Simultaneous production of flavonoids and lipids from Chlorella vulgaris and Chlorella pyrenoidosa

Flavonoids are the secondary metabolites synthesized by microalgae and have diverse applications in various fields. The present study compares among two microalgal strains,Chlorella vulgaris(CV) andChlorella pyrenoidosa(CP), for the production of flavonoids and lipids, which were cultivated in mixotrophic as well as autotrophic modes. This study also focuses on the role ofl-phenylalanine as a supplement to enhance flavonoids. The current work establishes the relation between nitrates, external carbon, andl-phenylalanine for enhanced production of flavonoids and lipids. The extracted flavonoids were found to be maximum in CP-autotrophic mode followed by CV-mixotrophic mode with 138 mu g/ml and 118 mu g/ml, respectively. The common flavonoids observed with both the microalgal strains were quercetin, catechin, and p-coumaric acid. In comparison, the production of the maximum lipid of 23.7% was reported with mixotrophic operation in CV, followed by CP (19.4%). The scavenging activity of the extracted flavonoids was determined using a hydrogen peroxide assay and was found to be in the range of 63-73% at all experimental conditions. CP was found to produce more flavonoids in autotrophic mode, whereas mixotrophic mode showed maximum production of lipids and flavonoids in the CV. The simultaneous production of high value-added products, viz., flavonoids and lipids, not only paves a pathway for the biorefinery approach but also elevates the commercial potential during scale-up. Graphical abstract

Automated summary

This study compares the production of flavonoids and lipids in two microalgal strains, Chlorella vulgaris (CV) and Chlorella pyrenoidosa (CP), cultivated in mixotrophic and autotrophic modes. The role of L-phenylalanine in enhancing flavonoid production is also investigated. The results show that CV produces the highest lipid yield in mixotrophic mode, while CP produces more flavonoids in autotrophic mode.