Maximizing the production of gamma-linolenic acid in Mortierella ramanniana var. ramanniana as a function of pH, temperature and carbon source, nitrogen source, metal ions and oil supplementation

A locally isolated (Perryvale, Alta., Canada) fungal genus, Mortierella ramanniana var. ramanniana, was evaluated as a potential industrial producer of gamma-linolenic acid (GLA). Six growth variables (pH, temperature, carbon source, nitrogen source, and metal ions and oil supplementation) were systematically manipulated. The results indicated that the GLA production for this particular strain, could be maximized by using a basal growth medium consisting of 5% dextrose and 1% yeast extract, supplemented with 5 mg/L Mn2+ with incubation at 20 degrees C. The lipid yield under optimum conditions was 54.2% of the total dry biomass and consisted of 84.3% unsaturated fatty acids. The yield of GLA per gram biomass represented 13.3% of the total lipid content, slightly higher than that of the typical evening primrose oil GLA yield. The study establishes this variety as an effective intermediate fungal source of GLA. (c) 2005 Elsevier Ltd. All rights reserved.