Selective Enrichment of Monounsaturated and Polyunsaturated Fatty Acid Production Through Phosphorus Adjustment Strategy in a Novel Marine Microalga Tetraselmis astigmatica

Abstract

This study provides a technological demonstration of enhanced production of monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA) and eicosapentaenoic acid (EPA) from a novel marine microalgae Tetraselmis astigmatica through the phosphorus (P) adjustment strategy. The microalga was isolated from the coast of the Bay of Bengal and was genetically identified through 18S rRNA sequencing. This microalga was grown in different concentrations (1, 5, 10, 20, 30 mg/L) of phosphorus. The highest biomass yield (347.0 mg/L) and biomass productivity (21.7 mg/L/day) were achieved at 30 mg/L, while the maximum lipid yield (105.8 mg/L) and productivity (6.6 mg/L/day) were attained at 10 mg/L phosphorus concentration. Analysis of the fatty acid profile revealed that the microalgae produce a maximum of 9.8% of EPA (ω-3 PUFA), an essential fatty acid for human health, in the higher (30 mg/L) P-supplemented condition. Further, the MUFA content was significantly enhanced (78%) by P-limitation (1 mg/L) with respect to the repletion (30 mg/L), whereas PUFA content was enhanced (21%) by P-supplementation (30 mg/L) with respect to the phosphorus-limited (1 mg/L) condition. The biodiesel produced under P-limitation (1 mg/L) had a higher level of saturated fatty acids (SFAs), resulting in better quality (improved cetane number, iodine value) compared to biodiesel produced under P-supplemented conditions. This P-adjustment strategy provides a targeted approach by using a phosphorus-limited condition (1 mg/L) for selective enrichment of MUFA and SFA fractions in the biomass of Tetraselmis astigmatica (for biodiesel production) and by using a P-supplemented condition (10 mg/L) for enrichment of the PUFA fraction (for food application).

Graphical Abstract