title: Photon up-conversion increases biomass yield in Chlorella vulgaris.
abstract: Photon up-conversion, a process whereby lower energy radiations are converted to higher energy levels via the use of appropriate phosphor systems, was employed as a novel strategy for improving microalgal growth and lipid productivity. Photon up-conversion enables the utilization of regions of the solar spectrum, beyond the typical photosynthetically active radiation, that are usually wasted or are damaging to the algae. The effects of up-conversion of red light by two distinct sets of up-conversion phosphors were studied in the model microalgae Chlorella vulgaris. Up-conversion by set 1 phosphors led to a 2.85 fold increase in biomass concentration and a 3.2 fold increase in specific growth rate of the microalgae. While up-conversion by set 2 phosphors resulted in a 30% increase in biomass and 12% increase in specific intracellular neutral lipid, while the specific growth rates were comparable to that of the control. Furthermore, up-conversion resulted in higher levels of specific intracellular reactive oxygen species in C. vulgaris. Up-conversion of red light (654 nm) was shown to improve biomass yields in C. vulgaris. In principle, up-conversion can be used to increase the utilization range of the electromagnetic spectrum for improved cultivation of photosynthetic systems such as plants, algae, and microalgae.
authors.affiliation: Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, India.
authors.forename: Kavya R
authors.initials: KR
authors.lastname: Menon
authors.forename: Steffi
authors.initials: S
authors.lastname: Jose
authors.forename: Gadi K
authors.initials: GK
authors.lastname: Suraishkumar
mesh_terms: D018533:Biomass; D001709:Biotechnology / Q000379:methods*; D048408:Chlorella vulgaris / Q000254:growth & development* / Q000378:metabolism / Q000528:radiation effects*; D050356:Lipid Metabolism; D058086:Microalgae / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D017785:Photons; D010788:Photosynthesis
keywords: Chlorella vulgaris; Lipid productivity; Photon up conversion; Photosynthetically active radiation; Reactive species