Production of polyunsaturated fatty acids by microorganisms

利用微生物作为长链多不饱和脂肪酸（PUFAs）的实际来源有许多优点。经过对多种微生物的筛选，发现真菌菌丝体是C_<20 b> PUFAs的新的丰富来源，具有重要的饮食和药理意义。在常规碳水化合物培养基中，土壤分离物高山Mortierella 1S-4以4.3 g/L（274 mg/g干菌丝体）的速度产生花生四烯酸（ARA）。该值占从菌丝中提取的脂质中总脂肪酸的65%以上。二碳五烯酸（EPA）也可在较低温度（即低温）下生长。， 12 . [c]。发现这种温度依赖性EPA的形成是由于一种酶的激活，该酶在低温下催化ARA的n-3位置的去饱和。真菌将含有α -亚麻酸（ALA）的油，如亚麻籽油和紫苏油转化为含有EPA的油，其浓度为1.88 g EPA/L。这种转化与生长温度无关。当在香油中生长时，同样的真菌产生2.17 g DGLA/L的二同型γ -亚麻酸（DGLA）， ARA产量明显下降。发现这是由于芝麻素和相关木脂素化合物对delta5 -去饱和酶的特异性抑制。

There are many advantages of using microorganisms as practical sources of long chain polyunsaturated fatty acids(PUFAs). After screening a wide variety of microorganisms, fungal mycelia were found to be new and rich sources of C_<20> PUFAs of dietary and pharmacological importance. A soil isolate, Mortierella alpina 1S-4, produced arachidonic acid(ARA)at 4.3 g/L(274 mg/g dry mycelia)in a conventional carbohydrate medium. This value accounted for more than 65% of the total fatty acids in the extracted lipids from the mycelia. Eicosapentaenoic acid(EPA)was also produced when M.alpina was grown at lower temperatures(i.e., 12ﾟC). This temperature-dependent formation of EPA was found to be due to the activation of an enzyme, which catalyzes desaturation at the n-3 position of ARA by low temperature. The fungus converted oils containing alpha-linolenic acid(ALA), such as linseed oil and perilla oil, to an oil containing EPA with a concentration of 1.88 g EPA/L.This conversion was independent of the growth temperature. When grown in the presence of sesame oil, the same fungus produced dihomo-gamma-linolenic acid(DGLA)at a level of 2.17 g DGLA/L, with an accompanying marked decrease in ARA production. This was found to be due to specific inhibition of the DELTA5-desaturase by sesamin and related lignan compounds present in the oil.