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

Abstract. Fakhri M, Riyani E, Ekawati AW, Arifin NB, Yuniarti A, Widyawati Y, Saputra IK, Samuel PD, Arif MZ, Hariati AM. 2021. Biomass, pigment production, and nutrient uptake of Chlorella sp. under different photoperiods. Biodiversitas 22: 5344-5349. Chlorella sp. is well-known as a functional feed in fish culture and has been utilized in the food industry. In phototrophic cultivation, photoperiod plays a fundamental part in the growth and pigment content of microalgae. This work was purposed to evaluate the effect of light:dark cycle on the growth rate, production of biomass and pigment and nutrient utilization of Chlorella sp. Four photoperiods (8:16, 12:12, 18:6, and 24:0 h light:dark regimes) under a constant light intensity of 4500 lux were applied in this study. The results demonstrated that increasing light duration led to increased cell growth, biomass, and pigment production of Chlorella sp. The best cell concentration, specific growth rate, and biomass production were 28.5 x 106 cells mL-1, 1.47 day-1, and 0.815 g L-1 dry weight, respectively, under continuous illumination. The maximum chlorophyll a of 19.205 mg L-1 and carotenoid of 4.656 mg L-1 were obtained at 24:0 h photoperiod. The highest uptake of nitrate (66.331%) and phosphate (76.191%) by Chlorella sp. were achieved under 24 h light regime. Improving the uptake of nutrients resulted in enhanced growth and pigment content of Chlorella sp. We conclude that continuous illumination is the best photoperiod to produce biomass and pigment and improve the nutrient removal of Chlorella sp.