Date of Graduation


Document Type


Degree Name

Bachelor of Science in Chemical Engineering

Degree Level



Chemical Engineering


Beitle, Robert


Single celled eukaryotic organisms are advantageous in the production of proteins for use in biopharmaceuticals due to their ease of cultivation and manipulation. Because of high cell density during fermentation and an ability to allow post-translational protein modifications, yeast is particularly well-suited. To maximize the specific formation rate of the desired proteins, an optimum specific growth rate of the yeast should be found and maintained. This rate is dependent upon pH, temperature, dissolved oxygen content, and carbon feed rate. Fermentation can be done in a fed batch reactor system, and it is possible to use a Buglab (online biomss) sensor to monitor the conditions in the reactor. The focus of this project was to create a Proportional Integral Derivative Controller algorithm to optimize the specific growth rate of a yeast automatically. Using real time data provided by the online biomass sensor, the algorithm will be able to calculate an output to correct any deviations in the optimum growth rate by controlling the feed rate. Maintaining this specific growth rate will in turn optimize the production of heterologous proteins.


Bioreactor, PID Algorithm, Fermentation, Yeast, Eukaryote