Effect of different wavelengths of LED light on the growth, chlorophyll, β-carotene content and proximate composition of Chlorella ellipsoidea

Arpan Baidya; Taslima Akter; Md Rabiul Islam; A K M Azad Shah; Md Amzad Hossain; Mohammad Abdus Salam; Sulav Indra Paul

doi:10.1016/j.heliyon.2021.e08525

Effect of different wavelengths of LED light on the growth, chlorophyll, β-carotene content and proximate composition of Chlorella ellipsoidea

Heliyon. 2021 Dec 3;7(12):e08525. doi: 10.1016/j.heliyon.2021.e08525. eCollection 2021 Dec.

Authors

Arpan Baidya¹, Taslima Akter¹, Md Rabiul Islam¹, A K M Azad Shah², Md Amzad Hossain¹, Mohammad Abdus Salam³, Sulav Indra Paul⁴

Affiliations

¹ Department of Aquaculture, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur 1706, Bangladesh.
² Department of Fisheries Technology, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur 1706, Bangladesh.
³ Department of Genetics and Fish Breeding, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur 1706, Bangladesh.
⁴ Institute of Biotechnology and Genetic Engineering, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur 1706, Bangladesh.

Abstract

Chlorella ellipsoidea is a freshwater green microalga that has great prospect for the sustainable development of aquaculture industry. Microalgae require optimal lighting conditions for efficient photosynthesis. The key to cost-effective algal biomass production is to optimize algae growth conditions. This study aimed to investigate the effects of various wavelengths viz. white (380-750 nm), green (510 nm), blue (475 nm), and red (650 nm) light-emitting diodes (LEDs) on the growth, pigment content (chlorophyll-a, chlorophyll-b, and β-carotene), and proximate composition of C. ellipsoidea with a photoperiod of 12 h:12 h light: dark cycle under indoor environmental conditions. C. ellipsoidea was cultured in Bold's Basal Medium for 18 days. The cell density (125.36×10⁵ cells ml^-1), cell dry weight (58.9 ± 4.57 mg L^-1), optical density (1.66 ± 0.08 g L^-1), chlorophyll-a (7.31 ± 0.04 μg ml^-1), chlorophyll-b (2.73 ± 0.13 μg ml^-1), and β-carotene (0.39 ± 0.04 μg ml^-1) content of C. ellipsoidea were significantly (P < 0.05) higher at 15^th-day when cultured under blue LED light exposure. Significantly lower growth and nutritional values were obtained under red LED light exposure compared to the control and other LEDs spectra. In Pearson correlation analysis, the cell density and cell dry weight values showed a strong positive correlation with the values of pigment contents of C. ellipsoidea in all the treatments. The LEDs light spectra showed significant effects on proximate composition of C. ellipsoidea. Protein and lipid contents of C. ellipsoidea were significantly higher in blue LED growth conditions compared to white, green, and red LEDs. C. ellipsoidea cells were 3-7.04 μm in size and the maximum area of the cell was 38.94 μm² in blue LED treatment. Results of this study demonstrated that blue LED light spectra was the most suitable condition to induce nutritionally rich biomass production of C. ellipsoidea, which can be used as a potential source of fish feed towards sustainable aquaculture.

Keywords: Biomass production; Blue LED; Chlorella ellipsoidea; Pigment content; Proximate composition.