Genome-scale model-based feed-forward control of C. vulgaris improves efficiency of nitrate supplied to a fed-batch culture

Genome-Scale Model;Model Predictive Control;Microalgae;Chlorella;Chemical & Biomolecular Engineering

Yelsky, Jacob StephanBetenbaugh, Michael J ;

Johns Hopkins University

关键词: Genome-Scale Model;    Model Predictive Control;    Microalgae;    Chlorella;    Chemical & Biomolecular Engineering;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/60151/YELSKY-THESIS-2018.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Microalgae are widely recognized as promising biofuel feedstock due to their, short harvesting cycle, high photosynthetic efficiency, and high energy density.Lowering the production cost of algal-derived biofuels is critical to their viability as a sustainable fuel source.Nutrients found in algal medium, particularly nitrate, are key contributors to the production cost of algal biofuels.The cost of these nutrients are even more pronounced in controlled photobioreactor systems, which are unable to rely on environmental phenomena to supply nutrients. In order to optimize nutrients supplied to fed-batch algal cultures, a genome-scale model-based control algorithm was developed using the recently constructed genome-scale model iCZ946-T1 to control nitrate fed to C. vulgaris, a strain of microalgae identified as a promising candidate for biofuel production.This algorithm was validated using a novel simulation-based feed forward control method, in which simulated rapid cell density measurements were generated from experimental growth data.These simulated cell density measurements were run through the genome-scale model-based control algorithm, which generated predictions of how much nitrate should be fed to a fed-batch culture every fifteen minutes. The simulations predicted normal growth could be sustained with a 53% reduction of nitrate, compared to normal media. To validate these predictions, a culture was grown under the predicted nitrate feeding schedule.As predicted, growth was sustained in this culture while feeding only 140 mg/L of nitrate, 53% less nitrate than the 300 mg/L found in normal cell media. The macronutrient compositions of the cultures were examined to confirm that the validation culture was not growing under metabolic stress. A feedback control system, which is applicable to rector systems subject to dynamic conditions, such as open systems or outdoor photobioreactors, is also described.