GROWTH INHIBITION COMPARISON OF CINNAMOMUM SPECIES,
CINNAMOMUM ZEYLANICUM AND CINNAMOMUM CASSIA, ESSENTIAL OIL
EXTRACT AGAINST ESCHERICHIA COLI
Anna Flores, Christopher Mayorga
Department of Biological Sciences
Saddleback College, Mission Viejo, CA, 92692
Cinnamomum species are known for their pleasing aroma, distinguishable taste, and
medicinal qualities. Research studies progress the medicinal practicality of using
Cinnamomum species’ essential oils as an antimicrobial agent against pathogenic
microbes such as Escherichia coli and Staphylococcus species [Consider: Research
studies have suggested there is a medicinal use for species of Cinnamomum, specifically
their essential oils, as an antimicrobial agent. Such species of bacteria include pathogenic
Escherichia Coli and Staphylococcus]. A comparison of two Cinnamomum species,
Cinnamomum zeylanicum and Cinnamomum cassia was conducted to distinguish if there
would be a significance [grammatically: significant] difference between zone of
inhibitions against E. coli [Awkward phrasing – Consider: A comparison of two
Cinnamomum species, Cinnamomum zeylanicum and Cinnamomum cassia was analyzed
to discern the inhibitory zones of each on E. coli]. Based on previous research, the
experimental data should have a significant difference between the Cinnamomum species
[Consider: inhibitory zones between the Cinnamomum species should significantly
differ]. The disk diffusion method was implemented for the both experimental groups,
[Grammatically: A colon should be used when listing these categories] C. zeylanicum,
and C. cassia, and the control. Sterile paper disks were treated with 5 l of either
deionized water for control or essential oil from either C. zeylanicum or C. cassia for
experimental groups. Then agar plates were incubated at 37° Celsius for 48 hours. The
mean zone of inhibition diameter in mm [Consider: The diameters of the mean zones of
inhibition, in millimeters] for control, C. zeylanicum and C. cassia groups were 0.00 mm
± 0.00 (±SE, n=39), 18.3 mm ± 0.19 (±SE, n=39), 27.1 mm ± 0.31 (±SE, n=39)
respectively. An analysis of variance (ANOVA) and Bonferroni correction test were
conducted and [Consider adding here: it was] concluded that there was [Consider: is
instead of was] a shared significant difference between all groups (p<0.0001 ANOVA,
and Bonferroni correction).
Introduction
Cinnamomum species have been one of the many spices that have been researched for
its many health-benefiting properties. Essential oils in plants have been used in many
pharmaceutical therapies, alternative medicines, food preservation [Grammatically:
preservatives], and other natural therapies for thousands of years (Burt, 2007, Nuryastuti,
2009, Saraf, 2011, ). Recent studies show that Cinnamomum essential oils have
promising antimicrobial effects against antibiotic resistant bacteria such as Escherichia
coli and Staphylococcus species. E. coli, a Gram-negative bacteria found in commercial
food items such as raw meat and liquid juices [Redundant, the definition of a juice is that
it is liquid. Consider “juices and raw meats” such that it isn’t implied that the juice is
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raw.], is one of the main causes of food poisoning in humans. In some serious cases it
may lead to the destruction of red blood cells or other problematic situations [Consider:
Just using the term “problems”, or “negative effects on” .]in the liver or kidney. An
increasing number of antibiotic resistant bacteria in E. coli has brought many concerns to
consumers of such products [ Consider: Concerns with the increasing number of
antibiotic resistant strains of bacteria, specifically strains of E. coli, have been voiced by
the consuming public.] (Nuryastut, 2009, Rojas-Grau, 2007).
Cinnamaldehyde, an organic compound found in essential oils of Cinnamomum,
seems to have a major part in the antimicrobial properties [Consider: to be the major
antimicrobial property] of Cinnamomum species essential oils (Ciftci, 2010, El-Baroty,
2010, , Gende, 2008, Hoque, 2007, Nuryastuti, 2009, Rojas-Grau, 2010). It has been
found that E. coli is not able to develop resistance to the essential oils of many plant
species. Studies are showing that Cinnamomum essential oils have greater antimicrobial
activities against E. coli compared to other essential oils of thyme, lemon grass, clove,
etc. (Rojas-Grau el al. 2007). Two of the common species of Cinnamomum that are used
in antimicrobial studies are Cinnamomum zeylanicum and Cinnamomum cassia (Burt,
2007, Gende, 2008).
Since both species of cinnamon show promising results against bacteria, research
between the potency of the two species will be conducted to see if there will be any
statistical difference between the essential oil’s zones of inhibition on E. coli
Methods
Thirty-nine nutrient agar plates were prepared in a biology laboratory located at
Saddleback College. An even amount of agar (Hardy Diagnostics CRITERION™ Agar)
was poured into thirty-nine [Consider: “the aforementioned”] Petri dishes. Aseptic
techniques were used in order to prevent any accidental contamination, in which the rim
of the flask was sterilized by a Bunsen burner before and after each agar plate was made
[Consider: To prevent any accidental contamination, the rim of the agar flask was
sterilized by a Bunsen burner before and after each agar plate was made; a very common
aseptic technique].
Cultured Escherichia coli was provided by the Saddleback College Biology
Department. Test tubes containing E. coli were sterilized over the flame of a Bunsen
burner before and after obtaining the bacteria. The lawn-spread method was performed
on each agar plate. Gilson PIPETMAN® P-1000 pipettes were used to transfer 0.4 mL of
E. coli onto the agar plates. Glass spreaders were placed in an [Grammatically: a] 95%
ethanol [Do you mean they were placed in a 95% ethanol solution?] sterilized over a
flame, and were used to evenly distribute the bacteria onto the nutrient agar plate. The
thirty-nine Petri dishes were divided into three groups: the control group, Cinammomum
zeylanicum group, and Cinammomum cassia group. There were thirteen dishes for each
experimental group.
The disk diffusion method will be [Grammatically: was] used to measure the
antibacterial activity of the essential oils. One hundred and seventeen paper chads were
prepared and autoclaved for sterilization. Each experimental group had a total of thirty-
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nine disks per group and three chads per agar plate The chads were treated with solutions
and [Consider: “of”] oils prior to being placed on the agar plates. Oils and other fluids for
treating sterile paper disks transferred via Gilson PIPETMAN® P-20. The control group
was treated with 5 l of deionized water per chad and [Grammatically: “the chads were
placed”]were placed on each dish using sterilized tweezers. Five mL of both pure
essential oils (Frontier Natural Products Co-op, Aura Cacia 100% pure essential oils)
were[Consider: of each pure essential oil…was]( measured in a graduated cylinder, were
[Consider: was] boiled in a flask to be sterilized and then closed with a cork to prevent
any further contamination. The C. zeylanicum group was treated with 5 l of sterile C.
zeylanicum essential oil [per chad?]and also placed on each dish using sterilized
tweezers. The same procedure was performed again, but for the species C. cassia.
Once the chads were properly treated and situated in the agar, Petri dishes were
labeled with a wax pencil according to group and placed into one of the three metal
holders provided. They were then incubated at 37° Celsius for 48 hours. After 48 hours,
the cultures were removed from the incubator. Data were [Grammatically: was] then
collected and the diameters for the zone of inhibitions were measured in millimeters.
Results
The mean zone of inhibition for the control group containing deionized water and
E.coli, after 48 hours, was 0.00 mm ± 0.00 (±SE, n=39). After a 48-hour period, the
average zone of inhibition was 18.3 mm ± 0.19 (±SE, n=39) for C. zeylanicum
experimental group [This doesn’t seem necessary as the reader realizes that C.
zeylanicum is part of the experimental group] with E.coli. C. cassia experimental group
had an average zone of inhibition of 27.1 mm ± 0.31 (±SE, n=39) after the 48-hour
incubation period [Consider: After a 48-hour incubation period the C. cassia displayed an
average zone of inhibition of …].
An analysis of variance (ANOVA) was run on the measured diameters for zone of
inhibition [Consider: of the zones of inhibition]. The results of the ANOVA reported the
p-value to be less than 0.0001, indicating that there was a significant difference. A
Bonferroni correction test was conducted and indicated that there was a significant
difference between all the three groups supporting the ANOVA results.
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Figure 1. The zone of inhibitions of the control, C. zeylanicum, and C. cassia groups
after a 48-hour incubation period. There is a shared statistical difference between all three
groups (p<0.0001 ANOVA, and Bonferroni correction) [What do the error bars indicate?
I cannot actually see the graph, as the format on my computer will not allow me to, so I
am assuming they are there.]
Discussion
By examination of the experimental data, [Consider: “it was concluded that-“] there
was a shared significant difference between all three groups (p<0.0001 ANOVA, and
Bonferroni correction, Figure 1). The control group’s data indicated no detrimental
variables that maybe associated with bacteria or agar used for experiment [What does this
mean? Do you mean to say that statistically the water had no inhibitory effect on the
E.coli?]. Both C. zeylanicum and C. cassia experimental groups data contain a significant
difference therefore supporting the hypothesis of a significant difference between the
Cinammomum species [Consider: The data gathered between both experimental groups
displays a significant difference between the inhibitory zones of each species. This
supports the previous hypothesis](p<0.0001 ANOVA, and Bonferroni correction, Figure
1). Even though there has been many experiments on the antimicrobial effects of the
Cinammomum species, little research has been done in a direct comparison of C. cassia
and C. zeylanicum [Consider: Although experimentation on the antimicrobial effects of
Cinammomum has been previously performed, little research has compared specific
species of Cinnamomum such as C. cassia and C. zeylanicum]. Data from some past
separated [Grammatically: separate] experiments reported C. cassia essential oils
contained a larger zone of inhibitions [Grammatically Either: “a larger zone of inhibition”
or “larger zones of inhibition”] against E.coli than C. zeylanicum essential oil (Ciftci et
al. 2010, El-Baroty et al. 2010, Gende et al. 2008, Hoque et al. 2007, Lee & Ahn 1998,
Nuryastuti et al. 2009, Rojas-Grau el al. 2007, Saraf et al. 2011). Speculation that may
contribute to the results of the experiment would be the concentration of antimicrobial
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compounds in essential oils, such as trans-cinnamaldehyde [Consider: Factors that may
have contributed to the results include the possible difference in antimicrobial compound
concentration of the essential oils, such as trans-cinnamaldehyde] (El-Baroty et al. 2010,
Gende et al. 2008, Saraf et al. 2011). Also preparation of each essential oil might be a
major factor. For example, C. zeylanicum essential oils are mostly extracted from the
leaves of the plant compared to C. cassia which is usually prepared from the bark and
branches (Ciftci et al. 2010, Gende et al. 2008, Lee & Ahn 1998, Nuryastuti et al. 2009,
Rojas-Grau el al. 2007, Saraf et al. 2011). Further experimental research would be
necessary to evaluate any organic compound concentration differences between the two
Cinammomum species essential oils.
As studies of the Cinammomum genus continues, the health benefits seem to be
increasing. From anti-inflammatory to antimicrobial properties in most species the
benefits for human health has potential for further medical research (Burt, 2004, Ciftci et
al. 2010, Hoque et al. 2007, Lee & Ahn 1998, Rojas-Grau el al. 2007). Also the
increasing interest in use of natural antimicrobial additives to food products for
perseveres can lead to more research regarding the Cinammomum genus (Burt, 2004,
Gupta et al. 2008, Hoque et al. 2007). This experiment supports that C. cassia would be a
favored species for antimicrobial uses than C. zeylanicum.
Acknowledgements
We are sincerely grateful to Saddleback College Biology Department and Professor
Steve Teh for providing guidance, materials, and assistance that greatly assisted the
experiment.
Literature Cited
Burt, S. 2004. Essential oils: their antibacterial properties and potential applications in
foods - a review. International Journal of Food Microbiology 94:223-253.
Ciftci, M., Simsek, U. G., Yuce, A., Yilmaz, O., & Dalkilic, B. (2010). Effects of
Dietary Antibiotic and Cinnamon Oil Supplementation on Antioxidant Enzyme
Activities, Cholesterol Levels and Fatty Acid Compositions of Serum and Meat in
Broiler Chickens [Only the first word of this title should be capitalized]. Acta
Veterinaria Brno. University of Veterinary and Pharmaceutical Sciences LA English.
El-Baroty G.S., El-Baky A., Farag R.S., Saleh M. A. 2010. Characterization of
antioxidant and antimicrobial compounds of cinnamon and ginger essential oils.
African Journal of Biochemistry Research Vol. 4(6): pp. 167-174.
Gende L., Floris I., Fritz R., Eguaras M. J. (2008)- Antimicrobial activity of cinnamon
(Cinnamomum zeylanicum) essential oil and its main components against
Paenibacillus larvae from Argentine. Bulletin of Insectology, 61 (1): 1-4
Gupta C., Garg A.P., Kumari A., Uniyal R C. 2008.Comparative analysis of the
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antimicrobial activity of cinnamon oil and cinnamon extract on some food-bone
microbes. African Journal of Biochemistry Research Vol. 2(9): pp. 247-251.
Hoque M. D., Inatsu M. L., Juneja, Vijay and Kawamoto S. (2007) Antimicrobial
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Review Form
Department of Biological Sciences
Saddleback College, Mission Viejo, CA 92692
Author (s): Anna Flores, Christopher Mayorga
Title Growth inhibition comparison of Cinnamomum species, Cinnamomum
zeylanicum and Cinnamomum cassia, essential oil extract against Escherichia coli
Summary
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Summarize the paper succinctly and dispassionately. Do not criticize here, just show that you understood the
paper.
The differences in antimicrobial effects between two species of Cinnamomum were
analyzed in this experiment. E. coli was used to gauge this difference. Much research
had previously been done on the genus of Cinnamomum as a whole, but very little
experimentation had been done between the two separate species. Data from
separate experiments had been gathered and displayed a difference in antimicrobial
effects between the two species. Agar plates were made and each oil was applied to
small chads – water was used as a control. The diameter of the halo around the
chads (in the agar) would display the inhibitory zone of each essential oil as it would
inhibit the growth of E. coli around it. None was observed with water. A larger
diameter was observed for C. cassia than for C. zeylanicum. Further experimentation
could be done to discern a similarity or difference in concentration of antimicrobial
compounds in each Cinnamomum species. Difference in results may be due to the
processing of each cinnamomum species as one is gathered from the bark of the tree
and one is extracted from the leaves.
General Comments
Generally explain the paper’s strengths and weaknesses and whether they are serious, or important
to our current state of knowledge.
The only large weaknesses this paper had were grammar and problems with
awkward wording. Other than that the experimentation and ideas behind the
experiment were exceptional. The organization of the experiment decreased
unwanted variables and served to test the given hypothesis directly. As stated in the
discussion and introduction this venue of research is particularly important as
antibacterial resistant strains of E. coli have cropped up in raw meat supplies as well
as other food products, however E. coli has displayed it cannot modify its strain to
protect itself from essential oils. This could serve as a way to protect the consumer
public from outbreaks of E.coli.
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Technical Criticism
Review technical issues, organization and clarity. Provide a table of typographical errors,
grammatical errors, and minor textual problems. It's not the reviewer's job to copy Edit the paper,
mark the manuscript.
This paper was a final version
Recommendation
 This paper should be published as is
 This paper should be published with revision
 This paper should not be published
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This paper was a rough draft