LC-MS characterization of pigments in microalgae from different cultivation regimes

Abstract

<p>Background: The Artic University of Norway entered a partnership with a smelting plant to reduce the factory fume CO2-footprint by cultivation of microalgae (diatoms). The biomass produced from the microalgae is rich in lipids, proteins and pigments and can potentially function as fish feed for the aquaculture industry. Before the biomass can be utilized as e.g. fish feed, a thorough investigation of its constituents is important. In this thesis the main goals were to characterize the pigment composition in <i>Porosira glacialis</i> and investigate if different light regimes could affect the pigment composition. <p>Method: The microalgae, <i>Porosira glacialis</i>, cultivated in red, blue and white light regimes was included in the project. From freeze-dried algal biomass, the pigments were extracted with a mixture of methanol and acetone. Two different LC-MS techniques were investigated (Q-orbitrap and Q-TOF) for analyzing extracted pigments. Liquid chromatography coupled to Q Exactive with ESI in full scan mode was applied. A MS/MS mode was used to determine the fragmentation pattern of chlorophyll a and astaxanthin as well as identification of other pigments. <p>Results: Twelve pigments could be detected and identified in <i>P. glacialis</i>, where seven of them are carotenoids. The results suggest that light regimes can regulate the accumulation of different pigments in <i>P. glacialis</i>, especially carotene. The best light regime for accumulating chlorophyll a was white light. <p>Conclusion: The white light regime seems promising in cultivation of the microalgae, <i>P. glacialis</i>, in regards to the amount of pigments. It is however possible to induce a change in relative pigment composition by changing the color of the light during cultivation.