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Abstract
Saccharomyces cerevisiae grew at the same rate aerobically in a glucose/salts medium as anaerobically in a defined medium supplemented with ergosterol and either oleic, linoleic or α-linolenic acid. However, exponential growth extended for a longer time in aerobic cultures. Irrespective of the nature of the fatty acid provided, phosphatidylcholine from anaerobically grown organisms harvested from early mid-exponential phase cultures contained a higher proportion of residues chemically identical with that provided in the medium compared with the phospholipid from organisms harvested at later stages of batch growth. The fatty-acyl composition of phosphatidylethanolamine and of a fraction containing phosphatidylinositol and phosphatidylserine showed similar changes to those found in phosphatidylcholine. Similar trends were also detected in the fatty-acyl composition of triacylglycerols from organisms grown anaerobically in the presence of different fatty acids and harvested at different stages of growth. However, at all stages of growth there was a higher percentage incorporation of the exogenously provided acid into triacylglycerols. The fatty-acyl composition of individual classes of phospholipid and of triacylglycerols from aerobically grown organisms remained remarkably constant throughout growth in batch culture. There were, however, characteristic differences in the fatty-acyl composition of different classes of lipid.
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