The Core Lipid Composition of the 17 Strains of Hyperthermophilic Archaea, Thermococcales

Abstract

The core lipid compositions of the strains of the genus Pyrococcus (3 strains), Thermococcus (13 strains) and Palaeococcus (1 strain) belonging to the Order Thermococcales, Euryarchaeota were examined. In the 85°C culture, the main core lipid of every strain was caldarchaeol (dibiphytanyldiglycerol tetraether). No cyclopentane rings were detected in the C₄₀ isoprenoid chains of caldarchaeol from any of the tested strains. Archaeol (diphytanylglycerol diether) was also detected in these strains, and the contents were 5.9% to 42.1% for the total core lipids. The H-type caldarchaeol in which two isoprenoid chains were linked to each other by a covalent bond around the center of both isoprenoid chains was detected in 4 strains, with no relationship to the classification of the genera. The profile of the core lipids in these strains showed that the core lipid composition of Thermococcales is close to that of the thermophilic methanogen in Euryarchaeota.