Melatonin: Possible mechanism of commercial production by cyanobacteria for human welfare and sustainable agriculture

Melatonin (MT), a multifunctional signaling molecule is endogenously produced in different microorganisms such as bacteria, cyanobacteria, algae, fungi, and plants, animals including human beings. In addition to controlling the sleep cycle, MT has gained popularity in treating various human diseases, including cancer, COVID-19, and neurological and psychiatric disorders. It plays an important role in abiotic stress tolerance in all living beings including plants and cyanobacteria. In comparison to plants and other eukaryotes, MT is less studied in cyanobacteria. Cyanobacteria are the first photosynthetic oxygen-evolving microorganisms. They play an important role as natural biofertilizers in the agriculture fields, hence widely used for human welfare and environmental sustainability. The current review emphasizes the biosynthetic mechanisms, the function of MT in cyanobacteria under abiotic stress conditions, and the application of MT in human welfare and sustainable agriculture. A possible method for commercial production of MT with the support of a biotechnology approach where cyanobacteria can be used as a natural source has been discussed in brief.