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Maximum photosynthetic yield of green microalgae in photobioreactors.

Zijffers JW, Schippers KJ, Zheng K, Janssen M, Tramper J, Wijffels RH - Mar. Biotechnol. (2010)

Bottom Line: Using the model of Pirt (New Phytol 102:3-37, 1986), a biomass yield on light energy of 0.78 and 0.75 g mol photons⁻¹ and a maintenance requirement of 0.0133 and 0.0068 mol photons g⁻¹ h⁻¹ were found for D. tertiolecta and C. sorokiniana, respectively.The observed yield decreases steeply at low light supply rates, and according to this model, this is related to the increase of the amount of useable light energy diverted to biomass maintenance.Consequently, for the design of a photobioreactor, we should maintain a relatively high specific light supply rate.

View Article: PubMed Central - PubMed

Affiliation: Bioprocess Engineering, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.

ABSTRACT
The biomass yield on light energy of Dunaliella tertiolecta and Chlorella sorokiniana was investigated in a 1.25- and 2.15-cm light path panel photobioreactor at constant ingoing photon flux density (930 µmol photons m⁻² s⁻¹). At the optimal combination of biomass density and dilution rate, equal biomass yields on light energy were observed for both light paths for both microalgae. The observed biomass yield on light energy appeared to be based on a constant intrinsic biomass yield and a constant maintenance energy requirement per gram biomass. Using the model of Pirt (New Phytol 102:3-37, 1986), a biomass yield on light energy of 0.78 and 0.75 g mol photons⁻¹ and a maintenance requirement of 0.0133 and 0.0068 mol photons g⁻¹ h⁻¹ were found for D. tertiolecta and C. sorokiniana, respectively. The observed yield decreases steeply at low light supply rates, and according to this model, this is related to the increase of the amount of useable light energy diverted to biomass maintenance. With this study, we demonstrated that the observed biomass yield on light in short light path bioreactors at high biomass densities decreases because maintenance requirements are relatively high at these conditions. All our experimental data for the two strains tested could be described by the physiological models of Pirt (New Phytol 102:3-37, 1986). Consequently, for the design of a photobioreactor, we should maintain a relatively high specific light supply rate. A process with high biomass densities and high yields at high light intensities can only be obtained in short light path photobioreactors.

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Spectral composition of the fluorescent tubes after passing the first water jacket (Lynx LE 55 W, 535 mm, Sylvania, Danvers, MA, USA). The emission spectrum was normalized on a quantum basis
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Fig2: Spectral composition of the fluorescent tubes after passing the first water jacket (Lynx LE 55 W, 535 mm, Sylvania, Danvers, MA, USA). The emission spectrum was normalized on a quantum basis

Mentions: The reactors were illuminated on one side using ten compact fluorescent tubes (Lynx LE 55 W, 535 mm, Sylvania, Danvers, MA, USA). The PAR photon flux density on the reactor surface was measured several times throughout the experiment using a Li-190sa quantum sensor (LI-COR, USA). The light absorption and reflection in passing the first water jacket was determined in an empty reactor and was corrected for in determining the photon flux density into the photobioreactor. The spectral composition (Fig. 2) of the light was determined behind the water jacket (IRRAD 2000 fiber-optic spectroradiometer, TOP sensor systems, Eerbeek, the Netherlands).Fig. 2


Maximum photosynthetic yield of green microalgae in photobioreactors.

Zijffers JW, Schippers KJ, Zheng K, Janssen M, Tramper J, Wijffels RH - Mar. Biotechnol. (2010)

Spectral composition of the fluorescent tubes after passing the first water jacket (Lynx LE 55 W, 535 mm, Sylvania, Danvers, MA, USA). The emission spectrum was normalized on a quantum basis
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2991169&req=5

Fig2: Spectral composition of the fluorescent tubes after passing the first water jacket (Lynx LE 55 W, 535 mm, Sylvania, Danvers, MA, USA). The emission spectrum was normalized on a quantum basis
Mentions: The reactors were illuminated on one side using ten compact fluorescent tubes (Lynx LE 55 W, 535 mm, Sylvania, Danvers, MA, USA). The PAR photon flux density on the reactor surface was measured several times throughout the experiment using a Li-190sa quantum sensor (LI-COR, USA). The light absorption and reflection in passing the first water jacket was determined in an empty reactor and was corrected for in determining the photon flux density into the photobioreactor. The spectral composition (Fig. 2) of the light was determined behind the water jacket (IRRAD 2000 fiber-optic spectroradiometer, TOP sensor systems, Eerbeek, the Netherlands).Fig. 2

Bottom Line: Using the model of Pirt (New Phytol 102:3-37, 1986), a biomass yield on light energy of 0.78 and 0.75 g mol photons⁻¹ and a maintenance requirement of 0.0133 and 0.0068 mol photons g⁻¹ h⁻¹ were found for D. tertiolecta and C. sorokiniana, respectively.The observed yield decreases steeply at low light supply rates, and according to this model, this is related to the increase of the amount of useable light energy diverted to biomass maintenance.Consequently, for the design of a photobioreactor, we should maintain a relatively high specific light supply rate.

View Article: PubMed Central - PubMed

Affiliation: Bioprocess Engineering, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.

ABSTRACT
The biomass yield on light energy of Dunaliella tertiolecta and Chlorella sorokiniana was investigated in a 1.25- and 2.15-cm light path panel photobioreactor at constant ingoing photon flux density (930 µmol photons m⁻² s⁻¹). At the optimal combination of biomass density and dilution rate, equal biomass yields on light energy were observed for both light paths for both microalgae. The observed biomass yield on light energy appeared to be based on a constant intrinsic biomass yield and a constant maintenance energy requirement per gram biomass. Using the model of Pirt (New Phytol 102:3-37, 1986), a biomass yield on light energy of 0.78 and 0.75 g mol photons⁻¹ and a maintenance requirement of 0.0133 and 0.0068 mol photons g⁻¹ h⁻¹ were found for D. tertiolecta and C. sorokiniana, respectively. The observed yield decreases steeply at low light supply rates, and according to this model, this is related to the increase of the amount of useable light energy diverted to biomass maintenance. With this study, we demonstrated that the observed biomass yield on light in short light path bioreactors at high biomass densities decreases because maintenance requirements are relatively high at these conditions. All our experimental data for the two strains tested could be described by the physiological models of Pirt (New Phytol 102:3-37, 1986). Consequently, for the design of a photobioreactor, we should maintain a relatively high specific light supply rate. A process with high biomass densities and high yields at high light intensities can only be obtained in short light path photobioreactors.

Show MeSH