Science Project Details:

Disinfectant concentration and bacteria resistance

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Difficulty: Advanced 9
Cost ($): 90
Time required: < 2 weeks
1 day for preparation, 8 days for the science project experiment
Availability of materials:
Access to laboratory equipment (eg. petri dishes)
Required Skills:
Familiarity with handling of bacteria cultures and access to a laboratory  
Safety concerns:

Always follow laboratory safety guidelines and always practice sterile technique when handling microbes. Never have any food or drink at your workstation and always thoroughly wash your hands with disinfectant soap or alcohol before leaving your workstation. Always dispose of used material in a biohazard bag. If none are available, the bacteria should be destroyed with bleach before being disposed of.

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The aim of this science fair project is to find out how the concentration of disinfectants can affect bacteria resistance. The experiment is carried out using different concentrations of Dettol disinfectant.


Lower disinfectant concentrations  cause  the bacteria to develop resistance more quickly.

Scientific Terms

Bacteriaresistance, microorganisms, evolve, genetic, mutation, zone of inhibition


Bacterial resistance

Bacteria and other microorganisms exist all around us. Most of them are harmless to humans. Some assist us in digesting our food while others make us sick. This is why disinfectants should be used regularly to reduce the growth of these harmful bacteria.

However, disinfectant overuse leads to bacteria resistance, whereby the bacteria develops an immunity towards the disinfectant and makes it ineffective in killing the bacteria. This is also true for bacteria resistance towards antibiotics. This may lead to the growth and multiplication of a new population of resistant bacteria.