Converting octadecanol to unsaturated fatty acids catalyzed by Mortierellaisbellina

Mortierella isabellina was found to be used to synthesize unsaturated fatty acids when the fungus was cultivated in a medium consisting of 2 % octadec anol, 1 % yeast extract and Mg2+ with concentration at 25 mmol/L at 23 degr eesC for 120 h. The harvested dry cells contained 47.5% lipids, 28.9% carbo hydrate and 31.5% protein, The results showed that the lipid selectivity wa s 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 %), lino leic (1.95%), linolenic (2.19 %) respectively. Lowering the concentration o f substrates in the medium led to increasing selectivities of both lipids a nd unsaturated fatty acids synthesized by the fungus, and when, mass fracti on of octadecanol was 0.5 %, the maximal selectivities of the corresponding fatty acid were obtained. A study of initial pH of the medium suggested th at 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 degreesC, however, the lipid yield reached a maximum (9.7 %) at 23 degr eesC. Mg2+ was found to strongly influence the productivity of lipids and u nsaturated fatty acids. For instance, a concentration of 25 mmol/L of Mg2in the culture broth may cause a maximal selectivity (25.7 %) and yield(17. 6%) Of lipids.