Capturing Light and the Diversity of Pigments

The role of photosynthetic pigments is to harvest light, that is, to acquire the energy of a photon and ultimately transfer that energy into useful biochemical energy. Evolution has led to a vast array of pigment types and combinations that confer different light-absorbing efficiencies and spectral sensitivities that are optimum under specific natural light regimes. Despite the vast array of colors, the pigments that participate in photosynthesis originate from only three molecular classes of compounds, chlorophylls, carotenoids/xanthophylls, and phycobilins. This chapter reviews the structure of these pigment groups, as well as their absorption properties. The diagnostic pigment signature of different algal classes is also introduced. Lastly, this chapter introduces the concept that algal pigments have applications beyond photochemistry; their structures and composition are of interest because they serve as pharmaceuticals, synthetic food colorants, dietary supplements, and are also used in cosmetics, aquaculture, textiles, and other light manufacturing fields.