Details for this experiment

Aim: this experiment has two inter-related aims:
1) to find out if antibacterial hand soap really kills as much bacteria as claimed, with comparison to normal hand soap.
2) to find out if there can be an alternative for hand soap in lime juice and lemon juice that kills as much bacteria as the antibacterial hand soap or at least the normal hand soap.
(Research to back up experiment aim: citric acids are able to kill/inhibit bacteria by breaking down their cell membranes.
And even though the mechanism of removing bacteria using normal hand soap and antibacterial hand soap is a bit different, it would still be interesting to find out if what is supposed to happen in theory really does happen in products of the market.)


Materials and Apparatus:
10 petri-dishes of agar jelly for bacteria culture
Pure lime juice
Pure lemon juice
Distilled water
Normal hand soap
Hand soap that claims to kill 99.9% of bacteria (probably Dettol brand)
Sterilized cotton swabs
Sterilized droppers
Masking tape
Bacteria culture machine (in where bacteria can breed well)

Procedure:
1, Prepare 8 petri dishes of agar jelly-based bacteria culture. (Even though only 5 would be used later, the extra cultures are to make sure if there are cultures that do not turn out well enough for experiment, there would be replacements. If the logistics are available, that is.) Wet sterilized cotton wipes with sterilized/distilled water and swipe from the hand three strokes systematically. Spread evenly on the agar jelly of Petridish 1. Close the lid on the sample immediately after this is done.

2, Do the same for all other petri-dishes.

3, Seal each petri-dish with masking tape.

4, Put all petri-dishes in the bacteria culture machine (?) and let the bacteria develop for 24 hours. (?)

5, In the mean time, measure the pH of pure lime juice, pure lemon juice, distilled water, normal liquid hand soap and 99.9% bacteria-killing hand soap using pH test paper.

6, Also draw up a chart to measure the amount of bacteria by classifying colonies according to their diameters of 1mm, 2mm, 5mm, etc.

7, Back to the lab-select 5 petri-dishes of bacteria culture that are the most desirable (criteria: with distinctive  colonies of bacteria for easy counting, with only bacteria and no mould on it). Measure the amount of bacteria on it by counting using the classifying chart of colony sizes.

8, Measure out 50mm of each type of liquid using a sterilized dropper and place each liquid onto a sterilized cotton swab. (using different uncontaminated droppers if possible).

9, Spread out the lime juice evenly onto one petri-dish using the cotton swab. Label this clearly 'Sample Lime Juice'.

10, Do similarly for different test liquids.

11, Seal the petri-dishes back and replace them into the bacteria culture machine for another 24 hours.

12, After 24 hours, observe and measure the amount of bacteria on each sample again.

13, 24 hours after this,  observe and measure the amount of bacteria on each sample again.

14, After yet another 24 hours, observe and measure the amount of bacteria on each sample again.

15, Record and analyse all findings. Calculate the percentage change in the amount of bacteria as this would be more accurate. Present data in a clear table and/or graph.

That is the methodology. There seem to be many areas to do further research on.
1) Are 24 hours enough/suitable for enough cell development to be the interval between observation taken of bacteria?
2) Is the school lab open on Sundays?
3) What kind of bacteria is likely to be present on our hands?
4) What if i encounter different kinds of bacteria (those of different colours)? the experiment would be more interesting.......