Fatty Acid and Sterol Composition of Mucor genevensis in Relation to Dimorphism and Anaerobic Growth

Abstract

Fatty acid and sterol content and composition were determined for the dimorphic mold, Mucor genevensis, grown under a variety of experimental conditions. Fatty acids account for 6 to 9% of the dry weight of aerobically grown mycelium, and 70 to 80% of these are unsaturated. The organism contains 'y-linolenic acid which is characteristic for Phycomycetes, and in sporangiospores this compound represents 40% of the total fatty acids. Of the sterols found in mycelium, 80% is ergosterol, and stigmasterol was positively identified as one of the minor components. In anaerobically grown yeastlike cells, sterol content is less than 10% of the level found in aerobically grown cells, and fatty acids amount to less than 2% of the dry weight. These fatty acids are predominantly short chain and less than 10% are unsaturated. Yeastlike cells obtained under aerobic conditions by growth in the presence of phenethyl alcohol have fatty acid and sterol compositions characteristic of aerobically grown mycelium. It is concluded that the dimorphology of the organism is not directly related to lipid composition.

Lipid Composition of the Zoospores of Blastocladiella emersonii

“…Although the quantity of sterols and SE in the zoospores of B. emersonii seems to exceed the amount in most other Phycomycetes (42), the fatty acid composition of the B. emersonii zoospores does resemble that of other terrestrial phycomycetes (2,7,14,33,39). In addition, 'y-linolenic acid-once thought (33) to be both characteristic of and limited to the phycomycetes, but recently found (32) to occur in other fungi-was associated predominantly with polar lipids in the zoospores we analyzed, as it was in the mixture of variously aged thalli harvested from multiple generation B. emersonii cultures by Sumner (38).…”

Effects of Oxygen and Glucose on Energy Metabolism and Dimorphism of Mucor genevensis Grown in Continuous Culture: Reversibility of Yeast-Mycelium Conversion

“…M. genevensis NRRL 1407 was maintained on cornmeal agar slopes (Difco Emerson's media) at 12 or 4 C and transferred every 8 weeks. Spores were harvested from these slopes as described previously (14).…”

“…Extraction of fatty acids and sterols. The procedures used were those described by Gordon, Stewart, and Clark-Walker (14).…”

“…Among species of fungi which are dimorphic, the genus Mucor has attracted considerable attention. It is known that for some species of this genus culture conditions which favor fermentation also promote yeast-like morphology, whereas oxidative conditions promote mycelial development (5,9,14,23,24).To gain a better insight into the molecular processes underlying the transformation from yeast-like to mycelial forms, a more precise understanding of the transition from fermentative to oxidative metabolism is required. Furthermore, a knowledge of the extent to which…”

“…Among species of fungi which are dimorphic, the genus Mucor has attracted considerable attention. It is known that for some species of this genus culture conditions which favor fermentation also promote yeast-like morphology, whereas oxidative conditions promote mycelial development (5,9,14,23,24).…”