By Nikki Buck and
Mentors: Danielle Leiske and Alia Mulder
To compare the effectiveness of antimicrobial proteins
and other inhibiting bacterial growth on biomedical
What is bioengineering?
Applies engineering approaches to problems dealing
with biological systems.
How does this apply to life?
Bacteria grows on tracheal tubes.
Antimicrobial coatings are needed to prevent
Equipment and Materials
A gelatin compound used to stimulate the growth of bacteria.
A gram positive bacteria grown in MRS agar.
A gram negative bacteria found naturally in the human body that causes
A tool used to measure the thickness of a solid.
Process of disinfecting a surface.
Stir Plates/ Stir Bars
A machine that uses magnets to stir a solution.
A medical tube used in hospitals to clean out the air passageways of the
A machine used for sterilization.
Bacterial with thicker cell walls.
Bacteria with thinner cell walls.
Make plates of MRS and McConkey Agar
Cut equal sized pieces of sterile tracheal tubing
Soak pieces of tubing in antimicrobial solutions
Rinse tubing in phosphate buffer
Place tubing in agar plates
Incubate the plates overnight
Measure and record the diameter of kill zones
around each piece of tubing
Repeat previous steps but air-dry tracheal tubing
after rinsing in phosphate buffer
SDS- has a negatively charged head, hydrophobic tail. It is a
DTAB- Has a hydrophobic tail and a hydrophilic head
Nisin- a natural antimicrobial agent used as a lantibacterial
Lysozyme- causes hydrolysis of bacterial cell walls, fights
against bacterial infections
Albumin- Protein manufactured by liver, helps fluid remain in
the blood stream
Phosphate Buffer- a salt or ester of phosphoric acid (a
colorless liquid used in pharmaceuticals) that minimizes change
in the acidity of a solution when an acid or base is added
DTAB and Nisin worked best when killing pediococcus, a gram
Only high concentration DTAB, and low concentration lysozyme,
killed E. Coli
Low concentration was more effective
The wet tubing killed more bacteria than the dry
The SDS high and DTAB low concentrations showed a larger kill
zone for the dry tubing than the wet
Albumen did not bond with gram positive bacteria
Works well when it does
Our second trial had better results
Tubing was fully sterilized
Phosphate buffer was used as a control so it did not kill bacteria.
To our mentors, Alia Mulder, Danielle
Leiske, and David Pulitzer for
teaching us the concepts used in our
To Dr. Skip Rochefort for leading
us in this great learning adventure
that will change us forever, we will
never forget you!