Identification of the carotenoid pigment canthaxanthin from photosynthetic Bradyrhizobium strains

Abstract

Canthaxanthin (4,4'-diketo-β-carotene) is produced as the major carotenoid pigment by orange- and dark-pink-pigmented bacteriochlorophyll- containing Bradyrhizobium strains isolated from stem nodules of Aeschynomene species. These two new pigmentation groups differ from the well-studied strain BTAi1, which accumulates spirilloxanthin as the sole carotenold.