Effects of molten-salt/ionic-liquid mixture on extraction of docosahexaenoic acid (DHA)-rich lipids from Aurantiochytrium sp. KRS101

Abstract

In this study, lipid extraction from Aurantiochytrium sp. was performed using a molten-salt/ionic-liquid mixture. The total fatty acid content of Aurantiochytrium sp. was 478.8 mg/g cell, from which 145 mg/g cell (30.3% of total fatty acids) of docosahexaenoic acid (DHA) was obtained. FeCl3·6H2O showed a high lipid extraction yield (207.9 mg/g cell), when compared with that of [Emim]OAc, which was only 118.1 mg/g cell; notably however, when FeCl3·6H2O was mixed with [Emim]OAc (5:1, w/w), the yield was increased to 478.6 mg/g cell. When lipid was extracted by the FeCl3·6H2O/[Emim]OAc mixture at a 5:1 (w/w) blending ratio under 90 °C, 30 min reaction conditions, the fatty acid content of the extracted lipid was a high purity 997.7 mg/g lipid, with most of the DHA having been extracted (30.2% of total fatty acids). Overall, lipid extraction from Aurantiochytrium sp. was enhanced by the synergistic effects of the molten-salt/ionic-liquid mixture with different ions.

Ionic-Liquid-Mediated Extraction and Separation Processes for Bioactive Compounds: Past, Present, and Future Trends

“…151 were able to boost the yield of lipids extracted from Chlorella vulgaris using [C 4 C 1 im][CF 3 SO 3 ]-methanol as the best mixture (12.5%–19.0% of lipids extracted), which compares with the conventional method of Bligh and Dyer (10.6%–11.1% of lipids extracted). The results obtained showed that hydrophilic ILs are the best for these applications, 151 although other mixtures of interest can also be found in the literature (e.g., IL-water, 152,153 IL-molten salts, 154,155 and IL-IL). 156 A [N 0222 ][HSO 4 ]-subcritical water mixture extracted 73.63% of the total lipids, as compared to 60.44% with the conventional method of Bligh and Dyer, 152 while synergetic effects between two ILs or an IL and a molten salt lead to enhanced yields and good purity levels when compared to the corresponding pure compounds.…”

“…were able to boost the yield of lipids extracted from Chlorella vulgaris using [C 4 C 1 im]­[CF 3 SO 3 ]-methanol as the best mixture (12.5%–19.0% of lipids extracted), which compares with the conventional method of Bligh and Dyer (10.6%–11.1% of lipids extracted). The results obtained showed that hydrophilic ILs are the best for these applications, although other mixtures of interest can also be found in the literature (e.g., IL-water, , IL-molten salts, , and IL-IL) . A [N 0222 ]­[HSO 4 ]-subcritical water mixture extracted 73.63% of the total lipids, as compared to 60.44% with the conventional method of Bligh and Dyer, while synergetic effects between two ILs or an IL and a molten salt lead to enhanced yields and good purity levels when compared to the corresponding pure compounds. − Of particular interest is the approach of Olkiewicz et al, wherein lipids from two microalgae species, namely Chlorella vulgaris and Nannochloropsis oculata, were extracted using a [P (1OH)(1OH)(1OH)(1OH) ]Cl aqueous solution (at 80% w/w) at 100 °C for 24 h. The IL-based method proposed performs better than both the Bligh and Dyer method and Soxhlet extractions, in particular at extracting lipids from Chlorella vulgaris and for recovering a larger saponifiable fraction from Nannochloropsis oculata .…”

“…147 Other works from the same research group addressed the coextraction of compounds based on a similar approach, namely (i) a simultaneous extraction of bio-oil and fermentable sugars from jatropha and safflower biomass using [C 2 C 1 im][C 1 CO 2 ] and methanol as cosolvent; 148 (ii) bio-oil and phorbol ester corecovery from jatropha biomass using [C 2 C 1 im][C 1 SO 4 ] and methanol as cosolvent; 149 and (iii) lipid and fermentable sugar separation from Rhodosporidium toruloides with [C 2 C 1 im]-[C 1 CO 2 ]-methanol mixtures wherein the carbohydrates were recycled for yeast consumption. 150 Following a similar line of research, Kim et al 151 were able to boost the yield of lipids extracted from Chlorella vulgaris using 151 although other mixtures of interest can also be found in the literature (e.g., IL-water, 152,153 IL-molten salts, 154,155 and IL-IL). 156 A [N 0222 ][HSO 4 ]-subcritical water mixture extracted 73.63% of the total lipids, as compared to 60.44% with the conventional method of Bligh and Dyer, 152 while synergetic effects between two ILs or an IL and a molten salt lead to enhanced yields and good purity levels when compared to the corresponding pure compounds.…”

Efficient Extraction of a Docosahexaenoic Acid (DHA)-Rich Lipid Fraction from Thraustochytrium sp. Using Ionic Liquids

“…The consumption of omega-3 polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA, 22:6n-3) or eicosapentaenoic acid (EPA, 20:5n-3), has been linked to the prevention of neural disorders, cardiovascular diseases, arthritis, asthma, and dermatosis [ 1 , 2 , 3 , 4 ]. PUFAs are involved in many vital physiological functions and are important components of brain cell membranes [ 5 , 6 , 7 ].…”

“…Ionic liquids (ILs) have been shown to increase the lipid extraction efficiency from microalgae by dissolving both dry and wet microalgae under relatively mild conditions (80–140 °C) with and without a co-solvent ( Table 1 ) [ 1 , 30 , 31 ]. ILs are often described as “green” designer solvents with many desirable physical-chemical properties such as great thermal stability, low melting points, and negligible vapor pressure [ 32 ].…”