Production of gamma-linolenic acid by the fungus Cunninghamella echinulata CCRC 31840

The effect of various carbon and nitrogen sources and carbon/nitrogen (C:N) ratios on the gamma-linolenic acid (GLA) production by Cunninghamella echinulata CCRC 31840 was examined in shake cultures. On the same weight base, soluble starch was the most preferred carbon source for the growth of this fungal strain and also yielded the largest amount of GLA per unit volume. In the lactose medium, growth of C. echinulata CCRC 31840 was very poor but the most unsaturated lipid was produced. Ammonium nitrate and urea were the better nitrogen sources for growth than potassium nitrate, ammonium chloride, and ammonium sulfate. C. echinulata CCRC 31840 grown on KNO3 acquired the richest lipid content (35.4%); however, the content of GLA in the lipid (7.9%) was much lower than that grown on urea (25.7%). An initial C:N ratio of approximately 33-48.5 favored lipid accumulation in biomass without affecting the GLA content of the lipid. A maximum GLA yield of 964 mg/L was obtained after 5 days of incubation at 20 degrees C in a medium containing 10% soluble starch, 0.5% yeast extract, 0.11% NH4NO3, 0.1% KH2PO4, and 0.025% MgSO4 . 7H(2)O.