Extraction and separation of cyanobacterial photosynthetic and photoprotective pigments: comparison of practical and accessible methodologies

Cyanobacterial pigments are complex mixtures of water-soluble and lipophilic compounds with diverse properties and biological roles. There is a growing interest in investigating these pigments due to their potential applications in biotechnology, food production and various industrial sectors. Additionally, they serve as important markers in ecological studies, phylogenetic analyses and ecotoxicology research. Low-pressure liquid chromatography (LPLC), thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) are commonly used laboratory techniques for the fractionation and separation of pigments, with spectrophotometry being the preferred detection method. However, to date, no single study has combined all these techniques for the comprehensive analysis of cyanobacterial photosynthetic pigments. This paper presents the application of these accessible and straightforward techniques for the separation and characterization of cyanobacterial lipophilic pigments. The extraction was performed on two unicellular species, Synechocystis salina and Microcystis aeruginosa, and three filamentous cyanobacteria, Aphanizomenon flos-aquae, Nodularia spumigena and Anabaena cylindrica. The study highlights the capabilities and limitations of spectrophotometric detection of carotenoids and chlorophylls in in vivo cultures and extracts, as well as the challenges related to chlorophyll stability. Experimental work is supplemented with relevant literature and provides practical guidance on the use and interpretation of results from widely available techniques, making it a valuable resource for researchers across various fields.