease (gingivitis or periodontitis).



Bacteria come in lots of shapes, for example spheres, rod shapes and spirals. Examples of these in the mouth are called Streptococci, Lactobacilli or Treponema species. Streptococcus mutans is a key species involved in dental caries or tooth decay. Lactobacillus acidophilus is an example of Lactobacillus found in the mouth. Treponema denticola is associated with gum disease (or periodontitis). In the mouth more than 700 species have been identified but the average person has about 200 different types present. They can change with time, diet and habits (such as smoking).

The bacteria in plaque live in a community called a biofilm and this is held together by the extracellular polysaccharide (EPS) matrix. This gooey material can make it harder to get biofilms off surfaces, including our teeth.

The immune system is always checking out the biofilm in the mouth. White blood cells called neutrophils will be the most common type. These cells contain powerful antimicrobial chemicals that they can use to try and kill off the biofilm bacteria.

You will need:

mini pompoms in multi colours for bacteria

white pompoms for white blood cells

wool tops for extracellular polysacharide (EPS)

pipe cleaners – cut to approx 1.5cm and also some approx 5cm

PVA glue


box or card to stick your biofilm to

Clingfilm (optional)



Start by taking the box or card and adding glue to the surface. Then add some mini pompoms and the shorter pieces of pipe cleaner. These represent the bacteria in the biofilm that are spheres and rods. Using the pencil (or your finger) make spirals with the longer pieces of pipe cleaner to make spiral shaped bacteria. Add these to the box too.

Then tease off a little wool. If you don’t have wool tops then bits of cotton wool balls or other fluffy type stuff will work well too. Add this on top of the bacteria. Poke it around them to get it in the glue too.

Lastly add one or two white pompoms. These represent the white blood cells that will come to check out the biofilm and may be try and get rid of it.

If you are going to transport it just after making then wrap the box in a little clingfilm to help keep everything in place. If you’re not going anywhere you can just let it dry.

Here is a little video we made of Rachel building a biofilm. Rachel has an undergradudate degree in Biological Sciences and a PhD in Microbial Genetics. She first got interested in microbes when she got given a microscope as a child and has been hooked ever since!




Rachel often studies bacteria and biofilms using a special microscope called a scanning electron microscope. This uses electrons to be able to see bacteria in unprecedented detail. This imagebelow shows the plaque biofilm (in green and yellow) with white blood cells (purple) on top. In reality it is just in black and white and we can add colour by painting it on in the computer. If you would like to colour your own in try out this colour a biofilm.

Dental plaque 2