The enzyme is involved in carotenoid biosynthesis and catalyses up to two desaturation steps (cf. EC 1.3.99.28 [phytoene desaturase (neurosporene-forming)], EC 1.3.99.30 [phytoene desaturase (3,4-didehydrolycopene-forming)] and EC 1.3.99.31 [phytoene desaturase (lycopene-forming)]).