oral defense bio

7/29/2019 Oral Defense Bio

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By Alec Bukuhan and Xandro Hizon of S2015


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Significance

We are testing Citronella grass because it is relativelycommon in the Philippines, as well as other parts of

the world, and it is already being commonly used in

things like insect repellant, scented candles and the

like, although it is not well known as an antibacterialagent. This is why we are testing this plant if

proven to have antibacterial qualities; it will be a

great, inexpensive, natural substitute for chemical

antibacterials or more expensive ones. Also, the

already well-established industry of citronella

products will make it easier for manufacturers to

begin making and producing it as an antibacterial.


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Objectives

To extract chemicals in citronella

To properly test the presence of antibacterial

properties

To compare the extract of citronella to alcoholin its effectiveness as an antibacterial agent

To carefully count the number of bacteria in

the agar plates


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Variable

Independent Variable

Presence of the extract of Citronella grass

Cymbopogon nardus

Dependent Variable Number of bacteria Staphylococcusaureus


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Problem

Declarative Form: The researchers

which to find out whether applying

Citronella grass extract to bacteria will

result in the reduction of the bacteriapresent, or in other words, test whether

Citronella grass extract exhibits

antibacterial properties. Question Form: Does Citronella grass

extract exhibit antibacterial properties?


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Hypothesis

If the extract is applied, then there

will be less bacteria present in the

end.


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Scope and Delimitations

The experiment will focus only on testingCitronella Grass or Cymbopogon nardus, andno other plant species. The researchers will usethe colony count test. We used the

Staphylococcus aureus bacteria since it isfound on surfaces and is commonly used to testdisinfectants Lastly, we are testing theCitronella grass extract on its antibacterialproperties, but more on its function as adisinfectant or antiseptic and not as anantibiotic, although these all technically fallunder antibacterial.


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Materials

ME-012 VORTEX MIXER (TYPE 37600)AND THE 0.5-5ML TRANSFERPETTE S

ME-043 CLYDE APAC BIOSAFETY CABINET CLASS II

Alchohol lamp

Incubator

Sterile Microbial Content Test Agar (a litre) Beakers for mixing

100mL capped bottles x8

Petri Dishes x30

Distilled water (1 litre)

Phosphate buffer (540mL)

Already diluted Staphylococcusaureus


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Procedure

1. First, the materials were prepared, including the bacteria cultureStaphylococcusaureusto be used for testing that was already diluted

to the 10^-4 and 10^-5 of the original culture. Note that these two

dilutions are to be used separately.

2. Next, the 10% citronella and the 1% citronella disinfectants were

made by mixing 10mL of the extract to 100mL of water and 1mL of the

extract to 100mL of water respectively. Also, Tween 80 was added to

make the citronella oil dilute.

3. Next, 1mL of the 10^-4 test inoculum was added to the 100mL of

disinfectant, was mixed well and left for 5 minutes. This was done for

both the 10% and 1% citronella disinfectants.

4. Next, 10mL out of the 100mL of the disinfectant with bacteria was putinto 90mL of a Phosphate buffer and mixed well. Again, this was done

for both percentages.

5. Finally, 1mL of that final concoction was plated, (5 plates for each

percentage) and agar was poured into the plates.


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6. Steps 3-5 were done again, except with

the 70% alchohol as a comparison.7. Steps 1-5 were done again, except with

the 10^-5 dilution.

8. The control was made by plating 1mL of

each dilution untreated and also coveredin agar.

9. The plates were incubated at 30-35degrees C for 1-2 days.

10. Once the time elapsed, the colonies werecounted and the results, recorded andcompared.


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Control Groups

Standard TNTC

TNTC

TNTC

TNTC

TNTC

(272,299)

(27,24)

(3,6) (2,0) (0,0)

Positive

Control

- - - (45,

38)

(5,3) - - - - -


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The Effects of the Presence of Citronella Extract to the

Number of Bacteria Staphylococcusaureus

Trial 1 2 3 4 5 Average

70%

Alcohol

0 0 0 0 0 0

1%Citronella

Extract

Solution

1 8 14 7 13 8.6

10%

CitronellaExtract

Solution

3 0 3 1 1 1.6


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The Effects of the Presence of Citronella Extract to the

Number of Bacteria Staphylococcusaureus

Trial 1 2 3 4 5 Average

70%

Alcohol

0 0 0 0 0 0

1%Citronella

Extract

Solution

4 1 2 2 2 2.2

10%

CitronellaExtract

Solution

1 0 0 0 0 0.2


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Analysis

Our data showed that the 1% Citronella Extract solution killsaround 58.64% of the bacteria while the 10% Citronella

Solution kills around 95.57%. This shows that the Citronella

extract does in fact possess some antibacterial properties, more

specifically, disinfecting properties since we used a typical

surface bacteria (Staphylococcus aureus) in our testing. Thismeans that Citronella extract has the potential of being used in

disinfectant products such as what we used is the control set-

up- alcohol. However, In our data, the dilution of 10^-5 yielded

less bacteria than we hoped and planned for, making the results

of that group less definitive, but still usable. The 10^-4 dilutiongroup yielded more bacteria and showed us more dependable

data.


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Conclusion

Citronella grass Cymbopogon nardusdemonstrates antibacterial properties.

It might be as effective as alcohol since

the solution is still only a 10%Citronella solution. In the data, The

10% solution almost killed everything

in both the 10-4

and 10-5

standards


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Recommendation

Include the exposure time of thebacteria to the disinfectant as a variable

Test more standards of dilution (the

10^-4 etc.) to get more definitiveresults

Test the Citronella extract against more

species of bacteria


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Use other methods of testing the extract

other than the colony-counting methodwe used.

Test other concentrations of the extract

in the disinfectant.


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Bibliography

http://ph.news.yahoo.com/blogs/the-inbox/citronella-grass-boon-farmers-environment-032659995.html

http://citronella-oil.blogspot.com/

http://www.news-medical.net/health/What-is-Staphylococcus-Aureus.aspx

http://www.foodsafety.gov/poisoning/cau

ses/bacteriaviruses/staphylococcus/index.html Hizon Laboratory
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