Summary:
Microalgae are single-celled or colonial microorganisms found in all ecosystems in the environment. They have the ability to produce a variety of organic compounds such as lipids, carbohydrates, proteins and pigments, and in combination with their short reproduction time, they are important organisms in applied fields such as the production of biofuel or food supplements. In particular, microalgae produce large amounts of lipids, mainly polyunsaturated omega-3 and omega-6 fatty acids, which offer many benefits to humans, such as prevention of cardiovascular diseases, nervous disorders, etc., and contribute to healthy development during embryonic and neonatal age. However, the human body cannot produce them on its own so the discovery of new production sources is important.
In the present study, 2 strains of the genus Tetraselmis, strains R1-2 and R1-3, and 2 strains of the genus Dunaliella, strains D7 and D8, isolated from sites in Northern Greece, were studied. Initially, the growth curve of each strain was determined, and then cell lipids were isolated, identified and quantified.
It was observed that the four strains have different growth curves, with strain R1-2 showing the highest proliferation rate. At day 9, the cells were harvested, extracted to obtain total lipids, then their fatty acids, in the form of methyl esters, were separated and finally analyzed by gas chromatography-mass spectrometry. All 4 strains studied, showed a rich lipid profile, and several differences were observed between the fatty acids of each strain. In all 4 strains, a high percentage of polyunsaturated fatty acids was observed, in particular lipids that possess important properties and are often used in dietary supplements and other formulations.
Overall, strain R1-3 showed the best profile compared to the other strains. Although the proliferation time is not the optimum compared to strain R1-2 belonging to the same genus, it produces a significant number of cells in culture. Moreover, its lipid profile is rich in fatty acids, especially polyunsaturated, as well as in other important fatty acids such as C16:0, C16:1, C18:1, etc. Moreover, an important observed difference is that strain R1-2 has a significantly lower percentage of polyunsaturated fatty acids (PUFA) as compared to the other 3 strains, while, on the contrary, it has comparatively higher percentage of monounsaturated fatty acids (MUFA). Furthermore, the omega-3 fatty acids content of strain R1-2 is significantly lower than that of the other strains, while omega-6 fatty acids are at the same level with strain R1-3. As a result, the omega-3/omega-6 ratio is quite low compared to the other strains, indicating that it is likely that consumption of strain R1-3 is more beneficial, as the omega-3/omega-6 ratio is higher, as suggested in the literature.
In conclusion, R1-3, appears to be the most suitable for use in food supplements. In contrast, strain R1-2 is probably not a useful strain for consumption due to its low levels of PUFA, specifically omega-3 fatty acids. The Dunaliella strains, although producing significant amounts of lipids and in particular omega-3 fatty acids, have as a limiting factor their multiplication rate, as in culture they do not produce a high number of cells a fact observed in Tetraselmis strains. Since the two genera have potential in the production of food supplements. further studies should be undertaken examining for example by effect of the culture conditions.
Keywords:
Microalgae, Lipid profile, SAFA, MUFA, PUFA, ω-3 and ω-6 fatty acids, Strain Kinetics Curves
