Fed-Batch Fermentation for PHA ProductionTeam Members: Andrew Bell, Amanda Dowling, Meagan Schrader, Daniela Valencia

Faculty Advisor: Dr. Kastner

Background Process Flow Diagram

Results

Sponsor/Client: Dr. Kastner

PurposeThe objective is to produce medium-chain-length PHA (mcl-PHA) at a scale that is able to compete with a portion of the plastic market, about 14,000 tons. The process involves culturing a strain of Pseudomonas putida, a researched bacterium that achieves high cell density and a large PHA yield, fed-batch fermentation, and a downstream process to remove the PHA from the cells. The PHA produced may be used as an alternative to standard plastics in hopes of decreasing the pollution in the environment.

Plastic pollution is accumulating from the waste of single-use plastics. There is currently 150 million tons of plastic in the oceans and most of it will never degrade. Polyhydroxyalkanoates (PHA) is a biodegradable material produced by a variety of bacterial strains found in the environment. PHA can be used to produce an alternative for plastic products, such as cutlery, plates, cups, and general containers.

Process Description○ A single plate of Pseudomonas putida

KTMQ01 is cultured until the required inoculation volume is obtained.

○ A 300,000 L fermenter is inoculated and the cells continue to grow.

○ Under nitrogen limitation, the cells produce PHA.

○ The PHA is extracted from the cells through downstream processes of centrifugation, acetone washing, and filtration.

○ The PHA is purified with a methanol-ethanol solution.

○ Vacuum drying produces pure, dry, mcl-PHA ready to be used for biodegradable plastic applications.

○ One complete operation takes 132 hours to produce 10.84 tons of PHA.

○ The process can produce 715.2 tons per year.

○ Theoretically, 20 operational lines of this process is required to produce approximately 14,000 tons of mcl-PHA annually.

○ This product can be used as a replacement for a significant portion of the petrochemical plastic market.