Influence of light intensity and photoperiod on energy efficiency of biomass and pigment production of Spirulina (Arthrospira platensis)

Abstract

Biomass and photosynthetic pigments production of cyanobacteria, in particular Spirulina (Arthrospira platensis), depend on light intensity. Production cost of Spirulina cultivation in photobioreactor illuminated with LED is strongly related to light cost. This work is aimed to evaluate the effects of light intensity and photoperiod on the energy efficiency of biomass and pigment production of Spirulina platensis UTEX 1926. Cultures illuminated with white light-emitting diodes (LED) were carried out in batch mode cultivation. Three lighting scenarios with different light intensities were tested: two with a constant light intensity at 80 and 160 μmol · m−2 · s−1 and one with modulated light intensity. Concerning photoperiod, three cycles of light:dark (h:h) (24:00, 20:04 and 16:08) were studied under light intensity at 160 μmol · m−2 · s−1. Concerning Spirulina biomass and pigment production (phycocyanin, chlorophyll and carotenoids), it is found that the lower intensity tested allows a substantial increase of the process energy efficiency. Concerning the influence of the photoperiod, it has been found that the longer the off time is (up to 08 h 00 a day), the higher is the energy efficiency for Spirulina biomass as well as for pigmentary production.

Biomass, pigment production, and nutrient uptake of Chlorella sp. under different photoperiods

“…These results are consistent with Khoeyi et al (2012), who also found that biomass production of C. vulgaris increased with enhancing light duration. Similar results were also observed in Niangoran et al (2021), who reported the biomass of Spirulina platensis increased with increasing light duration with the best photoperiod of 24 light regimes. Xue et al (2011) explained that photo limitation is crucial for inhibiting microalga growth since the cells do not receive sufficient light.…”

“…Furthermore, enhancing carotenoid content under a 24 h light regime is related to the function of carotenoids in the photosynthesis process, which is to alleviate and assist the pigment-protein complex in the thylakoid membrane (Takaichi 2011;Yusof et al 2021). Variation of photoperiods had a different effect on the pigment content of microalgae, and it is probably dependent on the adaptation of cells to the different environments (Kendirlioglu et al 2015;Niangoran et al 2021).…”

Light Modulation for Bioactive Pigment Production in Synechocystis salina

“…The use of new light technologies, such as LED, provides a sustainable alternative to conventional lamps (e.g., halogen, fluorescent, high pressure, sodium) [ 16 , 17 ]. Despite the higher cost of installation (but with declining prices throughout the years), LEDs have a long life and entail low energy usage compared to conventional lighting.…”

“…Several studies employing LED technology have shown their efficiency towards cyanobacterial culture and pigment modulation (e.g., Arthrospira spp.) [ 17 , 19 , 20 ]. The intensity and light wavelength can be tuned toward production of specific bioactive pigments, in terms of quantity and quality, along with biomass production [ 17 ].…”

“…[ 17 , 19 , 20 ]. The intensity and light wavelength can be tuned toward production of specific bioactive pigments, in terms of quantity and quality, along with biomass production [ 17 ]. However, optimal conditions are always dependent on the species chosen for that purpose.…”