Hydrocarbons, sterols, esters and fatty acids in six freshwater chlorophytes

Hydrocarbons, alkyl esters, free sterols and fatty acids were identified in five cultured and one natural species of freshwater chlorophytes. Monoenoic hydrocarbons occurred in four species, two of which also contained the n-C 17 alkane; two desmid species contained only polyenes. All species contained alkyl and phytyl esters in the C 3O–C 38 range. The sterol composition differed considerably between species, but was broadly consistent with the respective taxonomic position of each organism. In particular, the sterols of two desmid species were consistent with the accepted position of their parent order on the evolutionary pathway leading to vascular plants. The fatty acids consisted mainly of n3 polyenoic and 16:0 acids throughout; only Ulothrix contained acids having more than 18 carbon atoms.