J. Lorquin et al., IDENTIFICATION OF THE CAROTENOID PIGMENT CANTHAXANTHIN FROM PHOTOSYNTHETIC BRADYRHIZOBIUM STRAINS, Applied and environmental microbiology, 63(3), 1997, pp. 1151-1154
Canthaxanthin (4,4'-diketo-beta-carotene) is produced as the major car
otenoid pigment by orange- and dark-pink-pigmented bacteriochlorophyll
-containing Bradyrhizobium strains isolated from stem nodules of Aesch
ynomene species. These two new pigmentation groups differ from the wel
l-studied strain BTAi1, which accumulates spirilloxanthin as the sole
carotenoid.