Abstract
We identified the carotenoids in the cyanobacterium, Thermosynechococcus elongatus BP-1. β-Carotene (51%, mol% of total carotenoids), β-cryptoxanthin (trace) and zeaxanthin (8%) were found. Further, caloxanthin (6%) and nostoxanthin (14%) were present. Myxol glycoside (5%) and OH-myxol glycoside (15%) were typical carotenoid glycosides in cyanobacteria. Although ketocarotenoids, such as echinone and ketomyxol glycoside, were also typical carotenoids in cyanobacteria, they were absent. Glycoside moiety of myxol glycoside is under study. Among the carotenogenesis genes, only crtE is functionally confirmed. From homology search, presence of crtB, crtP, crtQ and crtR was suggested. β-Carotene ketolase, crtO and crtW, were absent. A homologous gene crtG of β-carotene 2-hydroxylase, which produces nostoxanthin from zeaxanthin, was found, and its function is under study. The biosynthetic pathway of carotenoids will be discussed. (Takaichi, Mochimaru (2007) Carotenoids and carotenogenesis in cyanobacteria: unique ketocarotenoids and carotneoid glycosides, Cell. Mol. Life Sci. 64: 2607-2619)
