title: Lipid profile remodeling in response to nitrogen deprivation in the microalgae Chlorella sp. (Trebouxiophyceae) and Nannochloropsis sp. (Eustigmatophyceae).
abstract: Many species of microalgae produce greatly enhanced amounts of triacylglycerides (TAGs), the key product for biodiesel production, in response to specific environmental stresses. Improvement of TAG production by microalgae through optimization of growth regimes is of great interest. This relies on understanding microalgal lipid metabolism in relation to stress response in particular the deprivation of nutrients that can induce enhanced TAG synthesis. In this study, a detailed investigation of changes in lipid composition in Chlorella sp. and Nannochloropsis sp. in response to nitrogen deprivation (N-deprivation) was performed to provide novel mechanistic insights into the lipidome during stress. As expected, an increase in TAGs and an overall decrease in polar lipids were observed. However, while most membrane lipid classes (phosphoglycerolipids and glycolipids) were found to decrease, the non-nitrogen containing phosphatidylglycerol levels increased considerably in both algae from initially low levels. Of particular significance, it was observed that the acyl composition of TAGs in Nannochloropsis sp. remain relatively constant, whereas Chlorella sp. showed greater variability following N-deprivation. In both algae the overall fatty acid profiles of the polar lipid classes were largely unaffected by N-deprivation, suggesting a specific FA profile for each compartment is maintained to enable continued function despite considerable reductions in the amount of these lipids. The changes observed in the overall fatty acid profile were due primarily to the decrease in proportion of polar lipids to TAGs. This study provides the most detailed lipidomic information on two different microalgae with utility in biodiesel production and nutraceutical industries and proposes the mechanisms for this rearrangement. This research also highlights the usefulness of the latest MS-based approaches for microalgae lipid research.
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Gregory J O
authors.initials: GJ
authors.lastname: Martin
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: David R A
authors.initials: DR
authors.lastname: Hill
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Ian L D
authors.initials: IL
authors.lastname: Olmstead
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Amanda
authors.initials: A
authors.lastname: Bergamin
authors.affiliation: Metabolomics Australia, The School of Botany, The University of Melbourne, Parkville, Victoria, Australia; Apicolipid Group, Laboratoire Adaption et Pathogenie des Microorganismes UMR5163, CNRS, University of Grenoble I, La Tronche, France.
authors.forename: Melanie J
authors.initials: MJ
authors.lastname: Shears
authors.affiliation: Metabolomics Australia, The School of Botany, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Dias
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Sandra E
authors.initials: SE
authors.lastname: Kentish
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Scales
authors.affiliation: Apicolipid Group, Laboratoire Adaption et Pathogenie des Microorganismes UMR5163, CNRS, University of Grenoble I, La Tronche, France.
authors.forename: Cyrille Y
authors.initials: CY
authors.lastname: Botté
authors.affiliation: Metabolomics Australia, The School of Botany, The University of Melbourne, Parkville, Victoria, Australia; Centre for Chemistry and Biotechnology, School of Life and Environmental Sciences, Deakin University, Burwood, Victoria, Australia.
authors.forename: Damien L
authors.initials: DL
authors.lastname: Callahan
mesh_terms: D002708:Chlorella / Q000378:metabolism*; D050356:Lipid Metabolism; D058086:Microalgae / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*
chemical_list: D009584:Nitrogen