Differences in betaine lipids and fatty acids between Pseudoisochrysis paradoxa VLP and Diacronema vlkianum VLP isolates (Haptophyta)

The Haptophytes Pseudoisochrysis paradoxa and Diacronema vlkianum contained betaine lipids (DGTS, DGTA and DGCC) and phospahtidilglycerol was the only phospholipid. Differences in betaine lipids and fatty acids between both microalgae were associated to their taxonomic position. D. vlkianum is the first microalgae demonstrated to have three types of betaine lipid. •Lipid patterns of two Haptophytes associated to family taxonomic clades.•Diacronema vlkianum is first microalgae shown to have three different betaine lipids.•Pseudoisochrysis paradoxa has DGTS and DGCC but lacks DGTA.•Different molecular species of betaine lipids in two Haptophyte isolates.•Phosphatidilglycerol is the only phospholipid in two new Haptophyte isolates. Two Haptophytes were isolated from extensive aquaculture ponds at Veta La Palma state (Guadalquivir estuary, SW Spain). They were identified as Pseudoisochrysis paradoxa VLP and Diacronema vlkianum VLP based on their SSU rDNA homology to other Haptophytes and positioned in the Isochrysidaceae and Pavlovaceae families, respectively. Both Haptophytes had phosphatidilglycerol (PG) as the only phospholipid (PL), representing a low proportion of the total lipid content (0.8% in P. paradoxa VLP and 3.3% in D. vlkianum VLP). Instead, they were found to have different types of betaine lipids (BL) that were identified and characterized by HPLC/ESI-TOF-MS operating in multiple reacting monitoring (MRM) modes. P. paradoxa VLP had 2.2% of total lipids as diacylgyceryl-N-trimethylhomoserine (DGTS): it is the first Haptophyte reported to have this BL. Its total lipid fraction also contained 12.0% of diacylglyceryl-carboxyhydroxymethylcholine (DGCC) as the main BL and no diacylglyceryl-hydroxymethyl-N,N,N-trimethyl-β-alanine (DGTA) was detected. DGTA was only present (4.6% of total lipids) in D. vlkianum VLP: this was the main difference in BL content relative to P. paradoxa. D. vlkianum VLP also had DGTS (4.1%) and DGCC (7.6%): it is the first microalgae in which the simultaneous presence of these three BL has been demonstrated. The fatty acid profiles of P. paradoxa VLP and D. vlkianum VLP were close to those described for the major part of known members of the Isochrisidaceae and Pavlovaceae families, respectively, with the main differences due to the higher percentages of 18:1n9 (18.5%), 18:4n3 (12.6%) and 22:6n3 (9.3%) in the former. The corresponding fatty acid percentages for D. vlkianum VLP were 3.9%, 3.5% and 3.9%, respectively. D. vlkia