Fatty acids composition of microalgae Chlorella vulgaris can be modulated by varying carbon dioxide concentration in outdoor culture
Varying culture methods of Chlorella vulgaris (CV) has been associated with different nutrient composition. The aim of this study was to investigate the fatty acid contents and other nutrients of CV subjected to various culturing conditions. We found that CV cultured under 24 h light and 10% CO2 showed the best growth rates and contained higher lipid, protein and moisture contents compared to other culture conditions. Interestingly, the content of fatty acids of CV was dependent on the amount of CO2. Fatty acid analysis of CV by gas chromatography-mass spectrometry (GC-MS) showed the presence of cis-10-pentadecanoic acid (C15:1), palmitic acid (C16:0), palmitoleic acid (C16:1), heptadecanoic acid (C17:0), stearic acid (C18:0), oleic acid (C18:1n9c), linoleic acid (C18:2n6c), linolenic acids (C18:3n3) and arachidic acid (C20:0). Remarkably, polyunsaturated fatty acids (linoleic and linolenic acids) are found in abundance compared to other fatty acids in CV. The concentrations of palmitic, oleic, linoleic and linolenic acids increased when the amount of carbon dioxide was raised from 1 to 10% under both culture conditions (12 and 24 h light). This study shows the possibility of modifying lipid contents in freshwater microalgae by varying the amount of carbon dioxide and light.
Key words: Chlorella vulgaris, microalgae, fatty acids, vitamins, minerals, carbon dioxide.