Metabolomic and taxonomic characterization of Haloleptolyngbya lusitanica sp. nov . (Cyanobacteria, Synechococcales)

The morphological plasticity of cyanobacteria and their widespread ecological dominance in a wide range of habitats highlights the need for in-depth taxonomic studies. This work focused on the taxonomical revision of Leptolyngbya (Cyanophyceae) strains deposited in the ESSACC culture collection and their metabolomic characterization. Although the studied ESSACC strains were morphologically identified as Leptolyngbya sp., the 16S rRNA gene and 16S–23S rRNA ITS analysis revealed that two strains (LMECYA 079 and LMECYA 173) belong to Haloleptolyngbya and represent a new taxonomical unit, genetically unique, ecologically plastic and adapted to both freshwater and thermal habitats, here described as Haloleptolyngbya lusitanica sp. nov. To perform a suspect screening of cyanometabolites in these strains, we used a non-targeted liquid chromatography-high resolution mass spectrometry (LC-HRMS) metabolomic approach. Several metabolites were identified in Haloleptolyngbya lusitanica: micropeptin MM978, spumigin 640, oscillatoxin A and anabaenopeptin D. Strains were maintained and grown under the same conditions, revealing the common production of oscillatoxin A by both H. lusitanica strains. Other identified metabolites, however, were strain-specific, such as anabaenoptin D, which was only detected in LMECYA 173. The different cyanometabolite profiles reinforce the notion that cyanobacteria have the ability to adapt to different habitats, which is maintained under long-term culturing conditions.