Volume 6, Spring 2008 - Saddleback College

Fall 2007 Biology 3A Abstracts
7. THE EFFECT OF TEMPERATURE ON BACTERIAL COLONY FORMATION IN Escherichia coli.
Anoush A. Garakani and Cassra Minai. Department of Biological Sciences, Saddleback College, Mission
Viejo, California 92692
Rapid bacterial growth is usually associated with warm temperatures. Although each species of
bacteria have their own optimal environments for growth, it is critical to learn about those bacteria which
can cause harm to humans. Escherichia coli is a very well known bacterium which has plagued the food
industry due to its rapid generation time. It is crucial to know which temperatures are able to inhibit the
growth of bacterial colonies in Escherichia coli in order to prevent sickness from food products both in
restaurants and at home. Temperature is known to have a significant effect on bacterial growth, and since
there is evidence that the optimal growth temperature for Escherichia coli is 37o C, it was predicted that
the least bacterial colony inhibition would be at 37o C and the greatest inhibition would be at eight
degrees centigrade. Means of colony formation for 37o C were (1655.5 ± 134.19, ± SEM), no colony
formation was found for those incubated at eight degrees. To verify the presence of the bacteria in the
eight degree plates, after complete inhibition was verified the eight degree plates were incubated at 37o C
for 24 hours (1364.8 ± 128.32, ± SEM) there was no significant difference 37o C incubation and those
incubated at 37o C after incubation at eight degrees (p > 0.05). These differences support the hypothesis
that Escherichia coli can be inhibited at very low temperatures and can be of great use in the food
preparation industry.
8. CYNIPIDAE GALL DISTRIBUTION ON YOUNGER AND OLDER COAST LIVE OAK TREES,
QUERCUS AGRIFOLIA. Brooke A. Hargis and Candice B. Archer. Departments of Chemistry and
Biological Sciences, Saddleback College, Mission Viejo, California 92692
The Gall Wasp (Hymenoptera, Cynipidae) induces the formation of plant galls. A gall is an
abnormal plant tissue growth formation that results from the plant reaction to a growth-regulating
chemical released by the wasp as it feeds on plant tissue. This newly formed gall serves as a safe
shelter and a food source for the gall wasp larvae to develop. The “Plant Vigor Hypothesis” states that
insect performance is better on faster-growing plants. Since younger trees have increased levels of
cellular mitosis and overall vitality when compared to older trees, we predicted that gall counts would be
higher among younger trees than among older trees. Galls were counted up to 2.13 meters above
ground on a total of 30 trees. Of these 30 trees, 15 had a circumference of 50 cm or less, thus
considered “younger”, and 15 had a circumference of 90 cm or more, thus considered “older”. The
average number of galls per tree was significantly greater on older (5.7 ± 4.6 s.d.) trees than on younger
(1.4 ± 0.74 s.d.) trees (p=1.2 x 10 -3 , one-tailed). Therefore, our results rejected the “Plant Vigor
Hypothesis”. Instead, they supported an alternative hypothesis for the preference pattern of gall wasps,
the “Plant Stress Hypothesis”. This hypothesis states that slower-growing plants contain more nitrogen
and thus favor insect performance. We discuss our results within the context of this hypothesis.
9. EXTRACTION OF IRON FROM BREAKFAST CEREALS. Claudia M. Shuldberg and Ximena M. Horne.
Department of Biological Sciences, Saddleback College, Mission Viejo, California 92692
Maintaining a nutritional diet is an important topic for every person’s health. Iron is a very important
component to the human body since it affects all the bodies’ functions. Iron can be found in different kinds of
food and it is advertised as a primary component on breakfast cereals. Since iron is a ferromagnetic element,
it can be extracted from Total Whole cereal and Kellogg’s Product 19 cereal using a Teflon covered magnet.
The iron extracted from both cereals was compared to test if both cereals have the same amount of iron per
serving size. Out of 10g of Total Whole cereal 0.00601g ± 0.000130g (±se) of iron was extracted and
0.00573g± 0.000130g (±se) of iron from Kellogg’s Product 19 cereal. A two‐tailed unpaired t‐test showed that
there is not a significant difference of iron when comparing the two cereals (p= 0.0806).
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Saddleback Journal of Biology
Spring 2008