Green Gold: Sustainable Biodiesel Production and Bioactive Compounds Extraction from Microalgae

Abstract

Microalgae have attracted significant interest from both scientific and industrial sectors as a potential source of high-lipid feedstock for biodiesel production. Current research has mainly emphasized on the production of biodiesel from algal biomass, with a focus on collecting, isolating, screening, and characterizing suitable algal species. In this regard, a total of sixty-seven microalgal strains were isolated from both freshwater and marine sources across various regions. The screening for high-lipid microalgae strains was conducted using the Nile Red method to identify neutral lipid droplets. Out of the sixty-seven strains, four promising biodiesel-producing strains Chlorococcum aquaticum, Scenedesmus obliquus, Nannochloropsis oculata, and Chlorella pyrenoidosa were selected based on their high lipid and biomass accumulation, Among the prescreened algal strains, Scenedesmus obliquus exhibited the highest biomass at 1.32±0.023 g/L, while Chlorella pyrenoidosa had a significantly higher lipid content of 15.27%. Further GC-MS (Gas Chromatography-Mass Spectrometry) analysis was conducted to identify the free fatty acids present in the algal oil. The FAME (Fatty Acid Methyl Ester) profile revealed the presence of several key fatty acids, including palmitic acid (16:0), palmitoleic acid (C16:1), stearic acid (C18:0), and oleic acid (C18:1). Together, these fatty acids indicate that the algal strains are rich in both saturated and unsaturated fatty acids, which are key for producing high-quality biodiesel. The combination of these fatty acids suggests that the algal oil could meet the required standards for biodiesel production, offering good energy content, stability, and favorable cold-flow properties. Thus, these micro-algal strains are promising candidates for sustainable biodiesel production.