Abstract
One of important functions of carotenoids is the protection against photooxidative damage in photosynthetic organisms. Nevertheless, the correlation between the chemical structure of carotenoids and their protective function against photooxidative damage, have been investigated insufficientry. To assess functional features of cyclic carotenoids, we attempted to construct a mutant of the purple photosynthetic bactererium, Rubrivivax gelatinosus (IL144), that accumulated lycopene, and then lycopene cyclase gene (crtY) from Erwinia uredovora was introduced into the mutant. This mutant accumulated β-carotene in cell, membrane and pigment proteins. This fact shows that the cyclic carotenoid can be used for growth of the purple bacterium that originally has only acyclic carotenoids. Resistance against singlet oxygen of the mutant strain seemed to be higher than that of the lycopene accumulating strain, although that against photodamage of the both strains were similar to each other.
