Biochemical Changes During the Growth of Fungi II. Ergosterol and Fatty Acids in Penicillium atrovenetum

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Abstract
Changes in the lipid constituents of Penicillium atrovenetum were studied during the growth and development of this fungus. The stages in development, as measured by the dry weight, were divided into four phases: lag, log, stationary, and death. The total fatty acids on a dry-weight basis increased from a minimum in the spores to a maximum near the end of the log phase of growth. The major fatty acids were palmitic, stearic, oleic, and linoleic. Myristic, pentadecanoic, palmitoleic, heptadecanoic, linolenic, arachidic, and heptadecenoic acids, together with two unidentified components, were also present in the fatty acid fraction. Compared to ungerminated spores, young mycelium contained a much lower percentage (on the basis of total fatty acids) of linoleic acid. There was a corresponding increase of oleic acid. Except for palmitic acid, which remained constant, the remaining fatty acids increased slightly. During subsequent growth of the fungus, linoleic acid decreased, whereas the percentage of palmitic and stearic acids increased steadily from the lag phase to the end of the log phase. Ergosterol was the only sterol detected. The percentage of ergosterol, on a dry-weight basis, increased to a maximum at the start of the log phase and then steadily decreased. The following changes in lipids appear to be associated with the development and aging of fungi: (i) the presence of a relatively high content of nonsaponifiable lipid and ergosterol in the young mycelium, and their later decrease with age, and (ii) a shift from more unsaturated to less unsaturated fatty acids with age.