Realizing the Full Potential of Lipidomics: A New Protool for an Improved Extraction of the Intact Polar Lipids of Archaea

Summary The investigation of intact polar lipids (IPLs) is a powerful tool for investigating the physiology of Archaea in cultures and their prevalence in environmental samples. IPLs are typically extracted using the Bligh and Dyer protocol. However, recent studies have exposed both, bias and a low extraction efficiency for archaeal lipids obtained by this technique. Here, we tested different solvent mixtures, mechanical rupture techniques and chemical detergents/enzymatic lysis buffers for their potential to destroy the cell envelope and thus increase the extraction efficiency of archaeal IPLs in pure cultures and environmental samples. The tests with different solvent mixtures revealed highest IPL yields when samples were extracted with a monophasic solvent system that included a trichloroacetic acid buffer. Freeze-thaw cycles prior to the extraction after Nishihara and Koga (1987) enhanced the extraction efficiency by 1.7-times, while other investigated mechanical rupture techniques (bead beating and osmotic shock) showed no increase. The use of chemical detergents in combination with freeze-thaw cycles resulted in significantly higher IPL yields than the experiments without the pre-treatment. The results demonstrate that the novel protocol results in significantly higher archaeal IPL abundances than the Bligh and Dyer protocol, suggesting that earlier studies may have overlooked the majority of IPLs.