Evaluating the efficiency of biodiesel production from marine microbial consortium

A photosynthetic marine microalgae consortium (PMMC) was evaluated as a biodiesel feedstock, cultivated in BG-11 medium prepared with distilled water (PMMCDW) and seawater (PMMCSW), yielding final biomass concentrations of 5.17 g/L and 5.26 g/L, respectively. Chitosan-assisted harvesting was optimized via Response Surface Methodology, yielding peak efficiencies of 96.3% for PMMCDW (pH 5.5, 0.5 mL chitosan, 60 min) and 89.8% for PMMCSW (pH 3, 0.5 mL chitosan, 35 min). Lipid extraction by Bligh-Dyer and Soxhlet methods showed significantly higher yields with the Bligh-Dyer approach; PMMCDW (2.5 L) achieved a maximum lipid content of 50.44%, compared to 9.09–21% via Soxhlet. Extracted lipids were converted to fatty acid methyl esters (FAMEs) by direct transesterification. GC-MS confirmed characteristic FAME ions (m/z 57, 83) with retention times of ∼3.875 min, while FTIR corroborated ester functional groups (C = O at 1744.58 cm−1; C–H at 2925.33 and 2856.29 cm−1). PMMCDW demonstrated superior harvesting efficiency and lipid recovery despite comparable biomass production between the two-cultivation media. However, scalability and extraction variability remain key challenges, underscoring the need for standardized protocols to advance microalgae-based biodiesel systems.