Advancements and Trends in Omics of Cyanobacterial Ultraviolet-Screening Compounds, Scytonemin and Mycosporine-Like Amino Acids

Cyanobacteria, on exposure to ultraviolet radiations (UVR), synthesize UV-absorbing compounds such as scytonemin and mycosporine-like amino acids (MAAs) to mitigate their harmful effects. Only a few cyanobacteria are capable of synthesizing scytonemin, an extracellular polysaccharide sheath pigment. It is a lipophilic pigment that consists of phenolic and indolic monomer components connected by an olefinic carbon atom. In MAAs, the nitrogen moiety of an amino acid or its amino alcohol is coupled with an aminocyclohexinimine or aminocyclohexenone chrompohore. These are small, colorless, hydrophilic molecules. These compounds have strong antioxidative potential, are photostable, and are effective photoprotectants. The complex stress response pathway and environmental signals that contribute to the synthesis and induction of these secondary metabolites are poorly understood, despite the fact that a great deal of work has been invested in the past ten years to bio-prospect and describe them. Cyanobacterial molecular biology has greatly benefited from the application of “omics” approaches. Although targeted metabolome approaches only measure small groups of metabolites, metabolomics research provides an investigative tool for the quick exploration, discovery, and characterization of secondary metabolites produced by an organism. Metabolomics has emerged as a key technique in synthetic biology for identifying new molecules from microorganisms, such as cyanobacteria. Additionally, it makes it possible to manufacture whole sets of metabolites or their precursors with the appropriate titers. This chapter discusses developments made in the field of metabolomics of cyanobacterial ultraviolet-screening compounds, scytonemin, and MAAs in detail.