Saddleback Journal of Biology - Saddleback College

Spring 2010 Biology 3B Paper
G ro w th In h ib itio n (m illimeters)
3.5
3
2.5
2
1.5
1
0.5
0
Lavender Rosemary Control
Figure 1. Average growth inhibition (mm) of E.coli
of the Lavender group was 2.45 ±
.546 (± S.E.M). The rosemary group was 2.91 ± .415
(± S.E.M) and the control group was 0.14 ± .070 (±
S.E.M).
Discussion
The average growth inhibition between the
Rosemary group and the control group was found to
be significant as was the growth inhibition between
the Lavender group and control group. This data
supports the hypothesis that these particular aromatic
plants significantly inhibit bacterial growth and
reflect similar results to the study of E coli. inhibition
by basil (Lopez et al., 2005).
No statistical difference was found in
growth inhibition between the Lavender and
Rosemary groups. This provides evidence for the
validity of the null hypothesis, that there is not a
significant difference in the E coli. growth inhibition
ability of these two plants. These results also appear
to run counter to a previous study which found that
variances in concentration of essential oils caused
significant differences in antibacterial activity
(Karamanoli et al., 2004). The differing results could
potentially have been caused by human error in this
Literature Cited
Blondel, J., Mennerat, A., Mirleau, P., Perret, P.
“Aromatic plants in nests of the blue tit Cyanistes
caeruleus protect chicks from bacteria.” Ocelologia
(October 2009): Vol. 161, Iss. 4; 849
Karamanoli, K., Vokou, D., Menkissoglu, U.,
Constantinidou, H.-I. “Bacterial Colonization of
Phyllosphere of Mediterranean Aromatic Plants”.
Journal of Chemical Ecology (2004): 2035-2048
Lopez, P., Sanchez, C., Battle, R., Nerin, C. “Solidand
vapor-phase antimicrobial activities of six
essential oils: suscepitibility of selected foodborne
study. Namely, chads may not have been uniformly
coated in their respective oils due to a density
difference amongst the two sample groups. If
Rosemary oil was more dense, upon being shaken to
remove excess, less may have dropped off then
would have for the Lavender chads. As a result, the
proportion of Rosemary oil for inhibition to Lavender
oil would not be equal skewing results in favor of the
Rosemary group . Also, while sterilizing the essential
oils, the Rosemary oil was found to come to its
boiling point faster then did the Lavender oil which
could have skewed the results. Seeing as how the
lavender was removed at first sign of boiling,
resulting in a shorter amount of time boiled, the
Rosemary oil could potentially have been more
sterile to begin and with less introduced bacteria
inaccurately appear to inhibit growth more.
This experiment looked at the effects of two
of these aromatic plants on a single strain of
bacteria’s growth. Lavender and Rosemary have an
inhibitory effect on bacterial growth primarily due to
their chemical composition. Rosemary is comprised
primarily of Rosemarinic acid, which is a natural
polyphenol antioxidant carboxylic acid that
has been shown to have antiviral and antibacterial
properties. (Triantaphyllou et al., 2001). Lavender is
composed primarily of Terpenes and Sesquiterpenes,
which as mentioned earlier possess strong
antibacterial abilities.
Further experiments could employ a wider
range of essential oils and a larger sample size to
better ascertain if/how these aromatic plants differ in
their effect on E coli. growth. In addition, a single
essential oil could be used and tested against a variety
of bacterial strains to see if the inhibitory effect is
widespread or limited to E coli.
bacterial and fungal strains.” J Agric Food Chem
(August 2005); 53(17):6939-46
Picagglia, R., Maroti, M., Giovanelli, E., Deans,
S.G., Eaglesham, E. “Antibacterial and antioxidant
properties of Mediterranean Aromatic Plants”.
Industrial Crops and Products (1993): Vol.2, Iss.1;
47-50
Svoboda, K., Hampson, J., “Bioactivity of essential
oils of selected temperate aromatic plants :
antibacterial, antioxidant, anti-inflammatory, and
other related pharmacological activities” Plant
biology Department, SAC Auchincruive, Ayr,
Scotland, UK., KA6 5HW
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Saddleback Journal of Biology
Spring 2010