engleski

Effect of hyposalinity on polar lipid remodeling in microalga Dunaliella tertiolecta (Chlorophyceae)

Microalgae are responsible for nearly half of the world’s primary production and for most of the organic matter flux to deep waters and sediments and to higher trophic levels. They are the main source of essential polyunsaturated fatty acids for higher trophic levels in the aquatic environment. Microalgae play a critical role in aquatic ecosystem functioning, often being the major primary source of organic carbon and lipids (fatty acids). Lipids are useful biogeochemical traces of the origin and processing of organic matter. Salinity fluctuation in coastal regions such as estuaries and rock pools is one of the major abiotic stressors for microalgae. To survive, microalgae have evolved a variety of mechanisms to cope with fluctuating salinity, including accumulation and remodeling of lipids. The marine green microalga Dunaliella tertiolecta is found in a wide salinity range of waters and is often exposed to hypoosmotic stress in its usual habitat. The objective of this research was to investigate the acclimation of D. tertiolecta to salinity decrease by analyzing changes in membrane lipid composition. The microalga D. tertiolecta was exposed to growth at an optimal salinity of 38 PSU and under hyposaline conditions of 20 and 3 PSU. Hydrophilic interaction liquid chromatography coupled with electrospray ionization mass spectrometry was used to identify and quantify polar lipid classes and their fatty acid composition, while total cellular lipids were quantified by thin-layer chromatography coupled with flame-ionization detection. We found that D. tertiolecta acclimates to growth under hypoosmotic conditions (3 PSU) with a significant retardation of growth and reproduction and accumulates cellular lipids, as well as remodeling polar lipid classes and fatty acid composition. The details of cultivation and the main lipid remodeling responses will be discussed.

hyposalinity ; polar lipid ; remodeling ; Dunaliella tertiolecta

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