Involved in the biosynthesis of chlorobactene, a carotenoid with aromatic end group (PubMed:15292122). Catalyzes the introduction of two additional double bonds into the ionone ring of gamma-carotene to produce chlorobactene. The reaction includes an intramolecular methyl transfer from position C1 to position C2 of the ring (Probable). 2 A + a carotenoid beta-end derivative = a carotenoid phi-end derivative + 2 AH2 Binds 1 [2Fe-2S] cluster per subunit. Carotenoid biosynthesis. Mutant lacks chlorobactene and all its derivatives, and accumulates only gamma-carotene and its derivatives. The growth rate of the mutant shows no significant deviation from the wild-type growth rate at any light intensity. Belongs to the carotenoid/retinoid oxidoreductase family.