Genomic insights into the antarctic cyanobacterium Nostoc sp. CALU 1950.

Heterocystous filamentous cyanobacteria of the genus Nostoc are vital primary producers of bioavailable nitrogen and carbon across diverse ecosystems. Here, we present the genomic and morphological characterization of Nostoc sp. CALU 1950, isolated from an Antarctic littoral mat. Phylogenetic analysis firmly places strain CALU 1950 within the Nostoc sensu stricto clade, sharing the highest genetic identity with Nostoc edaphicum CCNP1411. The 8.76 Mb draft genome contains 7463 protein-coding genes, with 2400 functionally annotated by KEGG. Genomic mining revealed a diverse array of biosynthetic gene clusters (BGCs) involved in secondary metabolism, primarily driven by non-ribosomal peptide synthase (NRPS) and polyketide synthase (PKS) pathways. The high structural synteny of cyanopeptolin (CP) and anabaenopeptin (AP) clusters to reference strains underscores the genetic stability of these strain within the lineage.