Research press release


Nature Biotechnology

Sustainable production of fish oil fatty acids



酵母 Yarrowia lipolytica は大量培養がしやすく、天然にかなりの量の油を生産するが、Quinn Zhuたちは、この酵母を遺伝子操作してEPAを生産させようとした。この酵母に非常に効率の高いEPA生産経路を組み込むためには、21個もの外来遺伝子の導入と、酵母本来の遺伝子1個のノックアウトが必要だった。その結果、この新しい酵母株では、細胞の乾燥重量の最大30%、脂質の半分以上がEPAになったという。Yarrowia lipolyticaはすでにヒトの栄養補助食品の商業生産に利用され、養殖サケにEPAを供給する飼料の原料としても利用されている。

A genetically engineered type of yeast provides an abundant and sustainable supply of eicosapentanoic acid (EPA), one of the most vital components of fish oil, reports a study published online this week in Nature Biotechnology. This oil is available as a dietary supplement and as an enrichment to fish feed, enabling the farmed salmon on sale in stores in the United States to be sustainably produced for the first time.

Fish oils have long been recognized for their beneficial effects on human health, but as marine fish stocks are already under great pressure, sustainable sources to satisfy the ever-growing demand for these oils are needed. The health benefits of fish oil are largely attributed to the fact that they are rich in certain fatty acids, especially omega-3 long chain polyunsaturated fatty acids. These molecules are not made by fish but by marine microorganisms that fish eat. Despite intensive efforts, growing these microorganisms on an industrial scale has proven difficult.

Quinn Zhu and colleagues genetically engineered a yeast, Yarrowia lipolytica, which can be easily grown in large quantities and naturally produces substantial amounts of oil, to make EPA. To generate such a highly efficient production pathway, they needed to introduce 21 foreign genes into the yeast and to knock out one natural yeast gene. The authors report that up to 30% of the cell dry weight and more than half of the lipid of the new yeast strain consists of EPA. Yarrowia lipolytica is already used commercially to produce human nutritional supplements and as a feedstock to provide EPA to farmed salmon.

doi: 10.1038/nbt.2622


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