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    i chose to do my c/wok on the antimicrobial effects of Dettol on m.luteus and e.coli.:cool:

    but i encountered a HUGE problem.
    THis is how i carried out the experiment
    i diluted the dettol with distilled water to make 10%, 40%, 50% and 80% dettol. I innoculated the already made nutrient agar with e.coli....and m.luteus. THen i pippete into the petri-dishes, 3 drops of the different concentrations of dettol and incubated them in 32-37.C ...for few days.

    hyPOTHESIS : I expected 80% dettol PETRI-DISH to have no grown bacteria...or the largest zone of inhibition..but the RESULTS WHERE THE OPPOSITE OF MY HYPOTHESIS.

    10% had litteraly almost NO BACTERIA IN THE Petri-dish.......likewise 40% and 50%...on the other hand .80% petri dish had a green tint to dish and had some cloudy tiny smudges in it....

    1) i think maybe i made a mistake: i sealed the petri-dishes the wrong way around with celotape so it was AIR tight....DO YOU think that was the reason to my bizarre results (because the bacteria respires normally aerobicaly?)?
    2) do you think my results where correct..because maybe 80% of dettol is to0 high that it would actually have no effect on the bacterias cell wall.....:confused:
    3) maybe the dettol actually doesnt affect e.coli and m.luteus....maybe i chose the wrong bacteria for the investigation. IF SO please tell me what bacteria would give a better reliable result.

    I AM SOO CONFUZSED please someone help..and tell me what im doing wrong.....

    tnx
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    how come you didn't do 75%,50%,25%,12.5%??
    this way you could have done serial dilution!
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    Did you do a negative control without any dettol but instead using distilled water by any chance?
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    also 3 drops doesn't seem very accurate, you need to be ensuring every plate has the same quantity of dettol/water mix. Also how well are you mixing the solutions and why aren't you doing a serial dilution? How often did you check the plates during incubation? After around 24hrs some bacteria will start to mutate and become resistant to prolonged antibacterial exposure. You should also have a control of no dettol and control of dettol without innoculated bacteria to ensure contamination isn't occuring.
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    (Original post by aimzdy)
    also 3 drops doesn't seem very accurate, you need to be ensuring every plate has the same quantity of dettol/water mix. Also how well are you mixing the solutions and why aren't you doing a serial dilution? How often did you check the plates during incubation? After around 24hrs some bacteria will start to mutate and become resistant to prolonged antibacterial exposure. You should also have a control of no dettol and control of dettol without innoculated bacteria to ensure contamination isn't occuring.
    PPM > 3 Drops imo :aetsch:
 
 
 
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