Description of a New Marine Cyanobacterium from the Cabo Verde Archipelago: Pigments Profile and Biotechnological Potential of Salileptolyngbya caboverdiana sp. nov.

Cyanobacteria are prolific producers of specialized metabolites of growing interest for blue biotechnology, transversal to various sectors such as cosmetics, foods and pharmaceuticals. In this work, the marine cyanobacterial strain <i>Salileptolyngbya</i> sp. LEGE 181209, from Cabo Verde, was systematically characterized to resolve its taxonomy, pigments profile, and cytotoxicity assessment. A polyphasic workflow combining 16S rRNA gene phylogenies, 16S-23S ITS secondary structures, <i>p</i>-distance, morphology, and scanning electron microscopy (SEM) was used to establish the taxonomic placement of the strain as a new species of the genus. PCR assays targeting the toxin biosynthetic genes <i>mcyA</i> and <i>anaC</i>, and cytotoxicity assays in HaCaT keratinocytes showed low-to-absent cytotoxicity, supporting a safety-forward profile for downstream use. A sequential extraction with solvents of different polarities yielded complementary pigment fractions profiled by HPLC-PDA and spectrophotometry. Total carotenoids reached 72.7 µg mg^-1 of dry extract (DE), the profile being dominated by β-carotene and zeaxanthin (≈42 and 8 µg mg^-1 of DE, respectively); chlorophyll-<i>a</i> was also very representative, reaching 85.6 µg mg^-1 of DE. Phycobiliproteins dominated the polar fraction, with phycocyanin reaching 150 µg mg^-1, followed by sugars (19.7 µg of glucose equivalents mg^-1) and phenols (8.8 µg of gallic acid equivalents mg^-1).