| Background
Your project will be associated with one of four companies:
Qualitas
Historically, most antibacterials were used in hospitals, where
they were incorporated into soaps and surgical clothes to limit
the spread of infections. More recently, however, those substances
(including triclocarbon, triclosan and such quaternary ammonium
compounds as benzalkonium chloride) have been mixed into soaps,
lotions and dishwashing detergents meant for general consumers.
They have also been impregnated into such items as toys, high chairs,
mattress pads and cutting boards. There is no evidence that the
addition of antibacterials to such household products wards off
infection. What is clear, however, is that the proliferation of
products containing them raises public health concerns. The potential
overuse of antibacterials in the home is troubling on other grounds
as well. Bacterial genes that confer resistance to antibacterials
are sometimes carried on plasmids (circles of DNA) that also bear
antibiotic-resistance genes. Hence, by promoting the growth of bacteria
bearing such plasmids, antibacterials may actually foster double
resistance—to antibiotics as well as antibacterials. (5)
Questions:
-Does triethylene glycol (Oust, Ozium) kill bacteria and fungi?
-Are there airborne bacteria and fungi to kill?
-Do bacteria develop resistance to triclosan?
-Does Microban kill bacteria when impregnated into clothes, toys,
and kitchen utensils?
La’au
The use of higher plants in the treatment of disease is as old as
the art of healing itself. Isaiah of Biblical times suggested that
a plaster of figs be placed on boils as a treatment of this form
of infection. The Chinese have used plants and herbs for centuries
in the treatment of many diseases. Thousands of phytochemicals have
been isolated and several serve as plant defenses against microbial
infection (3). Preliminary studies showed that plants have antibacterial
properties but these studies were done over 60 years ago (2). The
idea of using plants was abandoned with the discovery of antibiotics
from soil bacteria. However, the recent rise in antibiotic resistant
bacteria makes it imperative that new antibiotics are found. Additionally,
the rise in foodborne infections has prompted renewed interest in
the use of alternative natural microbial inhibitors (4).Possible
test plants:
Questions:
-Effects on growth of sublethal concentration(s) of an extract.
-Determine the Minimal inhibitory concentration (MIC) and/or minimal
lethal concentration (MLC) of an extract.
-The presence of lysozyme against gram-positive cells. Gram-negative
cells.
-Presence of antimicrobial peptides.
-What is your control?
PharMar
There is a high rate of rediscovery of antibiotic compounds in terrestrial
sources, which means the rate of novel compound discovery has been
going down. The sea’s potential as a resource is largely untapped.
So far, there are only four marine-based drugs on the market and
about 40 in clinical/preclinical development. A major therapeutic
area for marine natural products is infection. Novel antimicrobial
peptides (AMPs) have been isolated from the blood of the spider
crab Hyas araneus and the green sea urchin Strongylocentrotus
droebachiensis (1). The widespread resistance of bacterial
pathogens to conventional antibiotics has prompted renewed interest
in the use of alternative natural microbial inhibitors such as AMPs.
AMPs, termed bacteriocins, are ribosomally synthesised polypeptides,
which have bactericidal or bacteriostatic effect. A variety of antimicrobial
peptides have been discovered in recent years including defensins,
found in human skin, magainin, found in frog skin, and squalamine,
from the spiny dogfish shark.
Questions:
-Effects on growth of sublethal concentration(s) of an extract
of red or brown algae.
-Determine the Minimal inhibitory concentration (MIC) and/or minimal
lethal concentration (MLC) of an extract.
Gaia
The Gaia hypothesis proposes that living and nonliving
parts of the earth are viewed as a complex interacting system. Named
after the Greek earth goddess, this hypothesis proposes that all
living things have a regulatory effect on the Earth's environment
that promotes life overall.
Questions:
-What was the effect of the Cosco Busan oil spill on oil-degrading
bacteria on S.F. Bay beaches? (See lab exercise
22)
-Lichens are an important part of the ecosystem. How do the lichen
populations differ between stands of coyote brush and Eucalyptus?
-Evaluate indoor air quality in
Pacific Heights, after painting.
-Determine whether companion animals are a source of antibiotic-resistant
bacteria.
| Purpose
Working in groups of two students, you will
1. Answer the following questions in the background:
-What will you be looking for?
-Why is this important?
2. What will you look for with your experiments?
-How many trials will you do?
3. Discuss the significance of your results
4. Write your report in the proper
format.
Hypotheses
State your hypothesis
(& alternative hypotheses)
Materials Available
You must turn in the Supply Request
form before you begin working.
Cultures available:
Escherichia coli
Micrococcus luteus
Salmonella enterica
Shigella sonnei
Staphylococcus aureus
Saccharomyces cerevisiae
Pseudomonas aeruginosa
Streptococcus pneumoniae
Streptococcus pyogenes
Streptococcus mutans
Procedures at Qualitas, La'au
and PharMar
• Sample preparation. Prepare an extract by grinding
the appropriate tissue in a few milliliters of solvent in
a mortar and pestle. Possible solvents are sterile water;
methyl alcohol, ethyl alcohol, or acetone.
• Screening
• Serial dilutions
* MIC
• Lysozyme
* Bacteriocins
(AMPs)
• Isolating active compounds
• Bacterial numbers
• Population growth
|
Results
Displaying data
Discussion & Conclusions
Literature Cited
You are encouraged to read all the available information on
the topic for your paper. To select appropriate references,
you must evaluate your sources of information. Print and electronic
encyclopedias are often good to get familiar with a topic:
however, these are not appropriate references for a research
paper. The most reliable information is that published in
peer-reviewed journals. Peer-reviewed means that the author's
work has been read and accepted by colleagues in his/her discipline.
Start your literature search with Highwire, PubMed, or another
science database and search on your topic. Read the abstracts
and keep a list of interesting articles. Note, you must read
and cite the articles. Highwire, PubMed, and other databases
are not citations; these are indexes to articles.
1. Aldridge, S. “Marine Bioprospecting for Novel Drug.”
Genetic Engineering News 26(21):00-00, Dec 1 2006.
2. Carlson, J. J., H. G. Douglas, and J. Robertson. 1948.
“Antibacterial substances separated from plants.”
Journal of Bacteriology 55(2):241-248.
3. Cowan, M. M. 1999. “Plant Products as Antimicrobial
Agents.” Clinical Microbiology Reviews 12(4);
564-582. pdf
4.Friedman M, Henika PR, Levin CE, Mandrell RE. 2004 “Antibacterial
activities of plant essential oils and their components against
Escherichia coli O157:H7 and Salmonella enterica
in apple juice.” Journal of Agricultural Food Chemistry
52(19):6042-6048.
5. Levy, S. R. "The challenge of antibiotic resistance."
Scientific American March 1998 pp. 48-53. |
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