Date of Award
Master of Science (MS)
Electrical and Computer Engineering (Holcomb Dept. of)
Dr. Richard Groﬀ, Committee Chair
Dr. Sarah Harcum
Dr. Adam Hoover
In the last three decades, biopharmaceuticals such as human growth hormone have been used to treat many diseases from HIV/AIDS to diﬀerent types of cancer. Controlling the growth of recombinant cells, such as Escherichia coli (E. coli), is essential for productivity and eﬃciency of biopharmaceutical manufacturing. The cell growth can be controlled by regulating feed rate as the limiting factor. Hence, a robust and eﬃcient feed controller – that only uses common industrial sensors – is desired. In this thesis, a controller is presented which can set the appropriate feed rate based on the metabolic state of E. coli. A robust metabolic state detector is designed which can detect whether the cells are in oxidative or overﬂow metabolism. And the controller periodically adjusts the feed rate based on the response of the cells. The controller, named BOOM II, maintains the cells close to the boundary of oxidative and overﬂow (BOOM) metabolism. Speciﬁcally, during a probe interval, the metabolic state detector exponentially increases the feed rate to the bioreactor. Then, by inspecting the real-time estimated oxygen uptake rate (OUR), the metabolic state is evaluated as oxidative if the sensitivity ratio (SR) signal passes a threshold, otherwise the metabolic state is considered to be in overﬂow. The performance of the BOOM II controller was validated by several fermen-tations and benchmarked against a robust and industrially tested controller that uses an exponential feed controller. Experiments that used the BOOM II controller re-sulted in higher cell densities, lower waste product levels and utilized less glucose than the parallel fermentation, using the exponential feed controller. The controller also detected metabolic changes to the culture due to growth phase shifts and re-combinant protein induction and adjusted the feed rate due to these disturbances. Since the BOOM II controller is based on metabolism fundamental concepts, it has the potential to work on diﬀerent strains of E. coli, other bacteria, yeast and possibly mammalian cells.
Lashkari, Shahin Gharakozlou, "Controlling Recombinant Escherichia coli Cultures to the Boundary of Oxidative and Overflow Metabolism (BOOM) for Robust Efficient Growth" (2017). All Theses. 2752.