A New Labyrinthulid Isolate That Produces Only Docosahexaenoic Acid

Abstract

We show here that a new labyrinthulid strain, L72, isolated from a fallen leaf in the Seto Inland Sea of Japan, produced only docohexaenoic acid (DHA) among all the long-chain polyunsaturated fatty acids (LCPUFAs). The main fatty acid composition was 16:0 (28.9%), 18:0 (7.2%), 18:1 (5.7%), 18:2 (10.4%), and DHA (45.9%) without any other LCPUFA. The lipid content of the strain was 27.4%. The cells had many lipid bodies, which were densely located in all of the cells. On phylogenetic analysis using the 18S rDNA sequence, the strain was located in the labyrinthulids group, forming a monophyletic group with Labyrinthula sp. (strain s) and Labyrinthuila sp. (strain L59). We further tested the culture optimization of strain L72 to evaluate the ability of the strain to produce DHA. The optimum salt concentration and the temperature of the strain were 100% of artificial seawater and 20 degrees C. Strain L72 could grow well on soybean oil (SBO) or soybean lecithin (SBL) as the carbon source. When 20 g/l of SBL was added to the medium, DHA production reached the maximum amount at 0.67 g/l for 14 d. The two important facts, that the strain can use SBL as the main nutrient and contains only DHA among the LCPUFAs, will be of great advantage for industry.

Eelgrass pathogen Labyrinthula zosterae synthesizes essential fatty acids

“…For marine phytoplankton, Galloway & Winder (2015) synthesized data for FA contents in 208 species and found the greatest DHA content in dinoflagellates (21 ± 1 µg mg −1 DW, 17 ± 9%TFA), exceeded by Lz cells on SSA in our study (111.9 ± 46.8 µg mg −1 DW, 36.6 ± 11.6%TFA). Lz's DHA content does, expectedly, fall with many other heterotrophic protists researched for industrial LCPUFA production, including Lz's relatives (5 to over 50% lipid; Kumon et al 2006, Armenta & Valentine 2013. With greater ecological relevance, 5 planktonic heterotrophic protists studied by Chu et al (2008Chu et al ( , 2009 fed biologically relevant diets (bacteria or phytoplankton) contained DHA at ~5 to 17%TFA.…”

“…Lz belongs to the Labyrinthulomycetes, heterotrophic protists characterized by their ectoplasmic net (Raghukumar 2002). The Labyrinthulomycetes include diverse pathogens (Raghukumar 2002) but are also known for abundantly producing long-chain polyunsaturated fatty acids (LCPUFA), namely eicosapentaenoic acid (EPA, 20:5ω-3) and docosahexaenoic acid (DHA, (Kumon et al 2006, Armenta & Valentine 2013. Such LCPUFA and some other fatty acids (FA), including linoleic acid (LIN, 18:2ω-6) and α-linolenic acid (ALA, 18:3ω-3), are important nutritional components for many consumers that rely on them for diverse physiological needs ranging from cell membrane fluidity to nervous system function (Parrish 2009).…”

Single‐Cell Oils as a Source of Omega‐3 Fatty Acids: An Overview of Recent Advances

“…While vegetable oils are added to complement the carbon source, in one case, soybean oil, or soybean lecithin, was used as the only carbon source for Labyrinthula sp. strain L72 [41]. Soybean oil at a concentration of 5 g/L produced 0.32 g/L of DHA while soybean lecithin, at the same concentration, only produced 0.17 g/L.…”

“…For example, Thraustochytrid striatum can grow with a salinity level between 2 and 50 g/L [25]. Salt can be obtained from several sources; natural sea water is often used at salt concentrations from 50 to 100 % of sea water [11,13,41,63]. Other times, sea water is artificially created by the addition of various minerals such as magnesium, iron, potassium, and various others [64].…”

Effect of culture conditions on the growth and docosahexaenoic acid production from Aurantiochytrium limacinum strain 85

“…La principal fuente comercial del DHA, son los peces grasos marinos de agua fría como arenque, caballa, sardina, salmón y ancho veta, así como sus aceites procesados, pero es una fuente limitada, que no puede satis facer la creciente demanda del DHA, además este aceite es muy variable en composición y calidad (De Swaaf, Sijtsma and Pronk 2003), pudiendo estar contaminado con metales pesados, bifenilos policlorados y dioxinas, (Hooper et al 2006, Pauly et al 2002, Ratledge, 2004, estando restringido en formulas infantiles (Kumon et al 2006), pudiendo agregar que tiene problemas asociados con su olor característico, sabor desagradable, y la mala estabilidad oxida tiva (Spolaore et al 2006).…”