Lipid and Fatty Acid Compositions of the Cytoplasmic and Thylakoid Membranes from the Thermophilic Cyanobacterium Synechococcus elongatus

Abstract

The cytoplasmic membranes (CM) and thylakoid membranes (TM) were isolated from the thermophilic cyanobacterium Synechococcus elongatus. These membranes contained similar rates of polarlipid classes; monogalactosyldiacylglycerol (MGDG) (ca. 58 %), digalactosyldiacylglycerol (DGDG) (ca. 16 %), sulfoquinovosyldiacylglycerol (SQDG) (ca. 11 %) and phosphatidylglycerol (PG) (ca. 8 %). In either membranes, about 50 % of the total lipid consisted of pigments, of which about two thirds was chlorophyll-a in TM, while in CM chlorophyll-a was at a trace amount. The remains of the pigmentswere supposed to be carotenoids in either membranes. Of the fatty acids of the lipids in either membranes, palmitic acid (16 : 0) comprised more than 50 %, oleic acid (18 : 1) about 20 %, cis-9-hexadecenoic acid (palmitoleic acid; 16 : 1) about 15 %, stearic acid (18 : 0) about 10 %. Comparing with mesophilic cyanobacteria, the Synechococcus membranes contained more pigments, less PG and more saturated fatty acids, and showed simpler profiles of fatty acid compositions.