I am a sixth year pupil at Peebles High School, Scotland. For my Sixth Year
Studies Biology project I have been investigating the effects of different
disinfectants on E.Coli, Bacillus Subtilis and Micrococcus Luteus. I have
altered the concentrations of bleach and Dettox and found that concentrations
of less than 0.0001% bleach and 0.001% Dettox stimulate bacterial growth. Can
anyone tell me why this happens? I found that a 5% phenol solution was very
effective against M. Luteus but ineffective against E.Coli. E.Coli was also
very resistant to Rossopol - a washing up liquid. Hydrogen peroxide was very
effective against all three bacteria. Can anyone explain these findings. I am
also interested to know exactly how these disinfectants work - what do the
terms anionic, cationic and non-ionic mean when applied to disinfectants? Also
any other useful information.
