Abstract: A method for producing a microbial oil includes genetically modifying a labyrinthulid which belongs to the genus Parietichytrium or the genus Schizochytrium by disrupting and/or silencing a ?4 desaturase gene, a C20 elongase gene, and/or a C18 elongase gene, or by being transformed with an ?3 desaturase gene; culturing the labyrinthulid; and collecting the microbial oil from the labyrinthulid. The labyrinthulid has an activity of synthesizing DHA via a PUFA-PKS pathway in an amount of not more than 1/100 of a total amount of DHA synthesized in the labyrinthulid or no activity of producing PUFAs via the PUFA-PKS pathway, and the labyrinthulid has an activity of producing PUFAs via an endogenous elongase-desaturase pathway.

Abstract: A method for producing a microbial oil includes genetically modifying a labyrinthulid which belongs to the genus Parietichytrium or the genus Schizochytrium by disrupting and/or silencing a ?4 desaturase gene, a C20 elongase gene, and/or a C18 elongase gene, or by being transformed with an ?3 desaturase gene; culturing the labyrinthulid; and collecting the microbial oil from the labyrinthulid. The labyrinthulid has an activity of synthesizing DHA via a PUFA-PKS pathway in an amount of not more than 1/100 of a total amount of DHA synthesized in the labyrinthulid or no activity of producing PUFAs via the PUFA-PKS pathway, and the labyrinthulid has an activity of producing PUFAs via an endogenous elongase-desaturase pathway.

Abstract: A method for producing a microbial oil includes steps of: genetically modifying a labyrinthulid by disrupting and/or silencing a gene, or by transforming another gene in addition to the disruption and/or gene silencing of the gene, and culturing the labyrinthulid, such that a fatty acid composition accumulated in the labyrinthulid comprises an increased EPA content; and collecting the microbial oil having the increased EPA content from the labyrinthulid. The labyrinthulid before the modification is selected from (A) a labyrinthulid belonging to the genus Parietichytrium or genus Schizochytrium and having very weak or no activity of producing PUFAs via a PUFA-PKS pathway; and (B) a labyrinthulid belonging to the genus Thraustochytrium in which a host PUFA-PKS gene is disrupted or silenced to a very weak level. The increased EPA content is preferably not less than 11.5% of a total fatty acid composition.

Abstract: A method for producing a microbial oil includes the steps of: genetically modifying a labyrinthulid by disrupting and/or silencing a gene, or by transforming another gene in addition to the disruption and/or gene silencing of the gene; culturing the labyrinthulid, such that a fatty acid composition accumulated in the labyrinthulid comprises an increased EPA content; and collecting the microbial oil having the increased EPA content from the labyrinthulid. The increased EPA content is not less than 3.3% of a total fatty acid composition.

Abstract: A method for producing a microbial oil includes steps of: genetically modifying a labyrinthulid by disrupting and/or silencing a gene, or by transforming another gene in addition to the disruption and/or gene silencing of the gene, and culturing the labyrinthulid, such that a fatty acid composition accumulated in the labyrinthulid comprises an increased EPA content; and collecting the microbial oil having the increased EPA content from the labyrinthulid. The labyrinthulid before the modification is selected from (A) a labyrinthulid belonging to the genus Parietichytrium or genus Schizochytrium and having very weak or no activity of producing PUFAs via a PUFA-PKS pathway; and (B) a labyrinthulid belonging to the genus Thraustochytrium in which a host PUFA-PKS gene is disrupted or silenced to a very weak level. The increased EPA content is preferably not less than 11.5% of a total fatty acid composition.

Abstract: A microbial oil is obtained from Labyrinthulomycetes in which a gene for fatty acid biosynthesis has been disrupted or an expression of the gene has been inhibited to highly accumulate the fatty acid. The microbial oil typically contains: (a) 1.5% or more of arachidonic acid (AA) based on a total amount of fatty acid; (b) 0.2% or more of dihomo-?-linolenic acid (DGLA) based on the total amount of fatty acid; (c) 0.04% or more of eicosatetraenoic acid (ETA) based on the total amount of fatty acid; (d) 3.8% or more of eicosapentaenoic acid (EPA) based on the total amount of fatty acid; (e) 13.7% or less of n-6 docosapentaenoic acid (n-6DPA) based on the total amount of fatty acid; and (f) 43.9% or less of docosahexaenoic acid (DHA) based on the total amount of fatty acid.

Abstract: A microbial oil is obtained from Labyrinthulomycetes in which a gene for fatty acid biosynthesis has been disrupted or an expression of the gene has been inhibited to highly accumulate the fatty acid. The microbial oil typically contains: (a) 1.5% or more of arachidonic acid (AA) based on a total amount of fatty acid; (b) 0.2% or more of dihomo-?-linolenic acid (DGLA) based on the total amount of fatty acid; (c) 0.04% or more of eicosatetraenoic acid (ETA) based on the total amount of fatty acid; (d) 3.8% or more of eicosapentaenoic acid (EPA) based on the total amount of fatty acid; (e) 13.7% or less of n-6 docosapentaenoic acid (n-6DPA) based on the total amount of fatty acid; and (f) 43.9% or less of docosahexaenoic acid (DHA) based on the total amount of fatty acid.

Abstract: A Labyrinthulid microorganism capable of producing a PUFA only through the elongase-desaturase pathway. A Labyrinthulid microorganism which has no ability of producing a PUFA through the endogenous PUFA-PKS pathway or has the ability at an extremely weak level and which has an ability of producing a PUFA through the endogenous elongase-desaturase pathway. The Labyrinthulid microorganism is a microorganism belonging to the genus Parietichytrium or Parietichytrium.

Abstract: To provide a transformation method for producing a stramenopile organism having an improved unsaturated fatty acid production capability by disrupting a gene of the stramenopile organism or inhibiting the expression of the gene in a genetically engineering manner. [Solution] A method for transforming a stramenopile organism, which comprises disrupting a gene of the stramenopile organism or inhibiting the expression of the gene in a genetically engineering manner, and which is characterized in that the stramenopile organism is selected from Thraustochytrium aureum, Parietichytrium sarkarianum, Thraustochytrium roseum and Parietichytrium sp. and the gene to be disrupted or of which the expression is to be inhibited is a gene associated with the biosynthesis of a fatty acid.

Abstract: To provide a transformation method for producing a stramenopile organism having an improved unsaturated fatty acid production capability by disrupting a gene of the stramenopile organism or inhibiting the expression of the gene in a genetically engineering manner. [Solution] A method for transforming a stramenopile organism, which comprises disrupting a gene of the stramenopile organism or inhibiting the expression of the gene in a genetically engineering manner, and which is characterized in that the stramenopile organism is selected from Thraustochytrium aureum, Parietichytrium sarkarianum, Thraustochytrium roseum and Parietichytrium sp. and the gene to be disrupted or of which the expression is to be inhibited is a gene associated with the biosynthesis of a fatty acid.

Abstract: To provide a transformation method for producing a stramenopile organism having an improved unsaturated fatty acid production capability by disrupting a gene of the stramenopile organism or inhibiting the expression of the gene in a genetically engineering manner. [Solution] A method for transforming a stramenopile organism, which comprises disrupting a gene of the stramenopile organism or inhibiting the expression of the gene in a genetically engineering manner, and which is characterized in that the stramenopile organism is selected from Thraustochytrium aureum, Parietichytrium sarkarianum, Thraustochytrium roseum and Parietichytrium sp. and the gene to be disrupted or of which the expression is to be inhibited is a gene associated with the biosynthesis of a fatty acid.