title: Flashing light as growth stimulant in cultivation of green microalgae, Chlorella sp. utilizing airlift photobioreactor.
abstract: One of the main limitations of productivity in photobioreactor is the inefficient conversion of the available light into biomass. Photoautotrophic cells such as microalgae only absorb a small fraction of supplied illumination due to limitation of its photosystem's (PS) absorbing rate. However, phenomenon of Flashing Light Effect (FLE) allows microalgae to utilize strong light exceptionally through intermittent exposure. Exposure of strong light at correct frequency of light and dark photoperiod would allow two pigment-protein complexes, PSI and PSII to be at the equilibrium mid-point potential to allow efficient light conversion. Narrow range of optimum frequency is crucial since overexposure to strong light would injured photosynthetic apparatus whereas longer dark period would contributed to loss of biomass due to triacylglycerol metabolism. The behaviour of microalgae towards various illumination conditions of FLE was determined at batch Photobioreactor (PBR) by varying the aeration flow rate: 16.94, 33.14 and 49.28 mL sec(-1) which yield, respectively the light exposure time of 3.99, 1.71 and 1.1 seconds per cycle. Maximum cell density in FLE-PBR was significantly higher at the exponential phase as compared to the continuously illuminated culture (p = 5.62 x 10(-5), a = 0.05) under the flow rate of 25.07 mL sec(-1). Maximum cell density yield of FLE-PBR and continuously illuminated PBR was, respectively 3.1125 x 10(7) and 2.947 x 10(7) cells mL(-1). Utilization of FLE as an innovative solution to increase the efficiency of microalgae to convert light into chemical energy would revolutionize the microalgae culture, reduce the time for cultivation and produce higher maximum biomass density.
authors: Department of Engineering Science, Faculty of Science and Technology, Universiti Malaysia Terengganu, Jln. Tok Jembal, 21030 Terengganu, Malaysia.
authors: L
authors: L
authors: Fathurrahman
authors: Department of Engineering Science, Faculty of Science and Technology, Universiti Malaysia Terengganu, Jln. Tok Jembal, 21030 Terengganu, Malaysia.
authors: A H Siti
authors: AH
authors: Hajar
authors: Department of Engineering Science, Faculty of Science and Technology, Universiti Malaysia Terengganu, Jln. Tok Jembal, 21030 Terengganu, Malaysia.
authors: D Wan Nur
authors: DW
authors: Sakinah
authors: Department of Engineering Science, Faculty of Science and Technology, Universiti Malaysia Terengganu, Jln. Tok Jembal, 21030 Terengganu, Malaysia.
authors: Z
authors: Z
authors: Nurhazwani
authors: Department of Engineering Science, Faculty of Science and Technology, Universiti Malaysia Terengganu, Jln. Tok Jembal, 21030 Terengganu, Malaysia.
authors: J
authors: J
authors: Ahmad
mesh_terms: D018533:Biomass; D002708:Chlorella / Q000145:classification / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D004734:Energy Metabolism / Q000528:radiation effects; D008027:Light; D009038:Motion; D010775:Photic Stimulation; D058433:Photobioreactors; D017440:Photoperiod; D010788:Photosynthesis / Q000528:radiation effects; D045331:Photosystem I Protein Complex / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000378:metabolism; D011156:Population Density; D013997:Time Factors; D014280:Triglycerides / Q000378:metabolism
chemical_list: D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D014280:Triglycerides