Mangrove cyanobacterial diversity as a source of bioactive natural products

• First global review linking polyphasic taxonomy to cyanobacterial metabolites in mangroves • Catalogs cyanobacterial strains recognized only by modern morphological and molecular data • Reveals high cyanobacterial diversity across mangrove ecosystem, including novel taxa • Highlights diverse bioactivities: antimicrobial, anticancer, toxins, bioplastic • Bridges taxonomy with biotech applications in drugs, agrochemicals, dyes, biofuels Extensive exploration of lesser-explored habitats undertaken in search of novel and sustainable sources of pharmaceuticals, agrochemicals, renewable energy sources, and dyestuffs has uncovered the capability of cyanobacteria or blue-green algae as producers of these commodities. Mangroves represent one such highly abiotic-stressed and vulnerable biodiversity hotspot found in the intertidal regions of the tropics and sub-tropics that harbor diverse microflora. However, limited data on cyanobacterial taxonomic classification and the study of secondary metabolites rich in novel molecules is currently available, as compared to other prokaryotes. The discovery of useful natural products from cyanobacteria is limited since few strains can be genetically modified and beneficial compounds are often produced in low or inconsistent amounts. Difficulties with transferring biosynthetic pathways to other hosts, combined with the high cost and ecological challenges of scaling cultivation and advanced screening, require integrated multiomics and simple, scalable workflows for industrial translation. This article attempts to review the reported bioactive secondary metabolites of importance produced by cyanobacteria from mangrove ecosystems across the world and the modern methods that can be utilized for bioactive compound discovery from these cyanobacteria.