•Traditional Polymers

•What are Biopolymers?

•How Biopolymers are Synthesized

•Environmental Benefits

•The Future of Biopolymers

Polystyrene: Coffee cups, Fast-food

Polyethylene:

HDPE: Milk containers

LDPE: Plastic bags, Packaging

Polyvinyl chloride: Piping, Meat wrap

Polyethylene terephthalate: Soda bottles

•Production of 1 pound of polystyrene requires 2.26 pounds of oil.

•1 lb provides the carbon monomers and the remaining 1.26 lbs of oil are burned to produce the electrical power to run the reaction.

•Organic solvent: 1,2-dichloroethane (~$30 per liter)

•Reaction Initiator: boron trifluoride with water (~$20 per gram)

• Oil use: 100 billion pounds of plastics are produced in North America annually

• Only 3% of these plastics are recycled

• Barely 25% of all soda bottles are recycled

• Energy storage for bacteria

• Physical properties of polyethylene, polystyrene, and synthetic polyesters

• Polyhydroxyalkanoates

HC CH2O C

CH3 O

Polyhydroxybutyrate Polyhydroxyvalerate

HC CH2O C

CH2 O

CH3

• Anaerobic Anaerobic EnvironmentEnvironment

• Abundant carbon Abundant carbon sourcesource

• 3-hydroxyacyl-CoA 3-hydroxyacyl-CoA polymerizationpolymerization

HC CH2O C

CH3 O

HC CH2O C

CH2 O

CH3

• A carbon source (corn) is ground into a mash A carbon source (corn) is ground into a mash and ‘fed’ to PHA-forming bacteriaand ‘fed’ to PHA-forming bacteria

• Glucose is extracted as the microbes ferment Glucose is extracted as the microbes ferment the mash and store the energy as PHA’sthe mash and store the energy as PHA’s

• The cells are washed and lysedThe cells are washed and lysed

•The PHA’s are separated by centrifuge and The PHA’s are separated by centrifuge and washed againwashed again

30% PHA by dry weight30% PHA by dry weight

3x higher than petroleum-based plastics

– High start-up costs

– Labor intensive processing

– High energy demands

Good• Ocean pollution would

decrease• Landfill space would

decrease (anaerob.)• Recycling costs could

be saved

Bad• Air pollution would

increase significantly• 2.39 pounds of fossil

fuel are burned for each pound of PHA produced

=o)

=o(

With greater financial and environmental costs, how will renewable biodegradable polymers take a hold in industry and with consumers?

• Mustard and alfalfa– Restriction Endonuclease gene

insertion– Use carbon-dioxide as carbon

source– 14% PHA by dry weight– Cheaper processing

[1] T. Gerngross. “Plastic from plants called costly” New Orleans ACS meeting. August 25, 1999

[2] C. Nawrath et al. Targeting of the polyhydroxybutyrate biosynthetic pathway to the plastids of Arabidopsis thaliana results in high levels of polymer accumulation. Proc. Natl. Acad. Sci. U.S.A., 12760, 1994.

[3] Yong Jia et al. Mechanistic Studies on Class I Polyhydroxybutyrate (PHB) Synthase from Ralstonia eutropha: Class I and III Synthases Share a Similar Catalytic Mechanism. Biochemistry, 1011 -1019, 2001.

[4] Shiming Zhang et al. Mechanism of the Polymerization Reaction Initiated and Catalyzed by the Polyhydroxybutyrate Synthase of Ralstonia eutropha. Biomacromolecules, 504 -509, 2003.

[5] Si Jae Park et al. Production of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) by Metabolically Engineered Escherichia coli Strains. Biomacromolecules, 248 -254, 2001.

[6] Lin Su et al. Enzymatic Polymerization of (R )-3- Hydroxyalkanoates by Bacterial Polymerase. Macromolecules, 229 -231, 2000.