From the first botanical characterization of cyanobacteria about two centuries ago to contemporary studies, only two categories of extracellular UV-screening pigments have been considered: scytonemin which is very well described and gloeocapsin, which remains enigmatic. In this study, we use Raman microspectroscopy to compare the extracellular EPS-associated pigment produced by the strain Chamaesiphon polonicus SAG 32.87 with gloeocapsins, scytonemins and other natural and synthetic pigments. Chemometrics analyses of Raman data reveal the existence of a third and new category of cyanobacterial extracellular pigment.
Lara et al. (Sun,) studied this question.