The effect of environment on the free and hydrosoluble sterols of Mucor rouxii

Examination of the sterols produced by Mucor rouxii showed significant variations in the relative amounts of free (i.e. lipid extractable) and bound sterols contained in the aerobic and anaerobic cells. The filamentous aerobic cells contained primarily free sterols with only small amounts of the bound material. The reverse situation was true for the yeast-like anaerobic cells in which over 75% of the total sterols were bound and were released only after treatment with methanolic KOH solution. Extensive examination of the sterol fractions revealed a number of different sterols present; in the aerobic cells ergosterol was the main sterol (approx. 85 %) but in the anaerobic cells (i.e. oxygen limiting) the concentration of this component was considerable diminished (36.5%) with increased amounts of ergosta-5,7,24(28)-trien-3β-ol (37.0%), ergosta-5,7-dien-3β-ol and ergosta-7,22,24(28)-trien-3β-ol present. It was concluded that the sterol variation in the aerobic and anaerobic cells was due at least in part to both the differences in the cell growth environment which in turn were also accompanied by changes in cell morphology.