Schoolzone: Blast a Biofilm – a hands-on activity

Blast a Biofilm is an activity developed by Microbiology Society members Victoria Marlow and 2011 Microbiology Outreach Prize Winner Nicola Stanley-Wall (based on an idea by Taryn Kiley) as part of Magnificent Microbes, an event held at Dundee Science Centre in 2010. This hands-on activity was adopted and adapted by the Society’s Education and Outreach Officer for this year’s Big Bang Fair. Here, we explain how it’s done and invite you to have a go!

VICKI SYMINGTON

Aimed at children and adults with little or no knowledge of microbiology, this activity introduces the concept of biofilms by inviting participants to build biofilms and then attempt to ‘blast’ them away. Focussing on the topic of antibiotics, it helps highlight the healthcare-associated problems posed by biofilms. This activity works well in the classroom and at public science events.

Getting started

Biofilm blasting with Magnificent Microbes In their natural environments, bacteria do not often exist as the single isolated bacterial cells that are observed in laboratory cultures. In nature, they live in highly organised communities called biofilms.     A biofilm is an encased community of microbial cells that are attached to a surface by a gelatinous adhesive, which the microbial cells excrete. The adhesive consists of extracellular polymeric substances (EPS) that provide a matrix for the microbes, holding them together as well as anchoring them to surfaces.     Micro-organisms in biofilms are protected from many forms of chemical treatment (antibiotics, biocides and disinfectants), grazing organisms and – where relevant – the host’s immune system. The biofilm provides microbes with nutrition, gas exchange and a system for removal of waste products.

First, establish prior knowledge of microbes or biofilms by discussing common biofilms and any familiar features, such as their sticky appearance for example, leading on to an understanding that the sticky matrix that holds biofilms together protects them from antibiotics and, in the case of biofilms on or in the body, the host’s immune system.

To build your biofilm you will need:

• Model microbes of different colours, shapes and sizes (these models can be made from modelling clay - we used STAEDTLER® FIMO® modelling clay) (see image above)
• Hair gel labelled ‘matrix’
• A high-sided tray to contain the activity
• 1–2 plastic containers

To blast your biofilm you will need:

• A water pistol (what else!) labelled ‘Antibiotics’

To set up the activity:

• place the containers upside-down inside the tray (these will be the surfaces to which the biofilms will attach). Have your ‘microbes’, ‘antibiotics’ and ‘matrix’ close to hand.

Get blasting!

Make and blast biofilms by:

• Placing microbes onto the plastic containers
• Covering one set of the microbes with matrix
• Blasting the microbes using the ‘antibiotics’, taking care to observe and explain the difference between the presence and absence of matrix.

During or following the blasting, you may like to discuss the positive and negative implications of biofilm production, along with where you may find biofilms. The resistance of biofilms to antibiotics can be directly compared to planktonic microbes in this hands-on activity and can contribute to knowledge and an understanding of microbes to support curriculum-related topics and enhance understanding of this important area of microbiology. Blast a Biofilm is currently being developed into an educational resource by Nicola and Victoria.

Blasting Biofilms at Big Bang

This activity, developed by Nicola, Victoria and Taryn, can be used to effectively communicate messages such as the importance of good oral hygiene. We took the opportunity to partner this activity with our comic – Marvellous Microbes: A trip to the dentist – for our activity at the Big Bang Fair this year. We adapted the activity by using strips of ice-cube trays to represent teeth and, when blasting with water pistols, discussed the action of saliva in the mouth. We also used some giant toothbrushes to brush the bacteria away!

Plaque Attack!

In addition to Blast a Biofilm, we offered Plaque attack: giving bacteria the brush off, an activity to demonstrate removal of plaque (simulated by using a thick cornflour and water paste) from giant teeth models and from the teeth of phantom heads (kindly supplied by A-dec) using manual, electric and giant toothbrushes. In this activity, we talked about the different environments in the mouth where plaque may ‘hide’. We also showed the effect of toothpaste (and plaque acid) on teeth using eggs as models (see the ‘Egg-speriment’ which accompanies the Marvellous Microbes comic strip, available to download from our education website).

When talking about biofilms, you could even make a model biofilm using lemon jelly and some of the model bacteria as shown in the figure above. (Immunology News, August 2012).

These activities require no specialised equipment and provide simple, fun ways to introduce this familiar area of microbiology, clearly developing an understanding of the importance of microbes and biofilms in our everyday lives. If you are interested in having a go with any of these activities yourself, get in touch with our Education Office for advice ([email protected]).

VICKI SYMINGTON, SGM