Analytical method for the differentiation of C25C20 diether lipid core isomer characteristic for h

Abstract

Halophilic Archaea produce a C₂₅C₂₀ diether as a core lipid with one C₂₅ isoprenoid, and this compound could be used as an indicator of high salinity environments. On the other hand, two regioisomer of C₂₅C₂₀ diether are existed structurally, but different isomers are reported to exist in biological and rock-salt samples. I developed a method to show the presence of two isomers by characteristic fragments of the mass spectra with chemically synthesized standard. The results of recent study showed that a certain micro-organism have two isomers in the biological sample and a small amount of isomers in the rock-salt sample. For the quantitative analysis of the two isomers which is independent with the comparison of intensity of the fragment ions, a quantitative analysis through the regiospecific degradation of the ether was investigated.Currently, trace amounts of rock-salt isomers appear to be the result of minor fragmentation in mass spectrometry, confirming previously reported results of most microorganisms. However, this method is also applicable to the differentiation of positional isomers of asymmetric diether lipids in bacteria.