My Name is Sinthi Tharmalingam and I complete a project called Reek-coli for my science fair at my school. This is the scientific method that I used for my project:
Problem:
To find the effect of Allium sativum (garlic) extract on Escherichia coli (E. coli) bacteria
Hypothesis:
I believe that higher concentrations of garlic on E. coli samples may inhibit the growth of E. coli bacteria
Materials:
For my first experiment I used: Savlon(disinfectant/liquid soap)
Mortar and pestle
Antibacterial hand soap
Agar dishes
9 grams of garlic
Pipette
Digital scale
E. coli culture
Stop watch
20 tubes to dilute
E. coli
Graduated cylinder
Glass rod
Bunsen burner
20 C incubator}
Distilled water
95%}alcohol ethanol approx. 100 ml
For my second experiment I used:
Savlon (disinfectant/liquid soap)
Cheese cloth
Antibacterial hand soap
Beaker
22.5 grams of garlic
E. coli Culture
Digital scale
Pipette
Stop watch
24 test tubes
Distilled water
Bunsen burner
95% alcohol ethanol approx.100 ml
20 C incubator
Mortar and pestle
14 agar dishes
Graduated cylinder
Calculator
Procedure
Experiment #1 - Garlic Extract
1) Gathered materials
2) Cleaned tabletop with savlon soap and washed hands with antibacterial hand soap
3) Measured 9g of skinned garlic on digital scale
4) Put garlic into graduated cylinder and poured ethanol over garlic (enough to cover all garlic)
5) Set stop watch at 2 minutes
6) After 2 minutes, poured alcohol into the sink
7) Rinse garlic with distilled water 5-6 times (use approx. 40 ml per wash)
8) Sterilized mortar and pestle with ethanol
9) Rinsed out mortar and pestle with distilled water 10) Crushed garlic into a paste with mortar and pestle
11) Added 12 ml distilled water to form a puree
Experiment #1 - E. coli preperation
1) Put 4.5 ml water into each of the ten test tubes
2)Added .5 ml E. coli to 4.5 ml water
3) Transferred .5 ml diluted E. coli into 4.5 ml water until 10 times diluted ( see diagrams)
Experiment #1- Plating Dishes
1) Labelled every dish
2) Dipped glass rod into ethanol and flamed it (to sterilize)
3) Plated .5 ml of diluted E.coli bacteria into agar dishes and spread the E. coli around the dish with the sterilized glass rod
4) Used pipette to distribute garlic samples to agar
Experiment #2 - Garlic Extract
1) Cleaned work surface with savlon soap
2) Measured 22.5 grams of peeled garlic cloves
3) Submerged garlic with 95% ethanol in graduated cylinder for 2 minutes
4) Sterilized mortar and pestle with ethanol for 2 minutes
5) After 2 minutes, poured the ethanol down the sink
6) Rinsed garlic cloves and mortar and pestle 5 times with distilled water
7) Crushed and ground garlic cloves
8) Slowly added 50 ml of water and ground into paste
9) Poured paste through cheese cloth into graduated cylinder
10) Squeezed entire contents
11) Collected 66 ml of extract
Experiment #2 - Serial Dilution
1) Collected 10 test tubes each with 9 ml water
2) Completed serial dilution by putting 1 ml E. coli into 9 ml water (tube 1)
3) Put 1 ml of E. coli and water mixture from tube 1 into tube 2
4) Mixed tube 2
5) Collected 1 ml from tube 2 and added it to tube
6) Repeated steps 4 and 5 until tube 10
Experiment #2 - Serial Dilution
1) Plated .1 ml of test tubes 10 -6 to 10-10 into agar dishes
2) Incubated 5 plates in 370 C for 24 hours
3) Collected culture of E. coli
4) Added 1 ml of culture to test tubes A - F (see diagram)
5) Put 1 ml of 10 -1 E. coli culture into test tubes A2 - F2
6) Added garlic samples to test tubes according to chart (see Ex #2 substance level chart)
7) Added sterile water according to chart (see Ex #2 substance level chart)
8) Put test tube solutions into 370 F (200 C) incubator for approximately 24 hours
9) Plated .1 ml incubated test tube solutions
10) Put plates into incubator at 370F (200 C) for 24 hrs
Results:
Observations:
I observed that;
- All of the agar dishes had a foul odour
- Most of the dishes got contaminated
- Each set of two dishes had different results
- E. coli looks like white circular, pulvinate, entire, shiny and glossy, and viscid colonies about 2 mm in diameter
- See chart for further information
Interpretation Of Results;
(Experiment #1) In my first experiment I believe that I contaminated either the extract or I left the dishes open and the air left some bacteria. I believe that the extract got contaminated, because of poor sterilization of the equipment. I realized that the dishes had got contaminated because of the various sizes, shapes and colours of colonies. In my next experiment I hope that I can detect the contamination and therefore prevent it before I plate the dishes.
Observations (Experiment #2):
I observed that;
Test tube G and G2 turned green
The other test tubes had turned a pale yellow colour
The test tubes were all foggy
Plated dish C didn't have as much bacteria as dish D
See pictures for test tube results
See chart for plated results
Interpretation Of Results;
(Experiment #2) My second experiment displayed that garlic does inhibit the growth of bacteria. The results were very accurate in showing this, because of the equal decreasing amount of colonies per each agar dish. It also shows that contamination did not occur because the similarities of the colonies. Although, test tubes G and G2 contained a couple of colonies which are most likely to be good bacteria because of their different colonial characteristics. The colonies were raised instead of pulvinate, and irregular instead of circular.
Conclusion
From my second experiment, I conclude that Garlic does inhibit the growth of E. coli bacteria. Therefore,I accept my hypothesis, I believed that higher concentrations of garlic would have an effect on E. coli. My results show that even the slightest amount of garlic extract has a little effect on E. coli growth.
Application
I learned a lot of information from this experiment. I hope that everyone will benefit from this experiment by realizing that taking chemical filled medication isn't always the best answer. Garlic is inexpensive, more healthier, and doesn't have side effects. It is available in a pill format, but eating it raw is more beneficial because the pill usually contains preservatives.
PROJECT COMPLETED
BY:
SINTHI