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THE Phytastic PROBIOTIC
INCREASING THE BIOAVAILABILITY OF IRON IN THE
DIGESTIVE SYSTEM
Northwestern University iGEM 2012
The Northwestern 2012 iGEM Team
THE Phytastic PROBIOTIC
1. The Problem: Iron Deficiency
2. The Solution: Phytase
3. The Implementation
1. Producing Phytase
2. Delivering Phytase
4. The Model
5. The Ethics
6. The Conclusion
Over 2 Billion People Live with Iron Deficiency
That’s 30% Of the World’s Population
The Problem: Iron Deficiency
The Problem: Iron Deficiency
Iron deficiency
has worldwide
prevalence
among all
populations
The Symptoms of Iron Deficiency
Iron-Deficiency Anemia
Extreme Fatigue
Shortness of Breath
Impaired Immune
System
Impaired Mental
Function
Eventually Death
A Cause: Phytic Acid
Iron is usually present
in diet, but it is not
readily available for
absorption.
The iron that is found
in certain plants (such
as nuts, grains, and
bran) is chelated by
phytic acid.
Our Mission Statement
To create an inexpensive and
convenient system that increases
the bioavailability of iron in vivo.
THE Phytastic PROBIOTIC
1. The Problem: Iron Deficiency
2. The Solution: Phytase
3. The Implementation
1. Producing Phytase
2. Delivering Phytase
4. The Model
5. The Ethics
6. The Conclusion
The Solution: Phytase
Phytase: an enzyme that breaks down phytic acid.
Cleaves phosphate groups from phytic acid,
unbinding iron (and other nutrients)!
Delivering Phytase
Develop a probiotic that
will release phytase.
Fermented milk products
native to African and South
Asian diets.
These areas have a high
concentration of people
with iron deficiency.
THE Phytastic PROBIOTIC
1. The Problem: Iron Deficiency
2. The Solution: Phytase
3. The Implementation
1. Producing Phytase
2. Delivering Phytase
4. The Model
5. The Ethics
6. The Conclusion
Producing Phytase: Design
Successfully isolated phytase from Aspergillus niger,
Bacillus subtilis, Citrobacter braakii, and Escherichia
coli.
Placed with two strong constitutive promoters from
the Registry.
Producing Phytase: Assay
THE Phytastic PROBIOTIC
1. The Problem: Iron Deficiency
2. The Solution: Phytase
3. The Implementation
1. Producing Phytase
2. Delivering Phytase
4. The Model
5. The Ethics
6. The Conclusion
Delivering Phytase: Design
In order to release phytase into the stomach, the
probiotic must lyse after ingestion.
Delivering Phytase: Design
Stomach has a high HCl content (low pH).
ClC antiporter exchanges external chloride ions for
internal protons, increasing concentration of
intracellular chloride ions.
Pgad promoter detects increased concentration of
intracellular chloride ions, activating lysis cassette.
Pgad/Lysis at pH7
Pgad/Lysis at pH2
Delivering Phytase: Alternate Part
Cloned and created a part that would produce
GFP instead of lysing.
Originally used for testing purposes.
Can also be used simply as a low-pH detection
system.
Limitations: requires extracellular chloride.
Referred to simply as “Pgad/GFP.”
Pgad/GFP at pH 7
Pgad/GFP at pH 2
THE Phytastic PROBIOTIC
1. The Problem: Iron Deficiency
2. The Solution: Phytase
3. The Implementation
1. Producing Phytase
2. Delivering Phytase
4. The Model
5. The Ethics
6. The Conclusion
Phytastic System Model
Goal: Address the issue of
Is the Phytastic system
plausible?
Model Design:
Simulate Phytastic cells
entering the stomach as a
system of ODEs.
ODE Model
Antiporter Component Pgad/GFP component
Model Results
Recovers quickly
Stabilizes to orig. pH.
Reasonable conditions.
Comparable to literature.
Slonczewksi, J. L., R. M. Macnab, J. R. Alger, and A. M. Castle. 1982. Effects of pH and repellent tactic stimuli on protein methylation levels in
Escherichia coli. J. Bacteriol. 152:384-399.
Model Results
Assess goal of plausibility:
Constraints:
HOLINS: The Protein Clocks of Bacteriophage Infections Ing-Nang Wang, David L. Smith, and Ry Young
Annual Review of Microbiology, Vol. 54: 799 -825
Human stomach empties in 4-5 hours
1000 lysis enzymes/cell
THE Phytastic PROBIOTIC
1. The Problem: Iron Deficiency
2. The Solution: Phytase
3. The Implementation
1. Producing Phytase
2. Delivering Phytase
4. The Model
5. The Ethics
6. The Conclusion
High School Outreach
Video Collaboration
The rest of the interview can be viewed on our wiki!
THE Phytastic PROBIOTIC
1. The Problem: Iron Deficiency
2. The Solution: Phytase
3. The Implementation
1. Producing Phytase
2. Delivering Phytase
4. The Model
5. The Ethics
6. The Conclusion
The Conclusion
Phytase system produces phytase within the
cell.
Releasing the phytase demonstrates significant
phytase activity.
pH-inducible system demonstrates strong
inducement of both GFP and lysing of cells
when introduced to a low-pH environment.
The Conclusion: Parts
Newly Isolated Obtained from Registry Obtained from 2011
CUHK team
Aspergillus Niger Phytase Constitutive
promoter/RBS/double
terminator
Pgad Promoter
Bacillus Subtilus Phytase Lysis cassette
Citrobakter Braakii Phytase
E. Coli Phytase
Clc-ec1 antiporter
31 parts designed and constructed.
10 parts fully characterized.
The Conclusion: Favorite Parts
BBa_K912025
Promoter/RBS+ C.
Braakii Phytase
BBa_K912034
pH Inducible GFP
System
BBa_K912033
pH Inducible Lysis
System
Acknowledgements
Special thanks to:
Department of Biological Sciences
Jewett Lab graduate students
2011 Hong Kong-CUHK team for taking time to send us
a part they characterized that was not in the Parts
Registry!
Thank You
Be Phytastic!