Transcript Locating and Evaluating Novel Antimicrobial Compounds in

Antibiotics in Your
Backyard:
Locating Antimicrobial Plants in
Our Environment
Our Project
We tested many plants in our environment in order
to locate these important antimicrobial compounds.
What We Were
Looking For

Antibacterial compounds that kill or
inhibit the growth of prokaryotic cells.

Pesticidal compounds that kill organisms
in the phylum annelidia, such as worms,
and arthropodia, such as insects.
Gram Positive Bacteria
Bacteria are classified as either Gram
positive or Gram negative based on
different structural characteristics
Gram positive
bacteria have cell
walls made mostly
of peptidoglycan
Gram Negative Bacteria
Gram negative
bacteria have
lipopolysaccharides,
lipoprotiens and
other
macromolecules
surrounding their
peptidoglycan cell
walls.
Pediococcus and E.coli
Bacteria Bioassay
Detects
antibacterial
compounds that
kill or inhibit the
growth of Gram
positive bacteria
and Gram negative
bacteria
Pediococcus is
gram positive
E.coli is gram
negative
Yeast Bioassay
Detects antifungal compounds that
kill or inhibit the growth of fungi.
Bioassay Plates


Used to locate antibacterial and antifungal compounds
Contain media (food) for a certain bacteria or fungus to
grow
Samples of plants we hope will inhibit the growth
of the microorganism are placed on hole punched
filter paper.
A Bioassay Plate
Extractions
Hexane and ethanol
extractions
Oils partition into non
polar hexane
Proteins and sugars
partition into polar
ethanol
Brine Shrimp Bioassay
Detects
naturally
occurring
pesticides in
plants
If a compound
kills brine
shrimp, it is
likely to act as a
pesticide and
kill insects, and
other pests
Brine Shrimp Bioassay
We would have added
plant extracts into
petri dishes
containing live brine
shrimp.
If the brine shrimp
were dead the next
day, we would have
concluded that the
plant contained
pesticidal compounds
Results
What We Found
Bioassay Results
We tested for antimicrobial compounds in plants in the
environment.
The ethanol extraction of garlic killed yeast. Therefore, its
proteins and sugars are antifungal.
Due to massive mentor error, we were unable to test St.
John’s Wort flower successfully. If the experiment had gone
as planned, its proteins and sugars would have show
antibacterial properties.
One of our plants provided an odd substance that grew in
media without bacteria. We tested it again and found that it
killed Pediococcus bacteria, suggesting it is antibacterial. This
substance was found in the ethanol layer extraction, meaning
it is in the proteins and sugars of the plant.
What’s Next?
New antibiotics
Various pharmaceuticals
Food preservation
Industrial applications
Safe and natural pesticides
Conclusion
This week, we randomly tested numerous
plants located around the OSU campus. We
found that the garlic killed the fungi and that
the mysterious leaf (substance) killed
Pediococcus.
There really are antibiotics
in your own backyard. So
save the environment.
Acknowledgements
Rachel McKenna, Mentor, Bioengineering, high
school
Lili Chu, Mentor, Bioengineering, Oregon State
University
Dr. Michelle Bothwell, Bioengineering, Oregon
State University