Extraction of squalene as value-added product from the residual biomass of Schizochytrium mangrovei PQ6 during biodiesel producing process

Today microalgae represent a viable alternative source of squalene for commercial application. The species Schizochytrium mangrovei, a heterotrophic microalga, has been widely studied and provides a high amount of squalene, polyunsaturated fatty acids and has good profiles for biodiesel production. Our work was aimed at examining the squalene contents in Vietnam's heterotrophic marine microalga S. mangrovei PQ6 biomass and residues of the biodiesel process from this strain. Thin-layer chromatography and high-performance liquid chromatography (HPLC) methods were successfully applied to the determination of squalene in S. mangrovei PQ6. The squalene content and production of S. mangrovei PQ6 reached 33.00 ± 0.02 and 33.04 ± 0.03 mg g−1 of dry cell weight; and 0.992 g L−1 and 1.019 g L−1 in 30 and 150 L bioreactors, respectively after 96 h of fermentation. In addition, squalene was also detected in spent biomass (approximately 80.10 ± 0.03 mg g−1 of spent biomass) from the S. mangrovei PQ6 biodiesel production process. The structure of squalene in residues of the biodiesel process was confirmed from its nuclear magnetic resonance spectra. The results obtained from our work suggest that there is tremendous potential in the exploitation of squalene as a value-added by-product besides biodiesel from S. mangrovei PQ6 to reduce biodiesel price.