Requires FAD. The enzyme is involved in carotenoid biosynthesis and catalyses up to four desaturation steps (cf. EC 1.3.99.28 [phytoene desaturase (neurosporene-forming)], EC 1.3.99.29 [phytoene desaturase (¦Æ-carotene-forming)] and EC 1.3.99.30 [phytoene desaturase (3,4-didehydrolycopene-forming)]).