Incorporation of eicosapentaenoic and docosahexaenoic acids by a yeast (FO726A)

摘要

An eicosapentaenoic acid (EPA)-and docosahexaenoic acid (DHA)-incorporating yeast, FO726A, was putatively identified as Candida guilliermondii on the basis of morphological, physiological and biochemical characteristics. Culture conditions for FO726A were investigated with respect to cell mass productivity, cellular accumulation of total lipid, triglyceride (TG), EPA and DHA. When grown at 20 deg C for 24h in an optimal medium containing 1 g scrap fish oil, the yeast yielded 820mg dry cells which consisted of 40.7% lipid, 40.2% protein and 14.1% carbohydrate. The lipid (334mg) consisted of 300mg Tg (36.6% of dry cells), 23.2mg EPA (2.8%) and 54.8mg DHA (6.7%), and the recovery rates of EPA and DHA from the fish oil were 27.1 and 43.6%, respectively. The positional distributions of fatty acids in the TG from the yeast were then investigated and compared with those in the TG from the fish oil. The EPA and DHA in the fish oil were concentrated more in the sn-1,3 positions (8.8 and 13.7%, respectively) than in the sn-2 position (3.7 and 10.8%, respectively). In the case of the TG from the yeast, EPA was present to a greater extent in the sn-1,3 positions than in the sn-2 position. In contrast, DHA was preferentially present in the sn-2 position, approximately twice that in the sn-1,3 positions.