The novel strategy for enhancing growth and lipid accumulation in Chlorella vulgaris microalgae cultured in dairy wastewater by monochromatic LEDs and melatonin

• Published in: Journal of applied phycology 2023-04, Vol.35 (2), p.593-601
• Main Authors: Maleki Samani, Mohammad Sadegh, Mansouri, Hakimeh
• Format: Article
• Language: English
• Subjects: Accumulation; Algae; Aquatic microorganisms; Biomass; Biomedical and Life Sciences; Carbohydrates; Chlorella; Chlorella vulgaris; Culture media; Dairy industry wastewaters; Ecology; Fatty acids; Freshwater & Marine Ecology; Life Sciences; Light emitting diodes; Lipids; Melatonin; Metabolites; Microalgae; Phytoplankton; Pigments; Plant Physiology; Plant Sciences; Polyunsaturated fatty acids; Productivity; Wastewater; White light
• ISSN: 0921-8971; 1573-5176
• DOI: 10.1007/s10811-022-02898-6

Microalgae are known as renewable feedstock for biomass and lipid production. The ability to grow microalgae in wastewater makes their cultivation potentially cost-effective. In this work, the potential of using melatonin and monochromatic light-emitting diodes (LED) to increase lipid accumulation and biomass productivity of microalgae Chlorella vulgaris grown in dairy wastewater was investigated. The experiments were performed under red, blue, green, and white LEDs with melatonin in dairy wastewater. In no-melatonin samples, the maximum biomass productivity was observed in the algae treated with red and blue LEDs, respectively. According to the changes in biomass productivity, the highest content of pigments, carbohydrates, proteins, and lipids was obtained in algae grown with red LED and the lowest amounts of these compounds were observed in white light. Adding 10 µM melatonin to the culture medium improved all results compared to no-melatonin samples. Simultaneous treatment of red LED with 10 µM melatonin increased biomass productivity two-fold compared to white LED without melatonin and was selected as the optimal treatment. The lipid content under optimal treatment reached 44.63% DW compared to the control sample with 23.00% DW. The amount of monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) increased by 22 and 8% compared to the control. The percentage of saturated fatty acids (SFAs) decreased from 85.58% in the control samples to 56.93% in the optimal treatment. These results show that red LED can be a new economic treatment to increase the biomass and metabolites of C. vulgaris microalgae in dairy wastewater.