(427f) Optimal Control of a Fed-Batch Bioreactor for Maximized Carotenoids Productivity

Authors: 
Raftery, J. P., Texas A&M University
Jaladi, T., Texas A&M University
Karim, M. N., Texas A&M University

Carotenes such as β-carotene have a positive impact in human health as a precursor of vitamin A. Structural complexity of these compounds makes their chemical synthesis a difficult endeavor, facilitating the need for their biological production. Fed-batch operation is commonly used in these processes to allow for increased cell viability through the mitigation of substrate and product inhibition, thereby increasing the productivity of the carotenoid product[1,2]. This work looks to examine the operating conditions necessary to achieve the highest productivity of the desired carotenoid products when produced via fed-batch operation. First, a two-level parameter estimation method is utilized to develop a reliable kinetic model for the batch production of carotenoids via fermentation to describe the glucose consumption, metabolic product formation and depletion, and the carotenoid production in the Saccharomyces cerevisiae strain mutant SM14 with 20 g/L glucose as the carbon source. These models are then extended to the study of a novel fed-batch system giving the ability to use flowrate and concentration of the feed stream to act as control variables. Dynamic optimization techniques are used to determine the optimal control actions governing the dilution rate and glucose concentration in order to minimize the time necessary to maximize the carotenoid productivity in the fed-batch operation. Additional constraints on the feed flowrate and glucose concentration are considered for this finite-horizon optimal control problem.

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