Characterization of newly isolated oleaginous microalga Monoraphidium sp. for lipid production under different conditions

Green microalga Monoraphidium sp. was isolated during the mass cultivation study of Ettlia sp., when it was found that the culture was dominated by smaller unidentified cells with high lipid content. The strain was identified and named as Monoraphidium sp. based on its morphological characterization under light and confocal microscopy followed by genomic characterization via 18s sequencing. The lipid content, fatty acid profiles, biomass and lipid productivity of microalga were examined under autotrophic cultivation condition using various CO₂ concentrations as well as different nitrogen sources. Isolated Monoraphidium sp. was found to have high lipid content of 28.92% determined via gas chromatography and sulfo-phospho-vanillin method (SPV). Lipid profile of the algal cells exhibited a suitable distribution of fatty acids for biodiesel production, with cultivation using urea producing particularly high quality of biodiesel. Therefore, the results suggest that Monoraphidium sp. is a promising feedstock for biodiesel production.