Lipidomic analysis of the extremophilic red alga Galdieria sulphuraria in response to changes in pH

Abstract

Analysis of polar lipids from the red micro-alga Galdieria sulphuraria by means of the HILIC-LC/high resolution ESI-tandem MS determined 14 classes of lipids including identification of tens of molecular species of lipids and their regioisomers. The extremophilic alga G. sulphuraria uses several mechanisms for adaptation to low pH and high temperature, the major change being a replacement of cellular phospholipids by betaine lipids. We also found a change in the ratio of regioisomers of the polar lipids, i.e. phospho-, glyco- and betaine lipids, in dependence on the culture medium pH. We hypothesize that biosynthesis of polar lipids via the prokaryotic and/or eukaryotic pathway is dependent on ambient pH.