Sodium bicarbonate augmentation enhances lutein biosynthesis in green microalgae Chlorella pyrenoidosa

Abstract

Abstract The present study was carried out to investigate the effects of different concentrations of sodium bicarbonate (0, 50, 100, 150 and 200 mM) on the biosynthesis of lutein and lipids and also the expression of genes involved in lutein carotenogenesis in Chlorella pyrenoidosa. The algal extract from cultures treated with different concentrations of sodium bicarbonate was analyzed using high-performance liquid chromatography (HPLC) for lutein quantification. HPLC results revealed a three-fold increase of lutein in C. pyrenoidosa culture grown in 100 mM concentration (4.84 ± 0.56 mg/g of DCW), followed by 50 mM concentration (4.21 ± 0.11 mg/g of DCW) supplemented cultures compared to 150 mM and 200 mM concentration (2.32 ± 0.093 mg/g of DCW and 2.31 ± 0.114 mg/g of DCW) and control culture (1.45 ± 0.18 mg/g of DCW). The expression analysis of phytoene desaturase, lycopene cyclase and carotenoid hydroxylase genes also showed a significant up regulation in their expression when supplemented with sodium bicarbonate. Lipid yield was observed to be increased significantly when supplemented with sodium bicarbonate. Therefore, sodium bicarbonate (100–150 mM) can be used as a potential dissolved inorganic carbon source for enhancing lutein and lipid production during large scale cultivation of C. pyrenoidosa cultures.