Involved in the biosynthesis of the yellow-orange carotenoid staphyloxanthin, which plays a role in the virulence via its protective function against oxidative stress. Catalyzes three successive dehydrogenation reactions that lead to the introduction of three double bonds into 4,4'-diapophytoene (dehydrosqualene), with 4,4'-diapophytofluene and 4,4'-diapo-zeta-carotene as intermediates, and 4,4'-diaponeurosporene (the major deep-yellow pigment in staphylococci strains) as the end product. 15-cis-4,4'-diapophytoene + 3 FAD + 3 H(+) = all-trans-4,4'-diaponeurosporene + 3 FADH2 Carotenoid biosynthesis; staphyloxanthin biosynthesis; staphyloxanthin from farnesyl diphosphate: step 2/5. Belongs to the carotenoid/retinoid oxidoreductase family. CrtN subfamily.