Disinfection

PEEBLESHS peebleshs at aol.com
Tue Nov 9 10:39:05 EST 1999


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.




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