Carotenoids are naturally occurring lipid-soluble pigments, the
majority being C40 terpenoids. They act as membrane-protective
antioxidants that efficiently scavenge 1O2 and peroxyl radicals;
the antioxidant efficiency is apparently related to their structure.
Carotenoid pigments occur universally in photosynthetic systems
of higher plants, algae and phototrophic bacteria. In nonphotosynthetic
organisms, carotenoids are important in protecting
against photo-oxidative damage. Thus, many non-phototrophic
bacteria and fungi rely on carotenoids for protection when growing
in light and air (Britton et al., 1998).