Dynamic Modeling of Microalgae Growth and Lipid Production under Transient Light and Nitrogen Conditions
journal contributionposted on 10.09.2019, 17:44 authored by Diyuan Wang, Yi-Chun Lai, Amanda L. Karam, Francis L. de los Reyes, Joel J. Ducoste
We developed a new dynamic model to characterize how light and nitrogen regulate the cellular processes of photosynthetic microalgae leading to transient changes in the production of neutral lipids, carbohydrates, and biomass. Our model recapitulated the versatile neutral lipid synthesis pathways via (i) carbon reuse from carbohydrate metabolism under nitrogen sufficiency and (ii) fixed carbon redirection under nitrogen depletion. We also characterized the effects of light adaptation, light inhibition hysteresis, and nitrogen limitation on photosynthetic carbon fixation. The formulated model was calibrated and validated with experimental data of Dunaliella viridis cultivated in a lab-scale photobioreactor (PBR) under various light (low/moderate/high) and nitrogen (sufficient/limited) conditions. We conducted the identifiability, uncertainty, and sensitivity analyses to verify the model reliability using the profile likelihood method, the Markov chain Monte Carlo (MCMC) technique, and the extended Fourier Amplitude Sensitivity Test (eFAST). Our model predictions agreed well with experimental observations and suggested potential model improvement by incorporating a lipid degradation mechanism. The insights from our model-driven analysis helped improve the mechanistic understanding of transient algae growth and bioproducts formation under environmental variations and could be applied to optimize biofuel and biomass production.
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sensitivity analysesnitrogen sufficiencymodel reliabilitybiomass productionMarkov chain Monte CarloNitrogen Conditionslight inhibition hysteresislipid synthesis pathwayslab-scale photobioreactorphotosynthetic carbon fixationDynamic Modelinglight adaptationFourier Amplitude Sensitivity TestPBRalgae growthmodel recapitulatedmodel improvementnitrogen limitationbioproducts formationLipid Productionnitrogen depletionprofile likelihood methodphotosynthetic microalgaeMicroalgae Growthlipid degradation mechanismDunaliella viridisMCMCmodel-driven analysiscarbon redirectionmodel predictionsTransient Lightcarbohydrate metabolism