Lipid formation in the oleaginous mould Entomophthora exitalis grown in continuous culture: effects of growth rate, temperature and dissolved oxygen tension on polyunsaturated fatty acids
1992
Kendrick, A. | Ratledge, C.
The oleaginous fungus Entomophthora exitalis was grown in continuous culture at a constant dilution rate (0.04 h-1) and over a range of temperatures (20-30 degrees C). As the growth temperature was decreased from 30 to 20 degrees C the percentage of polyunsaturated fatty acids (PUFA) increased proportionally from 18 to 27% (w/w) of the total fatty acids. The increase in unsaturation was as a result of an increased proportion of n-6 PUFA (particularly arachidonic acid) in the phospholipid and sphingo- plus glycolipid fractions. The triacylglycerol fraction of lipids displayed a negligible change. The proportion of phospholipids within the extracted lipid increased between 26 and 20 degrees C without any change in the lipid content of the fungus. Although the changes in lipid unsaturation correlated, at first inspection, to the culture dissolved O2 tension (DOT), growth of the fungus at a constant dilution rate and temperature (22 degrees C) over a range of DOT values failed to influence lipid unsaturation. Thus temperature is the principal regulation factor of the degree of unsaturation in the lipids of this organism.
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