Disinfectant concentration and bacteria resistance
The hypothesis that a lower concentrationof disinfectant accelerates the development of bacteria resistance is is proven to be false. However, it takes a long period of time before bacteria resistance may be observed, hence this experiment may have to be repeated many times over for any observable results.
The excessive use of disinfectants can engender bacteria resistance such that the disinfectant becomes ineffective in killing bacteria. The development of more resistant strains of bacteria means that stronger concentrations of disinfectants have to be used in order for it to be potent in controlling bacteria growth. This may have adverse consequences as strong concentrations of disinfectants are harmful to humans and the environment.
The science fair project can be repeated by varying the types of disinfectants used, such as antibacterial soaps, Listerine or bleach.Try testing the resistance of various other kinds of bacteria.
Why is bacillus resistant to disinfectants? - http://www.ehow.com/how-does_5173187_bacillus-resistant-disinfectants_.html
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.