Synergistic effect of photonic modulation and nutrient deprivation on lipid accumulation in Scenedesmus sp. GUEco1020: A potent microalga for biodiesel production

In the present global energy crisis and depletion in nonrenewable energy sources, it is utmost necessary to find alternative renewable energy sources to sustain lives. Microalgae emerge as a promising renewable and sustainable alternative in the quest for renewable energy due to their higher lipid accumulation and desirable fatty acid (FA) composition that can further be enhanced by subjecting the microalgal cells to nutrient deprivation, as it directly influences biodiesel properties. Additionally, the strategic application of combined stress conditions also increases all these raw materials for biodiesel. Therefore, the present investigation has been undertaken to understand the synergistic effect of photonic modulation and nutrient deprivation on lipid accumulation and biofuel properties in Scenedesmus sp. GUEco1020. The result revealed a significant increase in lipid accumulation under phosphorus-deprived conditions, with total and neutral lipid content increasing by 317.35 % ( p < 0.001) and 128.71 % (p < 0.001), respectively. Remarkably, the synergistic effect of photonic modulation (PM) and phosphorus starvation (PS), resulted in 48.68 % and 73.42 % higher productivity in total and neutral lipid as compared to the phosphorus deprivation. Furthermore, GCMS analysis also disclosed a marked increase in SFAs content to 55.69 %, along with elevated levels of MUFAs (13.4 %) and PUFAs (25.8 %) under combined condition of PM and PS. The enhanced accumulation of specific fatty acids namely, C18:1 (5.9 %), C18:2 (11.4 %) and C18:3 (12.3 %), contribute to improving the cetane number (CN) and oxidative stability (OS) of the FAME derived from Scenedesmus sp. GUEco1020. Moreover, the other elevated biodiesel properties including High Heating Value (HHV), Iodine Value (IV), Saponification Value (SV), Degree of Unsaturation (DU) and Cloud Point (CP), justified different national and international specifications for biodiesel (EN 14214, ASTM D 6751 and IS 15607) establishing Scenedesmus sp. GUEco1020 as the best renewable and sustainable alternative to conventional fuel. • Scenedesmus sp. GUEco1020 can be a suitable feedstock for 3rd generation biodiesel. • 191.87 % higher increased lipid productivity in phosphorus-starved condition than nitrogen. • In synergistic effect of photonic modulation and phosphorus-starved condition lipid productivity increases up to 48.68 %. • 73.42 % of higher neutral lipid was estimated under combined application of photonic modulation and phosphorous starvation • Studied biodiesel properties met the requirement provided by the standard specification for biodiesel.