Quantity and fatty acid composition of lipid extracted from cells of Streptococcus lactis.

MacLeod, Patricia (University of Connecticut, Storrs), R. G. Jensen, G. W. Gander, and J. Sampugna. Quantity and fatty acid composition of lipid extracted from cells of Streptococcus lactis. J. Bacteriol. 83:806-810. 1962.-A method for the extraction of lipid from bacterial cells is described. Lysozyme-treated cells of Streptococcus lactis yielded 5% of their dry weight as lipid, whereas cells not treated with lysozyme yielded only 3% lipid. More than two-thirds of the bacterial lipid extracted was tentatively classified as phospholipid, based on the elution behavior of this fraction on silicic acid columns when chloroform and methanol were the eluting solvents. The following five major fatty acids were present in all lipid fractions isolated: myristic, palmitic, palmitoleic, lactobacillic, and an 18-carbon acid possessing one double bond, which may actually be oleic acid or a mixture of oleic and one or more of its isomers. These acids comprised more than 85% of the acids found, as indicated by gas-liquid chromatography of their methyl esters. Since lactobacillic acid accounted for about 20% of the fatty acids extracted from cells of S. lactis, this organism may prove to be a ready source of this comparatively rare acid.