A biphasic photobioreactor system for consecutive extraction of lipids and carotenoids from pre-hydrolysed microalgae and evaluation of its biodiesel potential

A green extraction method is developed using partially hydrolysed microalgal cells grown in biocompatible solvent for simultaneous cultivation and extraction of bioproducts from a highly efficient permeabilized microalgal cell with enhanced biomass and lipid content for potential use in biodiesel production. Incomplete digestion of cell wall was achieved by regulating the incubation time of the enzymatic pretreatment of the microalgal cells. 15.77% increase in lipid content was seen when untreated cells were cultured with biocom-patible solvent, while cultivation of these enzymatically pretreated cells with biocompatible solvent, the lipid content increased by 53.33% and 22% higher carotenoid content was observed as compared to conventional extraction. The total fatty acids obtained after 1st and 2nd extractions in untreated samples were 67.82%, while those in enzymatically partially digested samples were 91.94%. The untreated and partially enzymatically predigested strain showed suitable properties for quality biodiesel production as per international recommen-dations. The cost benefit analysis of the overall process showed the use of biocompatible solvent coupled to enzymatically predigested biomass was a favorable option as compared to conventional extraction.

Automated summary

A green extraction method was developed using partially hydrolysed microalgal cells grown in biocompatible solvent, allowing simultaneous cultivation and extraction of bioproducts. The enzymatic pretreatment of the microalgal cells achieved incomplete digestion of the cell wall. Cultivating the enzymatically pretreated cells with biocompatible solvent resulted in a 53.33% increase in lipid content and a 22% higher carotenoid content compared to conventional extraction. The cost benefit analysis showed that this method was favorable for biodiesel production.