An Identifiable State Model To Describe Light Intensity Influence on Microalgae Growth

Kinetics generally describes bio‐(chemical) reaction rates in dependence on substrate concentrations. Kinetics for microalgae is often adapted from heterotrophs and lacks mechanistic foundation, e.g. for light harvesting. Using and understanding kinetic equations as the representation of intracellular mechanisms is essential for reasonable comparisons and simulations of growth behavior. Summarizing growth kinetics in one equation does not yield reliable models. Piecewise linear or rational functions may mimic photosynthesis irradiance response curves, but fail to represent the mechanisms. Our modeling approach for photoautotrophic growth comprises physical and kinetic modules with mechanistic foundation extracted from the literature. Splitting the light submodel into the modules for light distribution, light absorption, and photosynthetic sugar production with independent parameters allows the transfer of kinetics between different reactor designs. The consecutive anabolism depends among others on nutrient concentrations. The nutrient uptake kinetics largely impacts carbon partitioning in the reviewed stoichiometry range of cellular constituents. Consecutive metabolic steps mask each other and demand a maximum value understandable as the minimum principle of growth. These fundamental modules need to be clearly distinguished, but may be modified or extended based on process conditions and progress in research. First, discussion of kinetics helps to understand the physiological situation, for which ranges of parameter values are given. Second, kinetics should be used for photobioreactor design, but also for gassing and nutrient optimization. Numerous examples are given for both aspects. Finally, measuring kinetics more comprehensively and precisely will help in improved process development.

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“…Based on chlorophyll reaction kinetics PSU and time constants not directly measurable [17,19,77,78] [see also this review]…”

Section: Hanmentioning

confidence: 99%

Microalgal kinetics — a guideline for photobioreactor design and process development

Schediwy

Trautmann

Steinweg

et al. 2019

Engineering in Life Sciences

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“…For τ = 0.3 s, the actual time constant fitted from , the highest frequencies are filtered whilst lower ones induce variations in the internal variable i and in the related growth rate μ ( i ).…”

Section: Resultsmentioning

confidence: 99%

“…More refined dynamic models accounting for the dynamic response of the photon absorption chain have been published, e.g., by Nicolaou, Bernard and co‐workers . However, their intrinsic complexity in terms of number of variables limits their use to homogeneous reactors , and leads to parameter identification issues.…”

Section: Introductionmentioning

confidence: 99%

How Mixing and Light Heterogeneity Impact the Overall Growth Rate in Photobioreactors

et al. 2019

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The microalgae growth rate in photobioreactors responds with inertia to light stimuli. Here, light variations experienced by the algae are accessed through a coupling of an irradiance field calculation and a Lagrangian particle tracking. The response of algae to fluctuating light is then described by a relaxation model involving a single time constant, the value of which is identified from published data. The overall growth rate is calculated as the sum of individual growth rates of all particles. Instantaneous adaptation and full integration asymptotic behaviors are recovered whilst a finite time constant reveals that the overall growth rate is dependent both on mixing and light distribution. This methodology thus quantitatively relates the design parameters to the photobioreactor performance.

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“…Rosso et al , Franz et al ), and, most importantly, light (e.g. Grima et al , Rubio et al , Bernardi et al ). Some models not only describe the static effect of light on growth, but aim at representing the dynamics of photosynthesis, accounting for regulation and inhibition (Eilers and Peeters , Han et al ).…”

Section: Model‐based Approaches To Generate Strains With Improved Permentioning

confidence: 99%

The potential of quantitative models to improve microalgae photosynthetic efficiency

Perin

Bellan

Bernardi

et al. 2019

Physiologia Plantarum

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The massive increase in carbon dioxide concentration in the atmosphere driven by human activities is causing huge negative consequences and new sustainable sources of energy, food and materials are highly needed. Algae are unicellular photosynthetic microorganisms that can provide a highly strategic contribution to this challenge as alternative source of biomass to complement crops cultivation. Algae industrial cultures are commonly limited by light availability, and biomass accumulation is strongly dependent on their photon‐to‐biomass conversion efficiency. Investigation of algae photosynthetic metabolism is thus strategic for the generation of more efficient strains with higher productivity. Algae are cultivated at industrial scale in conditions highly different from the natural niches they adapted to and strains development efforts must fully consider the seminal influence on productivity of regulatory mechanism of photosynthesis as well as of cultivation parameters like cells concentration, light distribution in the culture, mixing, nutrients and carbon dioxide availability. In this review we will focus in particular on how mathematical models can account for the complex influence of all environmental parameters and can be exploited for development of improved algae strains.

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An Identifiable State Model To Describe Light Intensity Influence on Microalgae Growth

Cited by 31 publications

References 40 publications

Microalgal kinetics — a guideline for photobioreactor design and process development

Microalgal kinetics — a guideline for photobioreactor design and process development

How Mixing and Light Heterogeneity Impact the Overall Growth Rate in Photobioreactors

The potential of quantitative models to improve microalgae photosynthetic efficiency

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