深黄被孢霉催化转化十八醇合成不饱和脂肪酸

Converting Octadecanol to Unsaturated Fatty Acids Catalyzed by Mortierella Isbellina

深黄被孢霉催化转化十八醇合成不饱和脂肪酸在优化转化条件下所得产物分析表明 ,干细胞中含油脂 4 7.5 % ,蛋白质 31 .5 % ,碳水化合物 2 8.9% .十八醇转化率为 6 7.2 % ,油脂选择性为 30 .6 % ,产率2 0 .6 % .油脂中脂肪酸的选择性为 :棕榈酸 4 .0 0 % ,棕榈油酸 0 .81 % ,硬脂酸 0 .95 % ,油酸 2 0 .75 % ,亚油酸 1 .95 % ,亚麻酸 2 .1 9% .催化转化条件下的研究表明 ,底物浓度越低 ,油脂和不饱和脂肪酸的选择性越好 ,当十八醇质量分数为 0 .5 %时 ,油脂和不饱和脂肪酸的选择性达到最大值 ;培养基 p H为中性时 ,获得了最大的油脂选择性和收率 ;33℃时醇转化率达最大值 88% ,2 3℃油脂产率达最大值 9.7% .Mg2 +对不饱和脂肪酸的生成有显著影响 ,当培养基中 [Mg2 +]=2 5 mmol/L时 ,获得了最大的油脂选择性 ( 2 5 .7% )和产率 ( 1 7.6 % )

Mortierella isabellina was found to be used to synthesize unsaturated fatty acids when the fungus was cultivated in a medium consisting of 2% octadecanol, 1% yeast extract and Mg 2+ with concentration at 25 mmol/L at 23 ℃ for 120 h. The harvested dry cells contained 47.5% lipids, 28.9% carbohydrate and 31.5% protein. The results showed that the lipid selectivity was 30.6%, at a yield of 20.6%. The data also indicated the selectivity of fatty acids in the lipids, was palmatioleic(0.81%), oleic(20.75%), linoleic(1.95%), linolenic(2.19%) respectively. Lowering the concentration of substrates in the medium led to increasing selectivities of both lipids and unsaturated fatty acids synthesized by the fungus, and when mass fraction of octadecanol was 0.5%, the maximal selectivities of the corresponding fatty acid were obtained. A study of initial pH of the medium suggested that the maximal selectivity and yield of lipids were obtained at a pH value of 7. The octadecanol conversion reached a maximum(88%) when cultivated at 33 ℃, however, the lipid yield reached a maximum(9.7%) at 23 ℃. Mg 2+ was found to strongly influence the productivity of lipids and unsaturated fatty acids. For instance, a concentration of 25 mmol/L of Mg 2+ in the culture broth may cause a maximal selectivity(25.7%) and yield(17.6%) of lipids.