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Summer 2018
Antimicrobial Peptides: the new solution to antibiotic-resistance
Restrictions on antibiotic use
coming December 1st 2018
Antimicrobial Peptides (AMP)
are a growing area in research
Synthetic AMP show promising
activity against bacteria
Challenges with AMP lie in
their stability inside the body
Longer stability results in
longer antimicrobial action
New regulations over the use of Medically Important
Antimicrobials in livestock are coming December 2018.
Reduced access to antibiotics leaves producer's livestock
vulnerable to outbreaks of bacterial infections. Antimicrobial
Peptides (AMP) are potential alternatives to antibiotic use.
AMP function differently from antibiotics, meaning bacteria
have a reduced likelihood of developing resistance. This
make AMP attractive candidates for feed additives and
treatments for bacterial infections.
While effective, natural AMP pose two main challenges: poor
stability when tested in physiological conditions; and complex
structure leading to expensive production. These challenges
can be overcome through the design of synthetic AMP. Four
synthetically designed peptides where tested to observe their
antimicrobial activity against two strains of bacteria under
physiological conditions. Potential recombinant production of
the AMP in yeast cells was also studied.
1) All AMP tested showed strong antimicrobial activity at
small concentrations
2) Of the AMP tested, two maintained stability for up to 7
hours in 25% serum
3) The two most stable AMP have potential for recombinant
production in yeast
Dr. Julang Li
Summer 2018
Figure 1) An example of the antimicrobial activity against bacterial colony growths for various
concentrations of the synthetic AMP tested, Syn-GNU7. For this trial, no bacterial growth was possible
when incubated with 2ug/mL of Syn-GNU7.
The image shows a row of 7 petri dishes, labeled corresponding to the concentration of AMP tested to
each plate of bacteria. The first petri dish on the left, contains no AMP and is labeled the Negative
Control. Going from left to right, as the concentration of AMP on each plate increases, the amount of
bacterial colonies growing decreases. The concentrations of AMP on each petri dish are as follows: Nc
(for Negative Control), 0.1, 0.5, 1, 2, and 4 micro-grams per milliliter.
1) Each peptide was tested against Escherichia coli and Methicillin-resistant Staphylococcus aureus in
concentrations ranging from 0.1ug/mL to 4ug/mL.
2) Peptide stability was assessed based on whether the peptide maintained antimicrobial activity against
E. coli after hours of incubation in 25% pig serum at concentration of 20mg/mL.
3) Peptides showing promising stability were incubated with a colony of yeast cells for up to 48 hours at
concentrations ranging from 100ug/mL to 600ug/mL.
Anna Maystrenko, Erin Miehe, Jenna Penney PhD, Julang Li PhD.
Department of Animal Biosciences, University of Guelph.
This research is supported by OMAFRA, and the University of Foshan.
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