Thursday, August 2, 2007 - 8:50 AM
S162
Production of Gamma Linolenic Acid (GLA) in Transformed Yarrowia lipolitica
Lu-Te Chuang1, Dz-Chi Chen2, and Yung-Sheng Huang1. (1) Biotechnology, Yuanpei University, 306 Yuanpei Street, Hsin-Chu, Taiwan, (2) Yeastern Biotech, Co., Ltd., Fl. 6, No. 23-3, Lane 169, Kang Ning Street, Taipei, Taiwan
Gamma-linolenic acid (GLA), a valued n-6 polyunsaturated fatty acid (n-6 PUFA) primarily from evening primrose oil and borage oil, has been shown to exert various beneficial effects. It is known that GLA is derived from one of essential fatty acids (EFA), linoleic acid (LA), by the action of D6-desaturase. Previously, we have shown that bakers’ yeast could be transformed by inserting D6-desaturase gene from Mortierella alpine to produce GLA in the presence of LA in the medium. In this study, we transformed an non-conventional yeast strain, Yarrowia lipolytica, by inserting the D6-desaturase gene from M. alpine. Results showed that this process enabled Y. lipolytica to convert carbon source from culture medium directly to form transgenic oil containing GLA through fermentation. The transformed Yarrrowia yeasts successfully converted the endogenous LA to GLA. Under the culture condition set in this study, the conversion rate ([GLA] / [LA + GLA] x 100%) was approximately 65%. The overall yield of GLA in the transformed yeast was estimated to be about 5% of total yeast fatty acids. The transformed yeast could also use palmitoleic and oleic acid as the substrate to form 16:2n-6 and 18:2n-6, respectively, but at a lesser extent in comparison with LA as the substrate. The growth and lipid production of the transformed yeast were affected by incubation conditions, such as nitrogen source, culture temperature, pH value in medium, etc. Further studies are needed to improve the yield of fat production and rate of conversion.