Marit Huizera, Kim van Wezel,b, Kine Østnes Hansen,a, Espen Holst Hansen,b, Terje Vasskog,a
a Natural Products and Medicinal Chemistry Research Group, Department of Pharmacy, UiT the Arctic University of
Norway
b Marbio, Faculty for Fisheries, Biosciences and Economy, UiT the Arctic University of Norway
Email: marit.huizer@uit.no
Microalgae are increasingly recognised as promising sources of bioactive metabolites, yet their chemical profiles are shaped by environmental conditions. In our recent work on Arctic diatoms, we identified two antibiofilm metabolites in Porosira glacialis. We found one fatty acid methyl ester (FAME) and a chlorophyll degradation product. We also observed that the bioactivity of Cylindrotheca closterium varied depending on the cultivation conditions. These findings suggested that both lipid and pigment metabolism may shift under different cultivation regimes and that understanding these trends require an analytical approach capable of capturing both classes.
To adress this, we developed an LC-MS method on a C30 column combining polarity-switching full-scan acquisition with separate identification runs. Full-scan data was collected with rapid polarity switching. The effective MS¹ scan interval was 1.36 seconds, providing enough scans per peak for reliable relative quantification of lipids and pigments. MS² and MS³ spectra were acquired in single-polarity runs performed separately in positive and negative ionisation mode. These identification runs provided broader precursor coverage and more comprehensive fragmentation of both lipids as well as pigments and their degradation products. Data analysis was carried out in LipidSearch for lipid identification and in Compound Discoverer using an in-house pigment library for pigment annotation.
This integrated workflow enables dual-class metabolite profiling within a single chromatographic platform and supports systematic evaluation of lipid and pigment trends in continuous microalgal cultivation.