PRODUCTION OF GAMMA-LINOLENIC ACID BY THE FUNGUS MUCOR-ROUXII ON CHEAP NITROGEN AND CARBON-SOURCES

The production of gamma-linolenic acid (GLA) by the fungus Mucor rouxii CBS 416.77 was studied on low budget nitrogen and carbon sources, i.e. rape meal, cocos expeller and two types of yeast extract (nitrogen sources), and starch, starch hydrolysate, beet molasses and cocos expeller (carbon sources). As references, Difco yeast extract and glucose were used. In flask cultivations the three yeast extracts were fully interchangeable, while the Difco yeast extract (the most expensive of those tested) gave a higher productivity of GLA in fermentor cultures (14 mg.l-1.h-1). The yield of lipids and GLA were increased in the order yeast extract < rape meal < cocos expeller. Thus the amount of lipid increased from 0.56 to 2.8 g.l-1, and that of GLA from 0.15 to 0.33 g.l-1. Use of beet molasses or cocos expeller as carbon sources gave poor growth. Starch and starch hydrolysate resulted in better productivity of GLA than glucose (4.7 and 4.9 compared to 3.4 mg.l-1.h-1).