Skip to 0 minutes and 10 secondsWe often demonstrate the effects of antibiotics on the growth of bacteria and this can easily be placed into everyday context. Analysis of the results enable us to discuss the idea of antibiotic resistance and the different effects of the antibiotics and their specificity. We can add further contexts by looking at other sources of materials which might inhibit bacterial growth. An example is the oligo dynamic effect. This can be introduced by investigating the best metal to have for door handles in hospitals. To do this you need to have a pour plate of B. subtilis. Place different samples of sterile metals onto the plate and incubate. From these results you can see that brass is the best metal for bacterial inhibition.
Skip to 1 minute and 2 secondsThis could lead to an interesting conversation about what hospital door handles are made from and why. Using the context of spot treatments you can investigate the inhibition properties of chemicals such as tea tree oil, garlic and face wash by making discs of filter paper and placing onto a pour plate in exactly the same way you would the for the antibiotic discs.
Inhibition of bacterial growth
In Week 2 we looked at planning for progression in technical skills and scientific understanding. Students also need plenty of opportunities to practice the same skill several times. Varying the context in which practical work is presented allows students to do this throughout the scheme of work whilst making connections with prior learning.
This video shows three common experiments investigating inhibition of bacterial growth, and each would allow students to practice aseptic technique. There are a variety of contexts you can use to introduce the practicals.
In this video several microbiology techniques are mentioned. The Society of General Microbiology, provides a basic introduction to microbiology, aseptic technique and safety manual.
Part 1 of the manual includes information on good microbiological laboratory practice, equipment, preparation of culture media, sterilisation and disinfection, inoculation, aseptic technique, incubation, cultures, contamination and working with moulds, bacteria and yeasts.
Part 2 describes practical activities which students can carry out, such as testing sensitivity to antimicrobial substances.
For a full range of protocols for microbiology practical work, have a look at Practical Microbiology for Secondary Schools, also from the Society of General Microbiology.
Although antibiotic resistance and the development of new antibiotics may be in the news, it can be quite far removed from the life of an average teenager. However, most students will be familiar with cleaning products which claim to kill germs, or antibacterial facial wash.
In the next step we suggest how a little bit of lateral thinking and drawing upon cultural myths can spark debates in your class that draw upon scientific concepts.