Some believe that mint can assist in cancer treatments. Studies on animals show that the alcohols present in mint can help prevent colon, lung and skin cancer (Benefits of Mint). The findings are yet to be replicated in human subjects.
Mint is a very common flavoring. We will find mint-flavored toothpaste, mouthwash, gum, chocolate, liquor and hard candies. Mint has a very soothing taste and is commonly used to add to the flavors of cherry, grape and lemon. It also appears in teas and other beverages. Some recipes for entrees (for example, lamb with a mint julep side) also contain mint. Mint also could be the solution for an upset stomach or for a fresh tasting dessert.
Garlic
Figure 4: Garlic (Garlic)
Some of the old stories of garlic's healing properties have doubtful validity, but many of its claimed health benefits have been backed up by modern scientific research. There are two main medicinal ingredients which produce the garlic health benefits: allicin and diallyl sulphides (Garlic Health Benefits).
Modern science has shown that garlic is a powerful natural antibiotic, albeit broad-spectrum rather than targeted. The bacteria in the body do not appear to evolve resistance to the garlic as they do to many modern pharmaceutical antibiotics. This means that its positive health benefits can continue over time rather than helping to breed antibiotic resistant "superbugs". Amongst the most interesting potential applications are suggestions that garlic might be able to assist some people in the management of blood pressure cholesterol levels.
Studies have also shown that garlic, especially aged garlic can have a powerful antioxidant effect. Antioxidants can help to protect the body against damaging free radicals. There are claims that fermented black garlic contains even higher antioxidant levels than normal cloves.
Aim
To investigate antimicrobial properties of plants.
Problem statement
What plant has the highest antimicrobial property??
Hypothesis
The bigger the area of inhibition zone, the higher the antimicrobial properties of plants.
Variables
Manipulated : Type of bacteria used, type of plant extract
Responding : Area of the inhibition zone.
Fixed : The alcohol used, the volume of bacterial broth and agar used, the environment conditions, concentration of plant extract.
Materials
Escherichia coli, and Bacillus subtilis bacterial broth in sterile bijou bottles, agar warmed at 60ºC, distilled water, sterile paper discs, petri dishes, micropipette with sterile tips, test tubes, vortex machine, mortar and pestle, forceps and beaker include the ginger, cinnamon, mint and garlic.
Apparatus
Bunsen burner, autoclaved forceps, eye protection, positive displacement pipette.
Procedures
Preparing the agar plates.
- Hands and the experiment’s place were washed before performing the experiment using disinfectant and detergent.
Figure 6: Clean and wash experiment’s place
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2 sterile petri dishes were labeled accordingly. 2 petri dishes were prepared for each type of bacteria, Escherichia coli, and Bacillus Subtilis.
Figure 7: Labelled the petri dish
- The agar solution, which was kept at 60˚C (for it to be in liquid form), was prepared using the aseptic technique.
- Using the last finger, the bottle containing the agar was opened, and the agar was poured until enough to cover the bacteria. This procedure has to also be done with precautions to prevent the agar from splashing to the sides as it will promote the growth of other microorganisms,such as fungi.
Figure 8: Heat the agar bottle at the mouth after and before use it
- The bacterial broth was then pipette using a micropipette, which has been calibrated to 200µml. The knob of the micropipette was gently pressed and released so that there would not be any air bubbles present in it.
Figure 9: The micropipette
- The bacterial broth was then dispensed in a petri dish labeled accordingly. It was the quickly closed to avoid contact with air too long.
- The mixture of agar and bacteria was placed near the Bunsen burner to let the agar solidified itself.
- Step 5 to 7 was repeated for each bacterium.
Preparation of plant extract.
- 4 types of plant extract were chosen namely ginger, cinnamon, mint and garlic.
- Garlic, ginger and mint had to be pounded using mortar and pestle while cinnamon has been provided in the powdered form.
- The plant extract had to be prepared in a 30% solution. This is done by dissolving 0.3g of each extract in 1 ml of alcohol.
- After measuring 0.3g of each extract on a weighing machine, and measuring 1 ml of alcohol using a measuring cylinder, both the substance was then placed in a test tube.
- The solution was whirled around to mix the alcohol with the plant extract. The mixture was then placed in a petri dish. Sterile paper disc was then placed in the solution to soak up the plant extract. It was then left to dry.
- After all the plant extract has been prepared, it was then placed on the prepared agar plates accordingly. This procedure has to be done close with a source of flame as the petri dishes needs to be opened.
Results
Table 1 : The area of inhibition zone by various type of plant
Precautionary steps
1) Wear rubber glove while removing the plant fibre from water to prevent bacterial infection because there are a lot of microorganism in the plant fibre as the pumpkin stem has undergone retting. Wash your hands after handling the soaked fibre.
2) Wear lab coat and a pair of suitable shoes to protect the skin from any harmful or irritating substances and spillages.
4) The scalpel should be handled with care because it might cut yourself.
5) Tie back loose hair, roll back and secure your sleeves. Hair and clothing can get in the way while trying to work in lab. It is also dangerous and can cause spills or even potentially harmed yourself.
6) Hands need to be thoroughly washed before and after performing the experiment. This is to avoid ourselves from getting infected from any of the microorganism.
7) Most of the procedures need to be done in the laminar flow chamber where air is constantly being replaced. Thus, avoiding any contamination by any microorganism present in the air.
8) Since only bare hands were used in handling the bacteria, thus it is important to maintain a minimal contact, such as using only the last finger in opening the bijou bottle, with most of the materials and it is advisable to work closely with a source of fire, so that the materials remains sterile.
Discussion
Analysis of data and result
The results shown above are the clear area surrounding the paper disc including the paper disc which has been soaked with the ingredients as well. This data will be analyzed according to each specific bacterium.
For the first bacteria, E. coli the results obtained are 0.6362 cm2 for ginger, 0.5027 cm2 for cinnamon 0.3848 cm2 for mint and 0.6362 cm2 for garlic. From here, we can say that ginger and garlic has the highest inhibition area. Thus it can be concluded that these plants have the highest antimicrobial properties. This was followed by cinnamon whereas plant with the weakest antimicrobial property is mint. Whereas B. subtilis also showed quite similar pattern. From the average values table, it can be seen that garlic has the highest area of antimicrobial action with an area of cm². This is then followed by the garlic with an area of 0.9792 cm². Lemongrass and mint ingredient have almost quite close values of area of inhibition, where it is 0.3167 cm² and 0.3521 cm² respectively. It can be observed from the results from Table 1 and 3, for garlic, the difference between the two values differs greatly where the results are 0.2827 cm² and 2.2700 cm². Thus, this affects the calculation of the total average area of inhibition. This difference in values could again be due to handling of the materials during preparation. It has to be accepted that all the three results came from three different groups with different way of handling each materials. Overall, the antimicrobial activity of the plants towards B. subtilis goes with the following order,
Cinnamon > Garlic > Mint > Lemongrass
Staphylococcus aureus seems to be behaving quite differently from the other bacteria in the sense that its response towards the antimicrobial activity of garlic is much lesser than cinnamon, where the difference is astonishingly quite large, 1.4325 cm² (1.782 cm² and 0.3492 cm² for cinnamon and garlic respectively). Even mint, which is hypothesized to have a lower degree of microbial activity had a bigger area of inhibition compared to garlic and lemongrass which is 0.4294 cm². Out of all the figures, the area of inhibition of S. aureus bacteria by cinnamon is by-far the highest which is 1.782 cm². Generally, the order of plant having the highest to the lowest antimicrobial activity towards S. aureus is
Cinnamon > Mint > Garlic > Lemongrass
DISCUSSION
From the results obtained, it can be generally said that some does not truly correlate with the hypothesis. According to the hypothesis, the order of plant having the highest antimicrobial activity to the lowest is as follows,
Garlic > Cinnamon > Lemongrass > Mint
Out of the three bacteria, only E. coli seemed to correlate almost close to the expected result in the sense that garlic showed the highest antimicrobial action towards it. For the other two bacteria, cinnamon takes the lead. Mint even showed a higher antimicrobial property compared to garlic when placed in S. aureus agar plate. This is most likely due to some limitations during the preparation of the plant extract. It can be seen that during the preparation of garlic, it doesn’t seem to mix well with the alcohol. Although it has been pounded, some of the extract may be lost during transfer, and when mixing it with the vortex machine, the garlic seems to be clumping together. This might overall affect the concentration of garlic in the alcohol. The second possible explanation is the antimicrobial property of garlic is too weak to fight of the S. aureus bacteria. If this bacterium is said to be able to be transferred through breastfeeding, then for sure the degree of resistance of this bacteria is high. S. aureus is also a methicillin-resistant bacterium. Thus, garlic could contain chemicals that are easily fought off by S. aureus. On the other hand, it seems to be less resistance towards the antimicrobial property of cinnamon, giving the highest are of inhibition of bacterial growth which is 1.782 cm².
“Garlic's antibiotic properties have been more extensively studied than some of its other reputed health benefits. Louis Pasteur examined garlic's use as an antibacterial back in the nineteenth century and showed how it killed bacteria under laboratory conditions. Numerous modern studies confirm that garlic has definite antibiotic properties and is effective against many bacteria, fungi and viruses. According to Wright State University, garlic is approximately one per cent as potent an antibiotic as penicillin.”
(taken from Mendham T. at )
Lemongrass also seems to show a weak antimicrobial property in this experiment. One of the possibilities for this is that the lemongrass is prepared by blending it, and then it was left in open air for some time. This could be the reason for the low antimicrobial property in lemongrass. Most of the antimicrobial activity consists of enzymes which are enzymes and proteins which are easily denatured by mechanical actions and oxidations. Overall, lemongrass seems to show consistency in the measurement of the area of bacterial inhibition.
Limitations and Improvements
The plant extract might not be well mixed with the alcohol solution. Thus we should use a vortex machine to mix the compound thoroughly for about 10 minutes. This will ensure that the plant extract truly dissolve in the alcohol.
Further investigation
The antimicrobial properties of plant which have been exposed to different abiotic factors can also be investigated. For instance the plants which have been exposed to the sun and which have not can be tested. The plant extract from each plant is taken and tested. The procedure would be the same as the experiment above. The area of the inhibition zone of each plant is measured and calculated. The plant with the biggest area of inhibition zone is concluded to be the one that has the highest antimicrobial property.
Conclusion
The hypothesis is accepted. The bigger the area of the plan
