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Fatty acid profile of Dunaliella tertiolecta in response to different selenium concentrations

Due to the increasing human population and the negative impact of fossil fuel combustion on the environment, there is an ever-increasing need for sustainable energy development [1]. Since microalgae offer several advantages (high growth rate, high oil content, etc), they have been considered a promising candidate for alternative renewable fuel sources (biodiesel, bioethanol, etc.). The two most important factors affecting biodiesel production, oil content, and microalgal fatty acids profile, are highly dependent upon the used microalgae species and cultivation conditions. Furthermore, studies have confirmed the beneficial effect of trace elements (Co, Cr, Mn, Mo, Cu, Fe, Zn) on microalgal growth and lipid content [2]. This research aimed to assess the dependence of total fatty acids content and profile in marine microalgae Dunaliella tertiolecta upon exposure to different concentrations of sodium selenite (Se) during two-stage cultivation. Total lipids were determined as total fatty acid methyl esters (FAME) by in-situ transesterification, while the FAME content was determined using gas chromatography [3]. According to the obtained results, the total FAME content of the control treatment group (no Se addition) was approximately 2-fold higher compared to the 20.00, 40.00 and 80.00 mg L-1 selenite treatment groups, which can be explained by the excessive exposure time of microalgae cells to Se which leads to a decrease in lipid synthesis. Furthermore, it was reported that in the control medium, γ-linoleic acid (C18:3 (c6, c9, c12) and palmitic acid (C16:0) were present in a higher proportion. Increasing the Se concentration in the culture medium increases the proportion of C16:0, while the proportion of C18:3 (c6, c9, c12) decreases, which indicates that the addition of Se in a culture medium, as a stress factor, contributes to the synthesis of monounsaturated fatty acids (MUFA). Since highly saturated fatty acids (e.g. C16:0) contribute to the satisfactory value of cetane number and oxidative stability parameters, which represent important biodiesel standards, it can be concluded that the present study reports valuable data regarding the influence of Se on fatty acids content and profile in microalgae D. tertiolecta and therefore potentially sustainable biodiesel production.

microalgae ; lipids ; selenite ; biodiesel

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