Sterols and fatty acids in foams from Antarctic lakes of the Dry Valleys in south Victoria Land

Sterols and fatty acids were studied for foam samples from lakes of Wright Valley in the Dry Valleys of south Victoria Land, Antarctica. Sterols, cholesta-5, 22-dien-3β-ol, cholest-5-en-3β-ol, 24-methylcholesta-5, 22-dien-3β-ol, 24-methylcholest-5-en-3β-ol, 24-ethylchlesta-5, 22-dien-3β-ol, 24-ethylcholest-5-en-3β-ol and 5α-cholestan-3β-ol, and fatty acids ranging from C10 to C28, including n-alkanoic, branched (iso and anteiso) and unsaturated acids were found in the foam samples. The dominant sterol was cholest5-en-3β-ol or 24-ethylcholest-5-en-3β-ol. The sterol and fatty acid compositions of the foam samples are similar to those of epibenthic organisms (mainly cyanobacteria). The sources of the sterols and fatty acids are most likely cyanobacteria. In addition, these lipid components were concentrated considerably in the foams.