The term "algae" is used to refer to over 72,500 identified aquatic species. The size of algae is up to tens of meters, however, most (about 80%) of the species are much smaller - they comprise the microalgae group. Microalgae are rich in nutrients and biologically active substances such as proteins, carbohydrates, lipids, vitamins, pigments and others. These components are widely used in food, cosmetic, chemical and energy industries. Biotechnology of microalgae has multiple advantages: they are a renewable and sustainable resource, more productive than terrestrial plants due to their high growth rate and lack of seasonality of cultivation, and also less sensitive to environmental conditions.
Nowadays there is a growing practical interest in the lipids and fatty acids from microalgae. At the moment, there are a limited number of species from which lipids can be obtained in good yield; the oil content in the most promising of them is about 20-50% calculated on dry matter. Fatty acids are composed of carbon, hydrogen and oxygen atoms. Depending on the bonds between carbon atoms, they are classified into two groups - saturated (all bonds are single) and unsaturated (there is at least one double bond). Polyunsaturated fatty acids - the famous Ω-6 and Ω-3 families - are especially useful for human health. They cannot be formed in the body and must be supplied with food; a balanced diet with the correct polyunsaturated fatty acids amount reduces the risk of heart and vascular diseases, arthritis and depression.
Microalgae are an important source of fatty acids: most of them accumulate saturated palmitic and monounsaturated oleic acids, but, for example, spirulina is a reservoir for linoleic and γ-linolenic acids (Ω-6). Moreover, the fatty acid profile can vary for the same species depending on the cultivation conditions and the composition of the nutrient medium. In the nearest future polyunsaturated fatty acids from microalgae will play a significant role in the industrial sector due to their biological activity and positive effects on human health.
The work of Russian scientists was aimed at studying the qualitative and quantitative composition of fatty acids of microalgae typical for water bodies (Lake Vištytis, Lake Chaika, Lake Yantarnoye, Curonian Lagoon, Strait of Baltiysk, Baltic Sea coast, Lake Krasnoye) of the Kaliningrad region. The authors took samples of water and soil, cultivated the microorganisms from the probes on a nutrient medium and sequenced them for the accurate identification of the species. After that, the optimal conditions for the cultivation of microalgae in terms of maximal lipids accumulation were chosen. The cells were centrifuged then, the cell walls were destroyed and lipids were separated from the resulting mass. The composition of fatty acids was determined using high performance liquid chromatography - a separation method based on the different distribution of substances between two immiscible phases, in which the liquid, the mobile phase, moves with high hydraulic resistance.
It turned out that the most saturated fatty acids were characteristic of the microalgae Chlorella vulgaris and Dunaliella salina. In the Dunaliella salina and Arthrospira platensis, the maximum degree of unsaturated fatty acids ranged from 15 to 23%. Lipid complex of microalgae included neutral lipids, polar lipids, unsaponifiable substances and other impurities. Thus, these organisms represent a promising route for practical implementation.
"Studies have shown that microalgal biomass is a prospective product as it is a great new source of lipids. The possibility of their use for the production of dietary supplements for humans and feed additives for animals is encouraging. Despite the potential of this idea, there are still technologies that have to be developed for the reduction of the cost of lipids from microalgae," says Olga Babich, Director of the Institute of Living Systems of the Immanuel Kant Baltic Federal University, Doctor of Technical Sciences.
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Journal
Biomolecules