Sterols, aliphatic hydrocarbons, and fatty acids of a nonphotosynthetic diatom,Nitzschia alba

The unsaponifiable lipids and total fatty acids of a nonphotosynthetic diatom, Nitzschia alba , have been examined. The major fatty acids were found to be 14∶0, 16∶0, 18∶1, and 20∶5; small amounts of 15∶0, 16∶1, 18∶0, 18∶2, 18∶3, and 20∶4 acids also were present. The unsaponifiable lipids consisted mostly of sterols, with only traces (<0.1%) of hydrocarbons (chiefly C 16 , C 18 , and C 28 normal olefins). The sterols contained brassicasterol (major) and clionasterol (minor), as well as traces of an unidentified sterol; clionasterol was present only in glycosidically bound form.