Abstract
As a n-6 essential fatty acid, γ-linolenic acid (GLA) has been shown to be more effective than linoleic acid. Its effects cover anti-atherosclerosis including hypocholesterolic and anti-thrombogenic effect, anti-cancer, higher alcohol oxidation, anti-inflammatory effect and others. These effects are generally attributed to by-passing Δ6-desaturase reaction.
Using some species in genus Mortierella, lipid accumulative fungi, attempt at increase in lipid and GLA productivity has been made changing carbon and nitrogen source, pH, temperature and others. Decane as carbon source resulted in higher polar lipid content in spite of lower growth than glucose. Cultivation at higher glucose concentration (>100 g/L), originally intended to get higher cell mass per unit volume of culture medium, resulted in higher lipid content. The optimum culture conditions for lipid accumulation were lower both in pH and temperature than those for growth, which lead to our proposal of 2 tanks continuous system to separate growth from lipid accumulation phase. The maximum lipid productivity of 1.1 g/L·h and GLA productivity of 106 mg/L·h were obtained in a continuous operation at 0.15-1 of dilution rate and 100 g/L of feed glucose concentration.
