Enhanced Algal Photosynthetic Photon Efficiency by Pulsed Light

Zarmi, Yair; Gordon, Jeffrey M.; Mahulkar, Amit; Khopkar, Avinash R.; Patil, Smita; Banerjee, Arun K.; Reddy, Badari Gade; Griffin, Thomas P.; Sapre, Ajit

doi:10.1016/j.isci.2020.101115

Cited by 21 publications

(38 citation statements)

References 61 publications

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“…For a batch cultivation system, Qiang et al (1998 ) found an increase in biomass productivity from 200 to 7.5 mm; however, we experimentally verified that the behavior of batch and continuous systems at ultra-thin light paths is considerably different. Experimental results and previous considerations show that an indefinite decrease in the reactor thickness cannot lead to an increase in cultivating performances in continuous systems and suggest the existence of an optimal light path value (as conceptualized in other studies ( Richmond et al, 2003 ; Zarmi et al, 2020 ).…”

Section: Resultssupporting

confidence: 63%

Microalgae growth in ultra-thin steady-state continuous photobioreactors: assessing self-shading effects

Saccardo

Bezzo

Sforza

2022

Front. Bioeng. Biotechnol.

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To disclose the net effect of light on microalgal growth in photobioreactors, self-shading and mixing-induced light–dark cycles must be minimized and discerned from the transient phenomena of acclimation. In this work, we performed experiments of continuous microalgal cultivation in small-scale photobioreactors with different thicknesses (from 2 to 35 mm): working at a steady state allowed us to describe the effect of light after acclimation, while the geometry of the reactor was adjusted to find the threshold light path that can discriminate different phenomena. Experiments showed an increased inhibition under smaller culture light paths, suggesting a strong shading effect at thicknesses higher than 8 mm where mixing-induced light–dark cycles may occur. A Haldane-like model was applied and kinetic parameters retrieved, showing possible issues in the scalability of experimental results at different light paths if mixing-induced light–dark cycles are not considered. To further highlight the influence of mixing cycles, we proposed an analogy between small-scale operations with continuous light and PBR operations with pulsed light, with the computation of characteristic parameters from pulsed-light microalgae growth mathematical modeling.

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Section: Resultssupporting

confidence: 63%

Microalgae growth in ultra-thin steady-state continuous photobioreactors: assessing self-shading effects

Saccardo

Bezzo

Sforza

2022

Front. Bioeng. Biotechnol.

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“…When discussing the regulatory effect of light on the growth of microalgae, as a rule, not the entire light flux is studied, but that part of it that has the greatest physiological activity. This radiation corresponds to the visible part of the spectrum in the wavelength range 400-700 nm and is called photosynthetically active radiation [46]. When characterizing the light conditions for microalgae growth, the light intensity, duration of lighting and the spectral composition of the light flux are taken into account.…”

Section: Light As An Environmental Factor Of Microalgae Growthmentioning

confidence: 99%

“…The duration of lighting is also of great importance, both from the point of view of ensuring maximum microalgae productivity, and for minimizing energy costs during cultivation. The practice of using continuous lighting or alternating light and dark cultivation cycles is known, including pulsed (blinking) lighting, which is characterized by a rapid change in light and dark periods [46,53,54]. The use of light and dark cultivation cycles is associated with the peculiarities of photosynthesis-a complex multistep process in which light-dependent photochemical reactions and dark reactions are distinguished, wherein the dark reaction of photosynthesis is not dependent on the presence of light [14].…”

Section: Light As An Environmental Factor Of Microalgae Growthmentioning

confidence: 99%

“…The growth and metabolism of photoautotrophic microalgae is greatly influenced by the duration and frequency of lighting [84]. When cultivating microalgae, both continuous lighting and alternation of light and dark cycles, as well as light flashes or pulsed lighting, are used [46]. It is assumed that the use of lighting systems with dark cycles can increase the productivity of microalgae by increasing the efficiency of light absorption and reduce energy consumption, which is important for increasing the profitability of biotechnological production of microalgae.…”

Section: Influence Of Duration and Frequency Of Lightingmentioning

confidence: 99%

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Influence of Light Conditions on Microalgae Growth and Content of Lipids, Carotenoids, and Fatty Acid Composition

Maltsev

Maltseva

Kulikovskiy

et al. 2021

Biology

189

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Microalgae are a valuable natural resource for a variety of value-added products. The growth of microalgae is determined by the impact of many factors, but, from the point of view of the implementation of autotrophic growth, light is of primary importance. This work presents an overview of the influence of light conditions on the growth of microalgae, the content of lipids, carotenoids, and the composition of fatty acids in their biomass, taking into account parameters such as the intensity, duration of lighting, and use of rays of different spectral composition. The optimal light intensity for the growth of microalgae lies in the following range: 26−400 µmol photons m−2 s−1. An increase in light intensity leads to an activation of lipid synthesis. For maximum lipid productivity, various microalgae species and strains need lighting of different intensities: from 60 to 700 µmol photons m−2 s−1. Strong light preferentially increases the triacylglyceride content. The intensity of lighting has a regulating effect on the synthesis of fatty acids, carotenoids, including β-carotene, lutein and astaxanthin. In intense lighting conditions, saturated fatty acids usually accumulate, as well as monounsaturated ones, and the number of polyunsaturated fatty acids decreases. Red as well as blue LED lighting improves the biomass productivity of microalgae of various taxonomic groups. Changing the duration of the photoperiod, the use of pulsed light can stimulate microalgae growth, the production of lipids, and carotenoids. The simultaneous use of light and other stresses contributes to a stronger effect on the productivity of algae.

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“…The author also explained how the photonic efficiency enhancement depends on the optical pulse and the photon flux density of time scales. More specifically, the key is through the correct timing of the algae cell light/dark cycle to avoid photosynthetic pathway jams [40]. The results from the previous literature explain the relationship between leaf photosynthesis and the L/D cycle in the light pulse process by considering the PIs pool.…”

Section: Discussionmentioning

confidence: 99%

The Effect Mechanism and Model Optimization of Pulsed Light Dark Duration on Lettuce

et al. 2021

Preprint

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Background: Despite its rapid development, the costs of crop artificial light source technology are still high. In addition, both the luminous efficiency and photosynthetic light supplement efficiency of the light source require further improvement. This study aims to improve the photosynthetic light supplement efficiency by altering the luminescence mode of the light source, transforming the conventional continuous supplementary light source into a pulse light source, and exploring how to further reduce energy consumption and improve the light supplement efficiency without influencing the light supplement effect of Lettuce.Results: For this purpose, Lettuce (Lactuca sativa L.) was selected as the experimental material to investigate the effects of varying the duty ratio, frequency and dark duration on the Pn (net photosynthetic rate) of leaves. The results revealed that Pn values under each duty ratio treatment increased with frequency and gradually stabilized to a level similar to that of continuous light. At higher duty ratios, the lettuce leaf Pn under pulse light reached a stable state at a lower frequency, with Pn leveling showing an overall upward trend with the decreasing dark period duration and a large increase in the early stage. For dark period durations lower than a certain value (0.000683594 s), variations in Pn among treatments were minimal, with a gradual increasing trend until no significant differences are observed with continuous light (CK); Under the D3 (weak light) condition, plants were easy to spindling(excessive growth)and exhibited narrow and slender leaves. Plants under the D2 condition (The duration period duration was 0.000465468s) presented the strongest roots and stems, with wide leaves and a compact growth. The following trend in Pn was observed across all duty ratios D2>D1 (0.000046547s)>CK>D3 (0.004654685s). Conclusions: The dominant influencing factor of the plant net photosynthetic rate was determined as the ratio of the frequency and duty ratio (i.e., dark period duration). Compared with continuous light, pulsed light is more beneficial to plant growth and utilization.

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Enhanced Algal Photosynthetic Photon Efficiency by Pulsed Light

Cited by 21 publications

References 61 publications

Microalgae growth in ultra-thin steady-state continuous photobioreactors: assessing self-shading effects

Microalgae growth in ultra-thin steady-state continuous photobioreactors: assessing self-shading effects

Influence of Light Conditions on Microalgae Growth and Content of Lipids, Carotenoids, and Fatty Acid Composition

The Effect Mechanism and Model Optimization of Pulsed Light Dark Duration on Lettuce

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